CN107426881A

CN107426881A - Integrator, LED current ripple eliminate circuit and method, LED driver and LED device

Info

Publication number: CN107426881A
Application number: CN201710802581.4A
Authority: CN
Inventors: 江儒龙; 郜小茹
Original assignee: Shanghai Semiconducto Ltd By Share Ltd
Current assignee: Shanghai Semiconducto Ltd By Share Ltd
Priority date: 2017-09-07
Filing date: 2017-09-07
Publication date: 2017-12-01
Anticipated expiration: 2037-09-07
Also published as: CN107426881B

Abstract

The application, which provides a kind of integrator, LED current ripple elimination circuit and method, LED driver and LED device, the integrator, to be included：Voltage comparison module, for receiving input voltage and reference voltage, both are compared and corresponding logical signal is exported according to both comparative results；Counting module, the logical signal for being exported according to voltage comparison module are counted, and generate digital controlled signal；D/A converter module, the digital controlled signal for being exported to counting module carry out digital-to-analogue conversion, generate analog control signal.For using the combined correlation technique of difference amplifier and filter capacitor, circuit structure is simple and integrated level is higher, especially, it can remove from and configure big filter capacitor, the simplification of peripheral circuit is realized, reduces system cost, Problem of Failure caused by thoroughly eliminating peripheral filter electric capacity.

Description

Integrator, LED current ripple eliminate circuit and method, LED driver and LED device

Technical field

The application is related to field of LED drive technology, more particularly to a kind of integrator, LED current ripple eliminate circuit and Method, LED driver and LED device.

Background technology

LED (Light Emitting Diode, light emitting diode) is applied in a variety of electronic applications, such as：Building Illumination, vehicle head taillight, the backlight of the liquid crystal display including personal computer and HDTV and flash lamp etc.. Compared to the conventional lighting sources of such as incandescent lamp and fluorescent lamp etc, LED has the advantages of notable, including high efficiency, good direction Property, color stability, high reliability, long-life, small size and environmental safety etc..

LED is current-driven apparatus, and therefore, regulation is an important control technology by LED driving current.LED Driving power need to meet some requirements, such as：Reach can long-time fault-free use, can be according to the change of LED load And adjust, drive LED when be not in phenomenon of stroboscopic etc..Existing LED drive power species is various, but exist it is many not Foot, such as power factor are relatively low, and circuit is complicated, and also volume is big, cost height etc..

Such as：Gone in APFC BOOST driving powers and LED in the application of stroboscopic, it is necessary to which it is 1/10 to 1/4 to produce one The loop of low-frequency ripple frequency bandwidth, such loop usually require to add a big filter capacitor, in actual circuit so Filter capacitor typically all more than 1 μ F.Big filter capacitor can not realize in chip internal, in actual applications can only be outer Put, outside increased electric capacity, adding system cost, (such as electric capacity cost in itself and must being reserved on chip is drawn accordingly Pin) and failure risk.

The content of the invention

The deficiency of correlation technique in view of the above, the purpose of the application are to disclose a kind of integrator, LED current ripple Circuit, LED current ripple removing method, LED driver, LED drive chip and LED device are eliminated, for solving correlation technique Middle circuit structure is complicated, cost is higher and the problems such as larger failure risk be present.

In order to achieve the above objects and other related objects, the first aspect of the application is to disclose a kind of integrator, including： Voltage comparison module, for receiving input voltage and reference voltage, by the input voltage compared with the reference voltage And corresponding logical signal is exported according to both comparative results；Counting module, it is connected, is used for the voltage comparison module Counted according to the logical signal that the voltage comparison module exports, generate digital controlled signal；D/A converter module, with institute Counting module connection is stated, the digital controlled signal for being exported to the counting module carries out digital-to-analogue conversion, generation simulation control Signal.

In some embodiments of the application first aspect, the voltage comparison module according to both comparative result and Corresponding logical signal is exported, including：The first logical signal is exported when the input voltage is more than or equal to the reference voltage, And export the second logical signal when the input voltage is less than the reference voltage；The counting module is according to the electricity The logical signal of pressure comparison module output is counted, including：First is carried out when receiving first logical signal to count And carry out second when receiving second logical signal and count.

In some embodiments of the application first aspect, the counting module exports according to the voltage comparison module Logical signal counted, including：Carried out when receiving high level logic signal plus count and receiving low level Carry out subtracting counting during logical signal.

In some embodiments of the application first aspect, in a power frequency period, it is described plus count number and It is described subtract counting number it is identical, the incrementss and decrement of the digital controlled signal are equal.

In some embodiments of the application first aspect, the integrator also includes frequency generation module, and described Counting module connects, for exporting count frequency to the counting module.

In some embodiments of the application first aspect, the frequency generation module is voltage controlled oscillator, has two Input and an output end, wherein, an input is used to receive the input voltage, and another input is described for receiving Reference voltage, the output end are used to export count frequency；The count frequency is generated using below equation：F_CLK=K* | V_IN- V_REF|, wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is the coefficient of frequency modulation of voltage controlled oscillator.

The second aspect of the application is that disclosing a kind of LED current ripple eliminates circuit, including：Foregoing integration Device, the input voltage in the integrator are the negative terminal voltage of LED load and the difference of a sampled voltage；Signal adjusting module, It is connected with the D/A converter module in the integrator and the LED load, for what is exported according to the D/A converter module Analog control signal and the voltage or electric current for adjusting LED load so that the average current of the LED load keeps stable.

In some embodiments of the application second aspect, the signal adjusting module includes being located at the LED load Adjustment pipe between ground terminal, the control terminal of the adjustment pipe are connected with the output end of the D/A converter module.

In some embodiments of the application second aspect, the adjustment pipe is nmos pass transistor, the MOS transistor Grid be connected with the output end of the D/A converter module, the negative terminal of the drain electrode of the nmos pass transistor and LED load connects And the output end of the negative terminal voltage as LED load.

In some embodiments of the application second aspect, the signal adjusting module includes amplifier and adjustment is managed, The amplifier is connected with the D/A converter module, for the analog control signal that is exported according to the D/A converter module and One sampled voltage generates voltage regulation signal after carrying out signal enhanced processing, and the adjustment pipe is distinguished with the amplifier and LED load Electrical connection, for the electric current of the LED load to be adjusted and stablized according to the voltage regulation signal.

In some embodiments of the application second aspect, the amplifier is operational amplifier, and the adjustment pipe is Nmos pass transistor, wherein, the grid of the nmos pass transistor is connected with the output end of the operational amplifier, the NMOS crystal The drain electrode of pipe and the negative terminal of LED load connect and are used as the output end of the negative terminal voltage of LED load, the source of the nmos pass transistor Pole connects ground terminal by a sampling resistor and is used as the output end of the sampled voltage, the first input end of the operational amplifier It is connected with the output end of the D/A converter module, the second input of the operational amplifier and the source of the nmos pass transistor Pole connects.

The third aspect of the application is that disclosing a kind of LED ripples eliminates chip, including：Foregoing LED ripples disappear Except circuit or foregoing integrator.

The fourth aspect of the application is to disclose a kind of LED driver, including：Foregoing integrator, the integration Input voltage in device is LED negative terminal voltages；D/A converter module in signal adjusting module, with the integrator and described LED load is connected, and the voltage of the LED load is adjusted for the analog control signal exported according to the D/A converter module Or electric current so that the average current of the LED load keeps stable.

In some embodiments of the application fourth aspect, the signal adjusting module include pulse-width modulator and Switching tube, wherein, the pulse-width modulator is connected with the D/A converter module, for according to the D/A converter module The analog control signal of output and carry out the pulse width modulation of signal to generate switch controlled signal, the switching tube and institute Pulse-width modulator connection is stated, is led for the switch controlled signal exported according to the pulse-width modulator Logical/shut-off operation.

In some embodiments of the application fourth aspect, the pulse-width modulator is a comparator, the ratio First input end compared with device is connected with the D/A converter module, and the second input connects a sawtooth waveforms or triangular signal, For the analog control signal that is exported according to the D/A converter module compared with the sawtooth waveforms or triangular signal Control signal is generated, for adjusting the ON time of switching tube.

In some embodiments of the application fourth aspect, the input voltage in the integrator is and LED load electricity The voltage of one sampling resistor of connection, the other end ground connection of the sampling resistor.

The 5th aspect of the application is to disclose a kind of LED drive chip, it is characterised in that including：Foregoing product Divide device or foregoing LED driver.

It is to disclose a kind of LED device in terms of the 6th of the application, including：LED load；Rectifier bridge, the rectifier bridge Input is electrically connected to an AC power, for being direct current by AC rectification；First electric capacity, the both ends of first electric capacity Two rectification branch roads in parallel in the rectifier bridge are respectively electrically connected to, for being filtered to direct current；Energy storage inductor, afterflow Diode and the second electric capacity, after second electric capacity is in parallel with LED load with the fly-wheel diode and the energy storage inductor Series connection, the other end of the energy storage inductor are coupled to a rectification branch road of the rectifier bridge；Driven using foregoing LED Device, it is arranged between the LED load and the energy storage inductor, for adjusting and stablizing the electric current of the LED load.

It is to disclose a kind of LED device in terms of the 7th of the application, including：LED load；Ripple electric capacity is removed, is parallel to institute State LED load；LED constant current drive device, with the LED load and it is described go ripple capacitance connection, it is one constant for exporting LED drive current；Foregoing LED current ripple eliminates circuit, located at the LED load and LED constant current driving dress Between putting.

The eighth aspect of the application is to disclose a kind of LED current ripple removing method, comprised the following steps：Obtain with The related input voltage of LED load, by the input voltage compared with a reference voltage and according to both comparative results And export corresponding logical signal；Counted based on the logical signal to generate digital controlled signal；To the numeral control Signal processed carries out digital-to-analogue conversion to generate the gentle analog control signal that rises and falls；According to the analog control signal, adjustment LED is born The voltage or electric current of load are stable to cause the holding of the average current of the LED load.

In some embodiments of the application eighth aspect, by the input voltage compared with a reference voltage simultaneously The step of exporting corresponding logical signal according to both comparative results includes：The input voltage and a reference voltage are entered Row compares, and the first logical signal is exported when the input voltage is more than or equal to the reference voltage, and, in the input electricity Pressure exports the second logical signal when being less than the reference voltage；The step of being counted based on the logical signal includes being based on institute The first logical signal is stated to carry out the first counting and carry out the second counting based on second logical signal.

In some embodiments of the application eighth aspect, the step of being counted based on the logical signal, includes base Carry out plus count in high level logic signal and carry out subtracting counting based on low-level logic signal.

In some embodiments of the application eighth aspect, in a power frequency period, it is described plus count number and It is described subtract counting number it is identical, the incrementss and decrement of the digital controlled signal are equal.

In some embodiments of the application eighth aspect, when being counted, the count frequency that is based on use with Lower formula generation：F_CLK=K* | V_IN-V_REF|, wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is The coefficient of frequency modulation of voltage controlled oscillator.

In some embodiments of the application eighth aspect, the step of obtaining related to LED load input voltage, wraps Include：The negative terminal voltage of LED load is detected, using the difference of the negative terminal voltage and a sampled voltage as input voltage；Or inspection The negative terminal voltage of LED load is surveyed, using the negative terminal voltage as input voltage.

Integrator disclosed in the present application, LED current ripple eliminate circuit, LED current ripple removing method, LED driver, LED drive chip and LED device, phase is exported by input voltage compared with reference voltage and according to both comparative results The logical signal answered, counted according to logical signal and count frequency to form corresponding digital controlled signal, then by numeral Control signal carries out digital-to-analogue conversion to form analog control signal, compared to using difference amplifier (trsanscondutance amplifier) and filtering For the combined correlation technique of electric capacity, circuit structure is simple and integrated level is higher, especially, can remove from and configure big filtered electrical Hold, realize the simplification of peripheral circuit, reduce system cost, Problem of Failure caused by thoroughly eliminating peripheral filter electric capacity.

Brief description of the drawings

Fig. 1 is shown as using the electrical block diagram using big filter capacitor in correlation technique.

Fig. 2 is shown as the circuit theory diagrams of the application integrator in one embodiment.

Fig. 3 is shown as the circuit theory diagrams of the application integrator in another embodiment.

Fig. 4 is shown as the electrical block diagram of integrator in one embodiment in Fig. 3.

Fig. 5 is shown as the timing diagram of each signal in Fig. 4.

Fig. 6 is shown as the schematic diagram of the application LED device in one embodiment.

Fig. 7 is shown as the schematic diagram of the application LED device in another embodiment.

Fig. 8 is shown as the structure chart of LED device in one embodiment shown in Fig. 6.

Fig. 9 is shown as the electrical block diagram of LED device in one embodiment in Fig. 8.

Figure 10 is shown as the schematic flow sheet of the application LED current ripple removing method in one embodiment.

Figure 11 is shown as the structure chart of the application LED device in another embodiment.

Figure 12 is shown as the electrical block diagram of LED device in one embodiment in Figure 11.

Embodiment

Presently filed embodiment is illustrated by particular specific embodiment below, those skilled in the art can be by this explanation Content disclosed by book understands other advantages and effect of the application easily.

In described below, refer to the attached drawing, accompanying drawing describes some embodiments of the application.It should be appreciated that also it can be used Other embodiment, and can be carried out in the case of without departing substantially from spirit and scope mechanical composition, structure, electrically with And operational change.Following detailed description should not be considered limiting, and the scope of embodiments herein Only limited by the claims for the patent announced.Term used herein is merely to describe specific embodiment, and be not It is intended to limit the application.The term of space correlation, for example, " on ", " under ", "left", "right", " following ", " lower section ", " bottom ", " top ", " top " etc., it can use in the text in order to illustrate an element shown in figure or feature and another element or spy The relation of sign.

Although the grade of term first, second is used for describing various elements herein in some instances, these elements It should not be limited by these terms.These terms are only used for making a distinction an element with another element.For example, first is pre- If threshold value can be referred to as the second predetermined threshold value, and similarly, the second predetermined threshold value can be referred to as the first predetermined threshold value, and The scope of various described embodiments is not departed from.First predetermined threshold value and predetermined threshold value are to describe a threshold value, still Unless context otherwise explicitly points out, otherwise they are not same predetermined threshold values.Similar situation also includes first Volume and the second volume.

Furthermore as used in herein, singulative " one ", "one" and "the" are intended to also include plural shape Formula, unless there is opposite instruction in context.It will be further understood that term "comprising", " comprising " show described spy be present Sign, step, operation, element, component, project, species, and/or group, but it is not excluded for other one or more features, step, behaviour Presence, appearance or the addition of work, element, component, project, species, and/or group.Term "or" used herein and "and/or" quilt It is construed to inclusive, or means any one or any combinations.Therefore, " A, B or C " or " A, B and/or C " mean " with Descend any one：A；B；C；A and B；A and C；B and C；A, B and C ".Only when element, function, step or the combination of operation are in some sides When inherently mutually exclusive under formula, the exception of this definition just occurs.

Inventors herein have recognized that, it is necessary to which it is 1/10 to 1/4 low frequency to produce one in the LED actuation techniques of correlation The loop of ripple frequency bandwidth, the method that this low bandwidth is realized in correlation technique is to add a big filter capacitor.It please join Fig. 1 is read, is shown as using the electrical block diagram of big filter capacitor in correlation technique.In the related art, the circuit bag Include difference amplifier EA and filter capacitor C.Difference amplifier EA is substantially a trsanscondutance amplifier, and two input connects respectively Receive input voltage V_INWith reference voltage V_REF, can be by input voltage V_INWith reference voltage V_REFThe input difference voltage formed turns It is changed to output current, i.e. the electric current of output is proportional to input voltage V_INWith reference voltage V_REFVoltage difference.Difference amplifier It is electrically operated that the electric current of EA outputs can carry out charge and discharge to filter capacitor C.Specifically, as input voltage V_INMore than or equal to reference voltage V_REFWhen, the electric current of difference amplifier EA outputs discharges filter capacitor C, the COMP voltages of difference amplifier EA output ends Slowly reduce；Input voltage V_INLess than reference voltage V_REFWhen, the electric current of difference amplifier EA outputs fills to filter capacitor C Electricity, COMP voltages slowly increase.Because the big compensating electric capacity of selection, loop bandwidth is very slow, and COMP changes are slow, a public frequency week It is held essentially constant in phase.But, such a big filter capacitor (filter capacitor typically all obtains more than 1 μ F) can not be integrated in In related control chip, and external mode can only be taken to be connected to related control chip, in this way, adding whole circuit The complexity of structure, and cause the increase of whole application cost (such as the cost of filter capacitor and phase must be reserved on chip The pin answered) and crash rate increase.In view of this, present inventor is directed to correlation technique and proposing one kind can avoid Using the integrator of the external mode of bulky capacitor, and it is configured with LED current ripple elimination circuit, the LED current ripple of the integrator Removing method, LED ripples eliminate chip, LED driver and LED drive chip and LED device.

The application provides a kind of integrator on the one hand, and the integrator includes voltage comparison module, counting module and number Mould modular converter.

Voltage comparison module can be used for receiving input voltage and reference voltage, by the input voltage received and reference voltage It is compared and corresponding logical signal is exported according to both comparative results.In the present embodiment, it is referring to Fig. 2, aobvious It is shown as the circuit theory diagrams of the application integrator in one embodiment.As shown in Fig. 2 voltage comparison module 11 is defeated for receiving Enter voltage V_INWith reference voltage V_REF, by input voltage V_INWith reference voltage V_REFIt is compared and the comparative result according to both And export corresponding logical signal.In actual applications, by input voltage V_INWith reference voltage V_REFIt is compared and according to input Voltage V_INWith reference voltage V_REFComparative result and export corresponding logical signal can for example including：As input voltage V_INIt is more than Equal to reference voltage V_REFWhen, voltage comparison module 11 exports the first logical signal；And work as input voltage V_INLess than reference voltage V_REFWhen, voltage comparison module 11 exports the second logical signal.In one embodiment, voltage comparison module 11 is according to both ratios Relatively result and exporting corresponding logical signal may include：In input voltage V_INMore than or equal to reference voltage V_REFWhen export high level Logical signal, and, in input voltage V_INLess than reference voltage V_REFWhen export low-level logic signal.In another embodiment, Voltage comparison module 11, which exports corresponding logical signal according to both comparative results, may include：In input voltage V_INMore than etc. In reference voltage V_REFWhen export low-level logic signal, and, in input voltage V_INLess than reference voltage V_REFWhen the high electricity of output Flat logical signal.

Counting module is connected with voltage comparison module, carry out by the logical signal exported according to voltage comparison module based on Number, generate digital controlled signal.In the present embodiment, as shown in Fig. 2 counting module 12 is connected with voltage comparison module 11, For receiving the logical signal exported from voltage comparison module 11 and being counted according to the logical signal, so as to generate number Word control signal.With it is foregoing accordingly, in actual applications, the logic that counting module 12 exports according to voltage comparison module 11 Signal carry out counting can for example including：The first meter is carried out when receiving the first logical signal of the output of voltage comparison module 11 Number, the second counting is carried out when receiving the second logical signal of the output of voltage comparison module 11, passes through the first counting and second Count, so as to generate the digital controlled signal with certain dutycycle.In one embodiment, counting module 12 according to voltage ratio compared with The logical signal that module 11 exports, which carries out counting, may include：Carry out plus count when receiving high level logic signal, and, Carry out subtracting counting when receiving low-level logic signal.Certainly, it is not limited thereto, equally, in another embodiment, count module The logical signal that block 12 exports according to voltage comparison module 11 carries out counting and may also comprise：When receiving low-level logic signal Carry out plus count, and, carry out subtracting counting when receiving high level logic signal.

D/A converter module is connected with counting module, and the digital controlled signal for being exported to counting module carries out digital-to-analogue and turned Change, generate analog control signal.In the present embodiment, as shown in Fig. 2 D/A converter module 14 is connected with counting module 12, Digital controlled signal for being exported to counting module 12 carries out digital-to-analogue conversion, generates analog control signal.It can be said that by number The analog control signal that mould modular converter 14 exports is for one relative to reference voltage V_REFRise and fall gradual low frequency signal, in this way, can To say that the analog control signal formed is that change is gentle in power frequency period.

In another embodiment, the integrator that the application provides is except voltage comparison module, counting module and digital-to-analogue Frequency generation module is may also include outside modular converter.The frequency generation module is connected with the counting module, for institute State counting module output count frequency.Referring to Fig. 3, it is shown as the circuit theory of the application integrator in another embodiment Figure.As shown in figure 3, the application integrator includes：Voltage comparison module 11, counting module 12, frequency generation module 13 and number Mould modular converter 14.

In the present embodiment, voltage comparison module 11 is used to receive input voltage V_INWith reference voltage V_REF, by input electricity Press V_INWith reference voltage V_REFIt is compared and corresponding logical signal is exported according to both comparative results.In an embodiment In, voltage comparison module 11 is by input voltage V_INWith reference voltage V_REFIt is compared and according to input voltage V_INWith reference voltage V_REFComparative result and exporting corresponding logical signal may include：By input voltage V_INWith reference voltage V_REFIt is compared, when Input voltage V_INMore than or equal to reference voltage V_REFWhen export high level logic signal, and, as input voltage V_INLess than reference Voltage V_REFWhen export low-level logic signal.Certainly, in another embodiment, voltage comparison module 11 is according to both comparisons As a result corresponding logical signal is exported to may also comprise：In input voltage V_INMore than or equal to reference voltage V_REFWhen export low level Logical signal, and, in input voltage V_INLess than reference voltage V_REFWhen export high level logic signal.

Frequency generation module 13 is connected with counting module 12, for exporting count frequency to counting module 12, for counting Module 12 can carry out corresponding counts according to count frequency.In one embodiment, the count frequency of the generation of frequency generation module 13 is With input voltage V_INWith reference voltage V_REFIt is related, for example, the count frequency that frequency generation module 13 generates is and input voltage V_INWith reference voltage V_REFThe directly proportional relation of pressure difference between the two, i.e.,：Input voltage V_INWith reference voltage V_REFBetween the two Pressure difference it is bigger, then the count frequency generated is higher；Input voltage V_INWith reference voltage V_REFPressure difference between the two is smaller, The count frequency then generated is with regard to relatively low.

Counting module 12 is connected with voltage comparison module 11 and frequency generation module 13, for receiving from voltage ratio compared with mould The logical signal of the output of block 11 and the count frequency of frequency generation module 13 are simultaneously counted according to this, so as to generate digital control letter Number.In one embodiment, counting module 12 carries out counting according to logical signal and count frequency may include：Receiving voltage ratio When the logical signal exported compared with module 11 is high level logic signal, then carries out plus count；Receiving voltage comparison module 11 When the logical signal of output is low-level logic signal, then carry out subtracting counting.And when being counted, Count .- Duration is then It is in the relation of inverse ratio with count frequency, i.e.,：Count frequency is higher, then Count .- Duration is shorter；Count frequency is lower, then counts Duration is longer.So, with reference to foregoing middle input voltage V_INWith reference voltage V_REFTwo parameters, according to logical signal and meter Counting the trend that frequency is counted substantially is：If input voltage V_INMore than or equal to reference voltage V_REF, then carry out plus count, and if Input voltage V_INWith reference voltage V_REFBetween pressure difference it is bigger (or smaller), then carry out plus count count frequency it is higher (or more It is low)；If input voltage V_INLess than reference voltage V_REF, then carry out subtracting counting, and if input voltage V_INWith reference voltage V_REFBetween Pressure difference it is bigger (or smaller), then the count frequency for carrying out subtracting counting is higher (or lower).In this way, by counting module 12 through counting The digital controlled signal generated afterwards can not only integrally adapt to input voltage V_INWith reference voltage V_REFBetween comparative result and Slow degree is and input voltage V suddenly for it_INWith reference voltage V_REFBetween pressure difference it is related.

D/A converter module 14 is connected with counting module 12, and the digital controlled signal for being exported to counting module 12 is carried out Digital-to-analogue conversion, generate analog control signal.It can be said that the analog control signal exported by D/A converter module 14 is relative for one In reference voltage V_REFRise and fall gradual low frequency signal, so, it may be said that the analog control signal of formation is to become in power frequency period Change gently.

The integrator that the application provides, is a kind of circuit for being able to carry out integral operation, its analog control signal exported It is the integration of input signal, using voltage comparison module, frequency generation module, counting module and D/A converter module, can makes Analog control signal is obtained as one relative to reference voltage V_REFRise and fall gradual low frequency signal, filter out high frequency in input signal into Point.

Referring to Fig. 4, the electrical block diagram of the integrator being shown as in Fig. 3 in one embodiment.

In the fig. 4 embodiment, voltage comparison module 11 can be for example with voltage comparator, the positive of voltage comparator 11 Input is used to receive input voltage V_IN, the inverting input of voltage comparator 11 is for receiving a default reference voltage V_REF。 Specifically, the input voltage V that voltage comparator 11 will receive_INWith reference voltage V_REFBe compared, and according to comparative result and Export the first logical signal or the second logical signal.In detail, voltage comparator 11 exports the first logic according to comparative result Signal or the second logical signal specifically include：As input voltage V_INIt is greater than being equal to reference voltage V_REFWhen, then output is high level The first logical signal (first logical signal may be, for example, " 1 " logical signal, and the first logical signal of the high level can be referred to as For high level logic signal)；As input voltage V_INIt is less than reference voltage V_REFWhen, then output is believed for low level second logic Number (second logical signal may be, for example, " 0 " logical signal, and low level second logical signal may be simply referred to as low-level logic Signal).Certainly, above-mentioned voltage comparator 11 is to input voltage V_INWith reference voltage V_REFManner of comparison be merely illustrative, And it is not used to limit the rights protection scope of the application, for example, in other embodiments, the inverting input of voltage comparator 11 For receiving input voltage V_IN, the normal phase input end of voltage comparator 11 is for receiving a default reference voltage V_REF, so, As input voltage V_INIt is greater than being equal to reference voltage V_REFWhen, then for low level first logical signal, (first logic is believed for output Number may be, for example, " 0 " logical signal, low level first logical signal may be simply referred to as low-level logic signal)；When input electricity Press V_INIt is less than reference voltage V_REFWhen, then for the second logical signal of high level, (second logical signal may be, for example, for output " 1 " logical signal, the second logical signal of the high level may be simply referred to as high level logic signal).Substantially, using voltage ratio compared with Device 11 is by input voltage V_INWith reference voltage V_REFIt is compared and corresponding logical signal is exported according to both comparative results It is exactly the important devices that signal carries out analog-to-digital conversion in fact.

In the fig. 4 embodiment, frequency generation module 13 can be for example with voltage controlled oscillator (Voltage-Controlled Oscillator, abbreviation VCO), the voltage controlled oscillator 13 has two inputs and an output end, wherein, an input is used for Receive input voltage V_IN, another input is for receiving reference voltage V_REF, output end is then for exporting count frequency.Due to That two inputs of voltage controlled oscillator 13 receive is input voltage V_INWith reference voltage V_REF, therefore, the count frequency of output For：F_CLK=K* | V_IN-V_REF|, wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is VCO The coefficient of frequency modulation of device.As can be seen here, the output frequency of voltage controlled oscillator 13 is and input voltage V_INWith reference voltage V_REFBetween Pressure difference is directly proportional, i.e. if input voltage V_INWith reference voltage V_REFBetween pressure difference it is bigger, then output frequency is higher；If input electricity Press V_INWith reference voltage V_REFBetween pressure difference it is smaller, then output frequency is lower.

In the fig. 4 embodiment, counting module 12 can be for example with forward-backward counter, the forward-backward counter 12 and voltage ratio Connected compared with device 11 and voltage controlled oscillator 13, for receive voltage comparator 11 output high level logic signal when according to pressure The count frequency that controlled oscillator 13 exports is carried out plus counted and receiving the low-level logic letter of the output of voltage comparator 11 Number when according to voltage controlled oscillator 13 export count frequency carry out subtracting counting.Certainly, above-mentioned forward-backward counter 12 is patrolled high level Volume signal is carried out plus counted and low-level logic signal is carried out subtracting counting and is merely illustrative, and is not used to limit this Shen Rights protection scope please, for example, in other embodiments, forward-backward counter 12 can also use to enter high level logic signal Row subtracts the counting mode for counting and carrying out plus counting to low-level logic signal.Because forward-backward counter 12 carries out plus-minus counting It is that (logical signal is and input voltage V with logical signal_INWith reference voltage V_REFComparative result it is related) and count frequency (meter Counting frequency is and input voltage V_INWith reference voltage V_REFBetween pressure difference it is related) it is related, thus, by counting module 12 through counting The digital controlled signal generated afterwards can not only integrally adapt to input voltage V_INWith reference voltage V_REFBetween comparative result and Slow degree is and input voltage V suddenly for it_INWith reference voltage V_REFBetween pressure difference it is related.From the foregoing, it will be observed that by setting suitable ginseng Examine voltage V_REF, may be such that output signal for one relative to reference voltage V_REFRise and fall gradual low frequency signal, has filtered out former input Signal V_INIn it is possible that radio-frequency component.

In the fig. 4 embodiment, D/A converter module 14 can use conventional digital analog converter (Digital to Analog Converter, abbreviation DAC), the digital analog converter 14 is connected with forward-backward counter 12, for by forward-backward counter 12 Carry out plus count and subtract and count exported digital controlled signal progress digital-to-analogue conversion, generation analog control signal V_COMP。

With additional reference to Fig. 5, the timing diagram of each signal in Fig. 4 is shown as.As shown in figure 5, voltage comparator 11 will receive Input voltage V_INWith default reference voltage V_REFIt is compared, as input voltage V_INMore than or equal to reference voltage V_REFWhen, just High level logic signal (for example, high level logic signal is output " 1 ") is exported, as input voltage V_INLess than reference voltage V_REF When, just export low-level logic signal (for example, low-level logic signal is output " 0 ").Forward-backward counter 12 is receiving height Just carry out plus count during level logic signal, and add the count frequency counted to be and input voltage V_INWith reference voltage V_REFBetween Pressure difference it is directly proportional, i.e. if input voltage V_INWith reference voltage V_REFBigger (that is, the input voltage V of pressure difference_INSubtract with reference to electricity Press V_REFThe difference of gained is bigger), then plus count frequency is higher；If input voltage V_INWith reference voltage V_REFPressure difference it is smaller (i.e., Input voltage V_INSubtract reference voltage V_REFThe difference of gained is smaller), then plus count frequency is lower.Forward-backward counter 12 is receiving Just carry out subtracting counting during low-level logic signal, and the count frequency for subtracting counting is and input voltage V_INWith reference voltage V_REFIt Between pressure difference it is directly proportional, i.e. if input voltage V_INWith reference voltage V_REFBigger (that is, the reference voltage V of pressure difference_REFSubtract input Voltage V_INThe difference of gained is bigger), then it is higher to subtract count frequency；If input voltage V_INWith reference voltage V_REFPressure difference it is smaller (that is, reference voltage V_REFSubtract input voltage V_INThe difference of gained is smaller), then it is lower to subtract count frequency.This characteristic shows Fig. 5 In it can be seen that, the digital controlled signal that exports after forward-backward counter 12 carries out plus-minus counting, if input voltage V_INWith ginseng Examine voltage V_REFBetween pressure difference it is bigger, count frequency is higher, and Count .- Duration is shorter, the ripple of the digital controlled signal of formation Shape is shorter on the time shaft of transverse direction, and waveform integrally just seems more precipitous；If input voltage V_INWith reference voltage V_REFPressure difference Smaller, count frequency is lower, and Count .- Duration is longer, the waveform of the digital controlled signal of formation on the time shaft of transverse direction just Longer, waveform integrally just seems gentle.Counted for single, the waveform of the digital controlled signal of formation on a timeline when Between be inversely proportional with count frequency.When in stable state, in a power frequency period, add the number of counting and subtract counting Number it is identical, the incrementss and decrement of the digital controlled signal of formation are equal.Digital-to-analogue is carried out by digital analog converter 14 to turn Analog control signal V is exported after changing_COMP, it can be seen that as input voltage V_INMore than or equal to reference voltage V_REFWhen obtained simulation Control signal V_COMPIt is boost signal, as input voltage V_INLess than reference voltage V_REFWhen obtained analog control signal V_COMPThen It is buck signal.As shown in Figure 5, in a power frequency period, the number for adding counting is identical with the number for subtracting counting, in this way, logical Cross the control signal V that digital analog converter 14 exports after digital-to-analogue conversion_COMPIncrementss and decrement in a power frequency period It is and equal.In general, analog control signal V_COMPChange is gentle, thus, it is believed that analog control signal V_COMPIn power frequency It is stable in cycle.

From the foregoing, it will be observed that the integrator that the application provides, employs voltage comparison module, frequency generation module, counting module And D/A converter module, using voltage comparison module by input voltage compared with reference voltage and according to both comparison knots Fruit and export corresponding logical signal, the logical signal and frequency generation module exported by counting module according to voltage comparison module The count frequency of output is counted to form corresponding digital controlled signal, then is exported counting module by D/A converter module Digital controlled signal carry out digital-to-analogue conversion to form analog control signal, compared to using difference amplifier (trsanscondutance amplifier) With filter capacitor for combined correlation technique, circuit structure is simple and integrated level is higher, especially, can remove from and configure big Filter capacitor, the simplification of peripheral circuit is realized, reduces system cost, failed and ask caused by thoroughly eliminating peripheral filter electric capacity Topic.

Referring to Fig. 6, it is shown as the schematic diagram of the application LED device in one embodiment.As shown in fig. 6, the application LED device includes：LED load 10, ripple electric capacity C0, LED constant current drive device 20 and LED current ripple is gone to eliminate chip 30。

LED load 10 can be made up of a LED or multiple LEDs, it is possible to provide the application scenarios such as illumination and instruction flash of light In.

Go ripple electric capacity C0 to be parallel to LED load 10, specifically, go ripple electric capacity C0 first end and LED load 10 Anode connects, and goes to ripple electric capacity C0 the second end to be then connected with ground terminal.

LED constant current drive device 20 is used to provide input current.LED constant current drive device 20 exports one and contains power frequency line The current signal of ripple, the current signal containing ripple will produce the voltage containing working frequency ripple wave on ripple electric capacity C0 is removed Signal.In the present embodiment, LED constant current drive device 20 may be, for example, APFC LED driver.

" power factor " in PFC (Power Factor Correction, abbreviation PFC), has been referred to Imitate the relation between power and total power consumption (apparent energy), that is, the ratio of effective power divided by total power consumption (apparent energy) Value.Substantially power factor (PF) can weigh the degree that electric power is used effectively, and when power factor (PF) value is bigger, represent the utilization of its electric power Rate is higher.Current PFC technologies mainly include passive PFC (also known as passive PFC) and active PFC (also known as active PFC, Active Power Factor Correction, APFC).The volume of passive PFC technologies is larger, it is necessary to increase extra element Preferably to change current waveform, about 0.8 or higher power factor can be reached, wherein.In the relatively low work(less than 5W to 40W In rate application, the reverse exciting topological structure of almost standard selection is only needed using passive element and slightly circuit change, you can Realize the power factor higher than 0.7.Active PFC technologies increase to circuit typically as a special Power convert section Change input current waveform.The LED power of low power factor is because input is terminated with bulky capacitor filtering, therefore the ripple electricity exported Press very little, also even close to not having, the LED of no stroboscopic will not make one to come over dizzy very little for the stroboscopic of LED, while can be with It is uncomfortable to reduce the eyes that bring of working long hours, but the bulky capacitor of input is while stroboscopic is reduced, can also make power because Number reduces, and the power supply of low power factor can not only accelerate the loss of circuit, can also increase the burden of supply transformer, make whole electricity The conveying capacity and power grid quality of net weaken significantly.The active the commonly provided boostings of PFC, exchange 100Vac to 277Vac wide input In the range of, PFC output voltage ranges reach direct current 450Vdc to 277Vdc.In active PFC, it is desirable to provide special DC-DC turns Parallel operation provides electric current current stabilization, i.e.,：Dc-dc is accessed between rectifier and load, applied current feedback technique, is made defeated Enter to hold current waveform tracking exchange input sinusoidal voltage waveform, its nearly sine wave can be made, so that input electric current is total humorous Wave distortion THD is less than 5%, and so, power factor can be improved to 0.9 even more high.Conventional APFC It is divided into continuous current mode control type and the class of discontinuous current mode control type two, wherein, continuous current mode control type is main There is point of booster type (Boost), voltage-dropping type (Buck), buck-boost type (Buck-Boost).Electricity is controlled for booster type (Boost) Road, in one embodiment, can for example including：Rectifier bridge, filter capacitor, energy storage inductor and fly-wheel diode etc., wherein, institute The input for stating rectifier bridge is electrically connected to an AC power, for being direct current by AC rectification；The two of the filter capacitor End is respectively electrically connected to two rectification branch roads in parallel in the rectifier bridge, for being filtered to direct current, to suppress radio frequency Disturb (Radio Frequency Interference, abbreviation RFI) and electromagnetic interference (Electromagnetic Interference, abbreviation EMI) noise, and can prevent power network from being impacted to the high frequency transient of main circuit；The energy storage inductor connection Acted on a rectification branch road of the rectifier bridge, primarily serving energy storage, while the ripple output of electric current can be reduced.It is discontinuous Current-mode controlled point for having normal shock type (Forward), flyback (Fly-back).The LED power of High Power Factor due to Power factor is high, the cost of circuit line footpath can also be reduced while mitigating power network burden, but its output current contains (such as mains frequency is 50Hz to 100HZ/120HZ working frequency ripple wave composition, then the LED power output current of High Power Factor contains There is a 100Hz ripple, the also ripple containing 100Hz of the electric current in LED, the stroboscopic for making light output contain 100Hz), with height Although its imperceptible stroboscopic of LED naked eyes of power factor, much time using can cause the visual fatigue of people, influence The health of eyes.

LED current ripple eliminates chip 30, between LED driver 20 and LED load 10.In the present embodiment, LED current ripple eliminates chip 30 and comprised at least：Power end HV, voltage adjustment end Drain, current detecting end CS and ground terminal Connection end GND.Power end HV is connected with the anode of LED load 10, for obtaining supply voltage, with to applied to LED current line Ripple eliminates each circuit or component in chip 30 and provides power supply.Further, power end HV more can start resistance R0 by one And it is connected with the anode of LED load 10.Voltage adjustment end Drain is connected with the negative terminal of LED load 10, for detecting and obtaining The negative terminal voltage of LED load 10.Current detecting end CS can pass through a sampling resistor R_CSAnd it is connected with ground terminal and exports sampled voltage. Ground terminal connection end GND is connected with ground terminal.LED current ripple eliminates chip 30 by detecting the negative terminal voltage of LED load 10, according to The comparative result of negative terminal voltage and default reference voltage and generate stable analog control signal, to control LED load to obtain The driving current that must stablize, so as to eliminate the current ripples of LED load and cause the average current of LED load to keep stable.

It will be appreciated from fig. 6 that in the application LED device, LED current ripple eliminates chip 30 and is configured as detecting LED load 10 negative terminal voltage and according to the variable condition of the negative terminal voltage and dynamic generation analog control signal, for controlling LED to bear The driving current of load so that LED load obtains stable driving current, so as to eliminate the current ripples of LED load.Compared to normal The correlation technique of rule, LED current ripple, which eliminates chip 30, can remove the big filter capacitor of configuration from, realize the letter of peripheral circuit Change, reduce system cost, Problem of Failure caused by thoroughly eliminating peripheral filter electric capacity.

It is noted that Fig. 6 is only an exemplary illustration, but is not intended to limit the protection domain of the application, for example, Fig. 7 separately is see, is shown as the schematic diagram of the application LED device in another embodiment.It is as shown in fig. 7, another at this In individual embodiment, the LED current ripple in LED device eliminates chip 30, comprises at least：Power end HV, voltage adjustment end Drain, current detecting end CS and with ground terminal connection end GND.Power end HV is connected with the negative terminal of LED load 10, for obtaining Supply voltage is obtained, to eliminate each circuit or component offer power supply in chip 30 to applied to LED current ripple.Voltage is adjusted Whole end Drain is connected with the negative terminal of LED load 10, for detecting and obtaining the negative terminal voltage of LED load 10 as input voltage. Current detecting end CS can pass through a sampling resistor R_CSAnd it is connected with ground terminal and exports sampled voltage.Ground terminal connection end GND and ground terminal Connection.In the LED device shown in Fig. 7, power end HV is connected with the negative terminal of LED load 10, voltage adjustment end Drain with The negative terminal connection of LED load 10, therefore, chip 30 is eliminated for LED current ripple, power end HV pin can be adjusted with voltage Whole end Drain pin realizes multiplexing, can be achieved to simplify circuit and chip structure, reduces design and manufacturing cost.

Please continue to refer to Fig. 8, the structure chart of LED device in one embodiment in Fig. 6 is shown as.As shown in figure 8, at this In embodiment, the application LED device includes：LED load 10, remove ripple electric capacity C0, LED constant current drive device 20 and LED Current ripples eliminate circuit, wherein, LED ripples eliminate circuit and are integrated with LED ripples elimination chip.

LED driver 20 is used to provide input current.LED driver 20 exports an electric current letter containing working frequency ripple wave Number, the current signal containing ripple will produce a voltage signal containing working frequency ripple wave on ripple electric capacity C0 is removed.At this In embodiment, LED driver may be, for example, APFC LED driver.

The LED current ripple, which eliminates built-in chip type, has power supply circuit and LED current ripple to eliminate circuit.

The power supply circuit is connected with LED load 10 and LED driver 20, is disappeared for generating applied to LED current ripple Except the power supply of each circuit or component in chip 30.Further, in one embodiment, the power supply circuit can also be at least Including undervoltage lockout circuit (Under Voltage Lock-Out, abbreviation UVLO) and biasing and generating circuit from reference voltage etc..

UVLO is exactly undervoltage lockout circuit, for ensuring once supply voltage eliminates opening for chip less than LED current ripple When opening threshold voltage, system is closed in a controlled manner, so as to which unstable vibration will not be produced or into pressure conditions, so as to Ensure that LED current ripple eliminates chip and is not to be damaged in supply voltage deficiency.For more stable work, some DC/ DC converters have UVLO functions.After electric power starting, UVLO functions make internal circuit be in holding state, until DC/DC is changed Input voltage (the V of device_IN) reach UVLO voltages, reduce current drain with this and avoid maloperation.

Biasing and generating circuit from reference voltage are connected with the undervoltage lockout circuit, for producing corresponding bias voltage V_biasAnd/or reference voltage V_REF.In a kind of specific example, biasing and reference voltage can produce bias voltage V_bias.Another In kind specific example, biasing and reference voltage generating reference voltages V_REF.In another example, biasing and reference voltage can Produce bias voltage V_biasWith reference voltage V_REF。

The LED current ripple, which eliminates circuit, may include foregoing integrator, and the integrator may include：Voltage ratio is compared with mould Block 11, counting module 12, frequency generation module 13 and D/A converter module 14.In addition, the LED current ripple eliminates electricity Road may also include signal adjusting module, and the signal adjusting module is connected with the integrator and LED load 10, for according to institute State the analog control signal of integrator output and adjust the voltage or electric current of LED load 10 so that the average current of LED load 10 Keep stable and the current ripples of LED load can be eliminated.

Voltage comparison module can be used for receiving input voltage and reference voltage, by the input voltage received and reference voltage It is compared and corresponding logical signal is exported according to both comparative results.As shown in figure 8, in the present embodiment, electricity Pressure comparison module 11 is used to receive input voltage V_INWith reference voltage V_REF, by input voltage V_INWith reference voltage V_REFCompared Compared with and according to both comparative result and export corresponding logical signal.It should be noted that in the present embodiment, voltage ratio compared with The input voltage that module 11 is received may be, for example, the negative terminal voltage of LED load 10 and the difference of a sampled voltage.Actually should In, by input voltage V_INWith reference voltage V_REFIt is compared and according to input voltage V_INWith reference voltage V_REFComparison knot Fruit and export corresponding logical signal can for example including：As input voltage V_INMore than or equal to reference voltage V_REFWhen, voltage ratio is compared with mould Block 11 exports the first logical signal；And work as input voltage V_INLess than reference voltage V_REFWhen, the output of voltage comparison module 11 second is patrolled Collect signal.In one embodiment, voltage comparison module 11 exports corresponding logical signal according to both comparative results and can wrapped Include：In input voltage V_INMore than or equal to reference voltage V_REFWhen export high level logic signal, and, in input voltage V_INIt is less than Reference voltage V_REFWhen export low-level logic signal.In another embodiment, voltage comparison module 11 is according to both comparison knots Fruit and exporting corresponding logical signal may include：In input voltage V_INMore than or equal to reference voltage V_REFWhen export low-level logic Signal, and, in input voltage V_INLess than reference voltage V_REFWhen export high level logic signal.

Frequency generation module is connected with counting module, for exporting count frequency to counting module, for counting module energy Corresponding counts are carried out according to count frequency.As shown in figure 8, in the present embodiment, frequency generation module 13 and counting module 12 Connection, for exporting count frequency to counting module 12, so that counting module 12 can carry out corresponding counts according to count frequency. In practical application, the count frequency that frequency generation module 13 generates is and input voltage V_INWith reference voltage V_REFRelated, example Such as, the count frequency of the generation of frequency generation module 13 is and input voltage V_INWith reference voltage V_REFPressure difference between the two is into just The relation of ratio, i.e.,：Input voltage V_INWith reference voltage V_REFPressure difference between the two is bigger, then the count frequency generated is higher； Input voltage V_INWith reference voltage V_REFPressure difference between the two is smaller, then the count frequency generated is with regard to relatively low.

Counting module is connected with voltage comparison module and frequency generation module, is exported for receiving from voltage comparison module Logical signal and frequency generation module count frequency and counted according to this, so as to generate digital controlled signal.In this reality Apply in mode, as shown in figure 8, counting module 12 is connected with voltage comparison module 11 and frequency generation module 13, come for receiving From voltage comparison module 11 export logical signal and frequency generation module 13 count frequency and counted according to this, so as to give birth to Into digital controlled signal.In actual applications, logical signal and frequency generation module from voltage comparison module output are received Count frequency and carry out according to this counting can for example including：Carried out when receiving high level logic signal plus count and connecing Carry out subtracting counting when receiving low-level logic signal.Therefore, counting module 12 is counted according to logical signal and count frequency It may include：Receive voltage comparison module 11 output logical signal be high level logic signal when, then carry out plus counting； When the logical signal for receiving the output of voltage comparison module 11 is low-level logic signal, then carry out subtracting counting.And counted During number, Count .- Duration is in then the relation of inverse ratio with count frequency, i.e.,：Count frequency is higher, then Count .- Duration is shorter； Count frequency is lower, then Count .- Duration is longer.So, with reference to foregoing middle input voltage V_INWith reference voltage V_REFTwo ginsengs Number, the trend counted substantially according to logical signal and count frequency may include following each situation.In one case, it is if defeated Enter voltage V_INMore than or equal to reference voltage V_REF, high level logic signal is exported, then carries out plus counts, and if input voltage V_INWith Reference voltage V_REFBetween pressure difference it is bigger (or smaller), then carry out plus count count frequency it is higher (or lower)；If input electricity Press V_INLess than reference voltage V_REF, low-level logic signal is exported, then carries out subtracting counting, and if input voltage V_INWith reference voltage V_REFBetween pressure difference it is bigger (or smaller), then the count frequency for carrying out subtracting counting is higher (or lower).In another scenario, If input voltage V_INMore than or equal to reference voltage V_REF, low-level logic signal is exported, then carries out subtracting counting, and if input voltage V_INWith reference voltage V_REFBetween pressure difference it is bigger (or smaller), then the count frequency for carrying out subtracting counting is higher (or lower)；It is if defeated Enter voltage V_INLess than reference voltage V_REF, high level logic signal is exported, then carries out plus counts, and if input voltage V_INWith reference Voltage V_REFBetween pressure difference it is bigger (or smaller), then carry out plus count count frequency it is higher (or lower).In this way, by counting The digital controlled signal that module 12 is generated after counting can not only integrally adapt to input voltage V_INWith reference voltage V_REFBetween Comparative result and its slow degree is and input voltage V suddenly_INWith reference voltage V_REFBetween pressure difference it is related.

D/A converter module is connected with counting module, and the digital controlled signal for being exported to counting module carries out digital-to-analogue and turned Change, generate analog control signal.In the present embodiment, as shown in figure 8, D/A converter module 14 is connected with counting module 12, Digital controlled signal for being exported to counting module 12 carries out digital-to-analogue conversion, generates analog control signal.It can be said that by number The analog control signal that mould modular converter 14 exports is for one relative to reference voltage V_REFRise and fall gradual low frequency signal, in this way, can To say that the analog control signal formed is that change is gentle in power frequency period.

Signal adjusting module, be connected with integrator and LED load, for the analog control signal that is exported according to integrator and Adjustment and the electric current of stabilized LED load.In the present embodiment, as shown in figure 8, in signal adjusting module 15 and integrator D/A converter module 14 and LED load 10 connect, and are adjusted for the analog control signal exported according to D/A converter module 14 And the electric current of stabilized LED load 10.Because the analog control signal change that D/A converter module 14 exports is gentle, therefore, by It also will be that change is gentle that signal adjusting module 15 corresponding with analog control signal, which can control the electric current of LED load 10, can disappear Except current ripples.

As shown in Figure 8, in the application LED device, not only realized by using the structure design without filter capacitor Peripheral circuit simplifies and reduces system cost on hardware, even more by detecting the input voltage of LED load, utilizes voltage ratio Compared with module 11 by input voltage compared with default reference voltage, obtain corresponding first logical signal or the second logic letter Number, then carried out the first counting when receiving the first logical signal by counting module 12 and entered when receiving the second logical signal Row second counts, and the output of counting module 12 passes through D/A converter module 14 and carries out forming simulation, elimination after digital-to-analogue conversion The control voltage signal of ripple content, then flowed through LED to adjust by signal adjusting module 15 by the control voltage signal and born 10 voltage or electric current is carried, and then causes the average current of LED load 10 to keep stable and the electric current line of LED load can be eliminated Ripple.Cause whole circuit structure compared to an external big filter capacitor on ripple chip is removed is needed in correlation technique The missings such as complexity, cost increase and crash rate increase, the application LED device have circuit structure simple, facilitating chip design, The advantages that reducing overall applicability cost and reducing crash rate.

Referring to Fig. 9, the electrical block diagram of the LED device being shown as in Fig. 8 in one embodiment.

In the embodiment in fig. 9, voltage comparison module 11 can be for example with voltage comparator, the positive of voltage comparator 11 Input is used to receive input voltage V_IN, the inverting input of voltage comparator 11 is for receiving a default reference voltage V_REF。 It should be noted that in the present embodiment, the input voltage V that voltage comparison module 11 is received_INMay be, for example, the negative of LED load 10 Terminal voltage V_DrainWith a sampled voltage V_CSDifference.Therefore, in circuit design, it is possible to provide a subtracter, the subtraction utensil There are two inputs and an output end, wherein, the negative terminal of an input and LED load is connected for receiving the negative of LED load Terminal voltage V_Drain, another input is for receiving sampled voltage V_CS, output end then be used for export LED load 10 negative terminal electricity Press V_DrainWith a sampled voltage V_CSDifference.Voltage comparator 11 is returned to, specifically, voltage comparator 11 is defeated by what is received Enter voltage V_INWith reference voltage V_REFIt is compared, and the first logical signal or the second logical signal is exported according to comparative result. In detail, voltage comparator 11 exports the first logical signal according to comparative result or the second logical signal specifically includes：When defeated Enter voltage V_INIt is greater than being equal to reference voltage V_REFWhen, then output is the first logical signal (abbreviation high level logic letter of high level Number, the high level logic signal can be exported for example " 1 ")；As input voltage V_INIt is less than reference voltage V_REFWhen, then output is low The second logical signal of level (abbreviation low-level logic signal, the low-level logic signal can be exported for example " 0 ").Certainly, on Voltage comparator 11 is stated to input voltage V_INWith reference voltage V_REFManner of comparison be merely illustrative, and be not used to limit The rights protection scope of the application, for example, in other embodiments, the inverting input of voltage comparator 11, which is used to receive, to be inputted Voltage V_IN, the normal phase input end of voltage comparator 11 is for receiving a default reference voltage V_REF, so, as input voltage V_IN It is greater than being equal to reference voltage V_REFWhen, then for low level first logical signal, (abbreviation low-level logic signal, this is low for output Level logic signal can be exported for example " 0 ")；As input voltage V_INIt is less than reference voltage V_REFWhen, then output is the of high level Two logical signals (abbreviation high level logic signal, the high level logic signal can be exported for example " 1 ").

In the embodiment in fig. 9, frequency generation module 13 can be for example with voltage controlled oscillator (Voltage-Controlled Oscillator, abbreviation VCO), the voltage controlled oscillator 13 has two inputs and an output end, wherein, an input is used for Receive input voltage V_IN, another input is for receiving reference voltage V_REF, output end is then for exporting count frequency.Due to That two inputs of voltage controlled oscillator 13 receive is input voltage V_INWith reference voltage V_REF, therefore, the count frequency of output For：F_CLK=K* | V_IN-V_REF|, wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is VCO The coefficient of frequency modulation of device.As can be seen here, the output frequency of voltage controlled oscillator 13 is and input voltage V_INWith reference voltage V_REFBetween Pressure difference is directly proportional, i.e. if input voltage V_INWith reference voltage V_REFBetween pressure difference it is bigger, then output frequency is higher；If input electricity Press V_INWith reference voltage V_REFBetween pressure difference it is smaller, then output frequency is lower.

In the embodiment in fig. 9, counting module 12 can be for example with forward-backward counter, the forward-backward counter 12 and voltage ratio Connected compared with device 11 and voltage controlled oscillator 13, for receive voltage comparator 11 output high level logic signal when according to pressure The count frequency that controlled oscillator 13 exports is carried out plus counted and receiving the low-level logic letter of the output of voltage comparator 11 Number when according to voltage controlled oscillator 13 export count frequency carry out subtracting counting.Due to forward-backward counter 12 carry out plus-minus counting be with (logical signal is and input voltage V logical signal_INWith reference voltage V_REFComparative result it is related) and count frequency (count frequency Rate is and input voltage V_INWith reference voltage V_REFBetween pressure difference it is related) it is related, thus, by counting module 12 after counting institute The digital controlled signal of generation can not only integrally adapt to input voltage V_INWith reference voltage V_REFBetween comparative result and its is steep Slow degree is and input voltage V_INWith reference voltage V_REFBetween pressure difference it is related.From the foregoing, it will be observed that by setting suitably with reference to electricity Press V_REF, may be such that output signal for one relative to reference voltage V_REFRise and fall gradual low frequency signal, has filtered out original input signal V_INIn it is possible that radio-frequency component.

In the embodiment in fig. 9, D/A converter module 14 can use conventional digital analog converter (Digital to Analog Converter, abbreviation DAC), the digital analog converter 14 is connected with forward-backward counter 12, for by forward-backward counter 12 Carry out plus count and subtract and count exported digital controlled signal progress digital-to-analogue conversion, generation analog control signal V_COMP.Can be with Say, the analog control signal V exported by D/A converter module 14_COMPChange in power frequency period gentle.

In the embodiment in fig. 9, signal adjusting module 15 can more further comprise amplifier 151 and adjustment pipe 152, its In, amplifier 151 can be for example with operational amplifier, and adjusting pipe 152 can then use power transistor (herein, brilliant with NMOS Exemplified by body pipe), the first input end of operational amplifier 151 is connected defeated for receiving digital analog converter 14 with digital analog converter 14 The analog control signal V gone out_COMP, the second input of operational amplifier 151 be connected with the source electrode of nmos pass transistor 152 for Receive the sampled voltage V of the source electrode from nmos pass transistor 152_CS, output end and the nmos pass transistor 152 of operational amplifier 151 Grid connection, the drain electrode of nmos pass transistor 152 is connected with LED load 10 and exports the negative terminal voltage V of LED load 10_Drain, The source electrode of nmos pass transistor 152 passes through a sampling resistor R_CSAnd it is connected with ground terminal and exports sampled voltage V_CS.In the present embodiment In, be the normal phase input end using operational amplifier 151 as first input end, and by the inverting input of operational amplifier 151 As the second input.In addition, the output end of operational amplifier 151 by after nmos pass transistor 152 with operational amplifier 151 Inverting input connection is to form a negative-feedback (Negative Feedback) configuration so that operational amplifier 151 it is anti-phase Input samples to obtain the electric current of nmos pass transistor, it is ensured that the stable running of circuit.Using operational amplifier 151, may be such that Operational amplifier 151 export voltage regulation signal be and analog control signal V_COMPIt is synchronised, and numerically direct proportionality. Signal adjusting module by taking nmos pass transistor 152 as an example can realize the linear stable of signal according to voltage regulation signal again.

For aforementioned opamp 151, the simulation control that digital analog converter 14 exports is received by operational amplifier 151 Signal V processed_COMP, according to the analog control signal V_COMPWith the feedback signal of the source electrode of nmos pass transistor 152, output voltage stabilizing letter Number, wherein, the voltage regulation signal of output is the analog control signal V with two inputs_COMPWith the voltage difference of feedback signal into just Than.For nmos pass transistor 152, the voltage regulation signal that is exported by operational amplifier 151 is adjustable to flow through nmos pass transistor 152 Interior electric current, due to analog control signal V_COMPChange is gentle, therefore, by with analog control signal V_COMPCorresponding voltage regulation signal The electric current I in nmos pass transistor 152 controlled_MAlso it will be that change is gentle, eliminate current ripples.Born due to flowing through LED Carry 10 driving current I_LEqual to electric current I_M, therefore, driving current I_LAlso eliminate current ripples.

It should be noted that in the electrical block diagram of the LED device shown in Fig. 9, signal adjusting module 15 includes Amplifier 151 and adjustment pipe 152, but be not limited thereto, in other embodiments, signal adjusting module 15 can still make other changes More, such as：Signal adjusting module may include adjustment pipe, and the adjustment is managed between the LED load and ground terminal, wherein, institute Nmos pass transistor can be used by stating adjustment pipe, and the grid of the nmos pass transistor is connected with the output end of digital analog converter 14, described The drain electrode of nmos pass transistor and the negative terminal of LED load connect and are used as the output end of the negative terminal voltage of LED load 10, the NMOS The source electrode of transistor can be connected by a resistance with ground terminal.

Further, the application LED device may also include overvoltage crowbar (Over-Voltage Protection, OVP), The overvoltage crowbar is configured between the drain electrode of nmos pass transistor 152 and the first input end of operational amplifier 151.

As shown in Figure 9, in the application LED device, not only realized by using the structure design without filter capacitor Peripheral circuit simplifies and reduces system cost on hardware, is even more used as input voltage V by detecting LED negative terminal voltages_IN, profit With voltage comparator 11 by input voltage V_INWith default reference voltage V_REFIt is compared, obtains corresponding first logical signal Or second logical signal, then carry out when receiving the first logical signal by forward-backward counter 12 first counting and receiving the Carry out second during two logical signals to count, the output of forward-backward counter 12 passes through shape after the progress digital-to-analogue conversion of digital analog converter 14 Pass through the He of operational amplifier 151 into simulation, the control voltage signal that eliminates ripple content, then by the control voltage signal Nmos pass transistor adjusts the electric current in nmos pass transistor, and then causes the average current of LED load to keep stable and can eliminate The current ripples of LED load.Led compared to an external big filter capacitor on ripple chip is removed is needed in correlation technique Causing the complexity, cost increase and crash rate of whole circuit structure the missing such as increases, the application LED current ripple eliminate circuit and Comprising LED current ripple eliminate circuit LED device have circuit structure simple, facilitating chip design, reduce overall applicability into Originally the advantages that and reducing crash rate.

Referring to Fig. 10, it is shown as the schematic flow sheet of the application LED current ripple removing method in one embodiment. As shown in Figure 10, the application LED current ripple removing method may include following steps：

Step S101, obtain the input voltage related to LED load, by input voltage compared with a reference voltage simultaneously Corresponding logical signal is exported according to both comparative results.In the present embodiment：Obtain the input electricity related to LED load Pressure, including：The negative terminal voltage of LED load is detected, using the difference of the negative terminal voltage and a sampled voltage as input voltage, or Person, the negative terminal voltage of LED load is detected, using the negative terminal voltage as input voltage.By the input voltage and one with reference to electricity Pressure is compared and corresponding logical signal is exported according to both comparative results, including：The input voltage and one are joined Examine voltage to be compared, the first logical signal is exported when the input voltage is more than or equal to the reference voltage, and, in institute State when input voltage is less than the reference voltage and export the second logical signal.Foregoing the first logical signal and the second logical signal It can be adjusted in good time according to circuit design, for example, in one case, first logical signal may be, for example, high level logic letter Number, and second logical signal may be, for example, low-level logic signal；In another scenario, first logical signal can be such as For low-level logic signal, and second logical signal may be, for example, high level logic signal.

Step S103, logic-based signal are counted, and generate digital controlled signal.In the present embodiment, based on described Logical signal is counted, including：Carried out plus counted based on high level logic signal and carried out based on low-level logic signal Subtract counting.As it was previously stated, in one case, if the first logical signal is, for example, high level logic signal, carries out plus count； If the second logical signal is, for example, low-level logic signal, carry out subtracting counting；And in another scenario, if the first logic is believed Number be, for example, low-level logic signal, then carry out subtracting counting；If the second logical signal is, for example, high level logic signal, carry out Add counting.

It is worth noting that, when being counted, the count frequency being based on is close with input voltage and reference voltage Related.In the present embodiment, the count frequency is generated using below equation：F_CLK=K* | V_IN-V_REF|, wherein, F_CLKFor Count frequency, V_INFor input voltage, V_REFFor reference voltage, K is the coefficient of frequency modulation of voltage controlled oscillator.

Step S105, digital-to-analogue conversion, the gentle analog control signal of generation fluctuating are carried out to digital controlled signal.In this reality Apply in example, digital-to-analogue conversion carried out to the digital controlled signal, it may include：The digital controlled signal for counting gained will be added to enter line number The analog control signal of rising is formed after mould conversion, will be subtracted and be counted the digital controlled signal of gained and carry out under being formed after digital-to-analogue conversion The analog control signal of drop.Specifically, usually, when LED drive circuit is stable, in a power frequency period, The number for adding counting is identical with the number for subtracting counting, in this way, increase of the analog control signal of output in a power frequency period Amount and decrement are also equal, and analog control signal overall variation is gentle.

Step S107, according to analog control signal, adjust the voltage or electric current of LED load so that the average electricity of LED load Stream keeps stable and can eliminate the current ripples of LED load.In the present embodiment, because analog control signal is and input voltage Related, and input voltage is related to the voltage and current of LED load, therefore, directly passes through analog control signal or root The voltage or electric current of LED load are just can adjust according to analog control signal so that the voltage or electric current of LED load are stable and can eliminate The current ripples of LED load.

The application LED current ripple removing method, input voltage and reference voltage is compared and the ratio according to both Relatively result and export corresponding logical signal, counted according to logical signal and count frequency corresponding digital control to be formed Signal, then digital controlled signal is subjected to digital-to-analogue conversion to form analog control signal, the voltage or electric current of LED load are adjusted, So that the average current of the LED load keeps stable and can eliminate the current ripples of LED load.

Below in conjunction with Fig. 9 and Figure 10, to illustrate stream of the LED device shown in Fig. 9 in being eliminated applied to LED current ripple Journey may include：

Obtain the input voltage related to LED load, by the input voltage compared with default reference voltage simultaneously The first logical signal or the second logical signal are exported according to comparative result.Specifically, using voltage comparator 11, input is received Voltage V_INWith reference voltage V_REF, by input voltage V_INWith reference voltage V_REFIt is compared, shows input voltage in comparative result V_INMore than or equal to reference voltage V_REFWhen export the first logical signal, show input voltage V in comparative result_INLess than reference voltage V_REFWhen export the second logical signal.Foregoing the first logical signal and the second logical signal can be adjusted in good time according to circuit design It is whole, for example, in the present embodiment, in the LED device shown in Fig. 9, the normal phase input end of voltage comparator 11 is defeated for receiving Enter voltage V_IN, the inverting input of voltage comparator 11 is for receiving a default reference voltage V_REF, as input voltage V_INIt is More than or equal to reference voltage V_REFWhen, then output for high level logic signal as the first logical signal, as input voltage V_INIt is small In reference voltage V_REFWhen, then output is low-level logic signal as the second logical signal.The first foregoing logical signal and Two logical signals can adjust in good time according to circuit design, if for example, the inverting input of voltage comparator 11 is defeated for receiving Enter voltage V_IN, the normal phase input end of voltage comparator 11 is for receiving a default reference voltage V_REF, as input voltage V_INIt is More than or equal to reference voltage V_REFWhen, then output for low-level logic signal as the first logical signal, as input voltage V_INIt is small In reference voltage V_REFWhen, then output is high level logic signal as the second logical signal.In addition, in the present embodiment, voltage The input voltage V that comparison module 11 is received_INMay be, for example, the negative terminal voltage V of LED load 10_DrainWith a sampled voltage V_CS's Difference.

Carry out the first counting according to first logical signal and carry out second according to second logical signal to count, First counting and the second count frequency counted are directly proportional to the difference of input voltage and reference voltage.In the present embodiment In, the comparative result exported using the receiving voltage comparator 11 of forward-backward counter 12 is counted accordingly, i.e. receiving Carry out first when stating the first logical signal to count and carry out the second counting when receiving second logical signal, so as to raw Into digital controlled signal.If make following hypothesis：Carry out plus count when receiving high level logic signal and be low receiving Carry out subtracting counting during level logic signal.So, in the present embodiment, in the LED device shown in Fig. 9, according to described first Logical signal carry out first count and according to second logical signal carry out second count particularly as including：In comparative result When first logical signal of output is high level logic signal, then carries out plus count；In the second logic letter of comparative result output When number being low-level logic signal, then carry out subtracting counting.Certainly, other changes can still be made in other embodiments, for example, at it In his change case, carry out first according to first logical signal and count and according to the meter of second logical signal progress second Number can also include：When the first logical signal of comparative result output is low-level logic signal, then carry out subtracting counting；Than When second logical signal of relatively result output is high level logic signal, then carries out plus count.

In addition, the count frequency that forward-backward counter 12 carries out plus-minus counting is according to input voltage V_INWith reference voltage V_REF It is related, i.e. the count frequency is and input voltage V_INWith reference voltage V_REFDifference between the two is directly proportional, i.e. if defeated Enter voltage V_INWith reference voltage V_REFPressure difference it is bigger, then required count frequency is higher；If input voltage V_INWith reference electricity Press V_REFPressure difference it is smaller, then required count frequency is lower.

Analog control signal is generated based on count results.In the present embodiment, it will be added and subtracted and counted using digital analog converter 14 Number device 12 carries out the first counting digital controlled signal exported with the second counting and carries out digital-to-analogue conversion, generates analog control signal V_COMP.Specifically, the analog control signal of rising will be formed after the digital controlled signal progress digital-to-analogue conversion for adding counting gained, will Subtract count gained digital controlled signal carry out digital-to-analogue conversion after form the analog control signal of decline.Specifically, Usually, when LED drive circuit is stable, in a power frequency period, the number for adding counting is identical with the number for subtracting counting, such as This, the analog control signal V of output_COMPIncrementss and decrement in a power frequency period are also equal.

Voltage regulation signal is exported based on analog control signal.In the present embodiment, received and simulated using operational amplifier 151 Control signal V_COMPWith feedback signal (that is, the sampled voltage V from nmos pass transistor 152_CS), analog control signal is calculated V_COMPWith the sampled voltage V as feedback signal_CSDifference, will the difference carry out gain amplification disposal after obtain voltage regulation signal. The voltage regulation signal of output is and analog control signal V_COMPIt is synchronised, and numerically direct proportionality.Using voltage regulation signal, Obtain stable driving current.In the present embodiment, the voltage regulation signal exported by operational amplifier 151, adjustment flow through NMOS crystalline substances Electric current in body pipe 152, and then adjust the electric current and voltage of LED load.Due to analog control signal V_COMPChange is gentle, because This, by with analog control signal V_COMPThe electric current in nmos pass transistor 152 that corresponding voltage regulation signal is controlled also will be change Gentle, eliminate current ripples and cause the average current in nmos pass transistor 152 to keep stable.Due to flowing through LED load 10 driving current is equal to the electric current in nmos pass transistor 152, therefore, also eliminates current ripples and causes the flat of LED load Equal electric current keeps stable.

Therefore, in the application LED device, the input voltage V that is received by integrator_INIncrease, after integrated device processing The analog control signal V of output_COMPIncrease, flow through the electric current increase of nmos pass transistor, sampled voltage V_CSIncrease, drags down LED and bears Carry 10 negative terminal voltage V_Drain, input voltage V_INReduce；The input voltage V received by integrator_INReduce, at integrated device The analog control signal V exported after reason_COMPReduce, the electric current for flowing through nmos pass transistor reduces, sampled voltage V_CSReduce, LED is born Carry 10 negative terminal voltage V_DrainIncrease, input voltage V_INIncrease.So, it can be ensured that the voltage and average current at LED load both ends Keep stable.

In addition, for nmos pass transistor 152, the voltage regulation signal that is exported by operational amplifier 151 is adjustable to be flowed through Electric current in nmos pass transistor 152, due to analog control signal V_COMPChange is gentle, therefore, by with analog control signal V_COMPIt is right The electric current I in nmos pass transistor 152 that the voltage regulation signal answered is controlled_MAlso it will be that change is gentle, eliminate current ripples.By In the driving current I for flowing through LED load 10_LEqual to electric current I_M, therefore, driving current I_LAlso eliminate current ripples.

Figure 11 is referred to, is shown as the structure chart of the application LED device in another embodiment.As shown in figure 11, exist In present embodiment, the application LED device includes：LED load 10, rectifier bridge 21, the first electric capacity C1, energy storage inductor L, afterflow two Pole pipe D, the second electric capacity C2, LED driver.

The input of rectifier bridge 21 is electrically connected to an AC power, for being direct current by AC rectification.In this implementation In mode, rectifier bridge 21 constructs for full-bridge type, and full-bridge is to be connected by four commutation diodes by the form of full-wave bridge rectifier circuit Connect and the composition that is packaged as a whole.

First electric capacity C1 both ends are respectively electrically connected to two rectification branch roads in parallel in rectifier bridge 21, for direct current It is filtered.

Second electric capacity C2 is in parallel with LED load 10, i.e. and the second electric capacity C2 first end is connected with the anode of LED load 10, Second electric capacity C2 the second end is connected with the negative terminal of LED load 10 and is connected with ground terminal.

Energy storage inductor L connects with sustained diode, and the other end of energy storage inductor is coupled to a rectification branch of rectifier bridge 21 Road, the other end of sustained diode are connected with the anode of LED load 10.

LED driver is arranged between LED load 10 and energy storage inductor L, for controlling the average current of LED load 10 not Become.In the present embodiment, LED driver is integrated with a LED drive chip.The LED drive chip may include：Power supply Hold HV, voltage input end IN, control signal end COMP, current detecting end CS, ground terminal connection end GND and switching signal end SW. Power end HV is used to obtain supply voltage, with each circuit or component offer power supply in applied to APFC control chips. Voltage input end IN is connected with the negative terminal of LED load 10, for receiving the negative terminal voltage of LED load to be used as input voltage, reality On border, the negative terminal voltage is the voltage for the sampling resistor R that LED load 10 electrically connects.Switching signal end SW and a power Pipe M connections, power tube M is controlled for being controlled by the control signal of control signal end COMP outputs.

LED driver in LED drive chip more may include foregoing integrator and a signal adjusting module, its In, the input voltage in the integrator is LED negative terminal voltages.In one embodiment, the input voltage in the integrator with The voltage for the sampling resistor R that LED load 10 electrically connects, sampling resistor R other end ground connection, the signal adjusting module and institute The output end and LED load 10 for stating integrator connect, and the analog control signal for being exported according to the integrator causes LED to bear The average current of load 10 is constant.

As shown in Figure 11, in the application LED device, due to being integrated with LED driver in LED drive chip, and LED drives Include integrator and signal adjusting module in dynamic device, the flat of LED load 10 is can ensure that using integrator and signal adjusting module Equal electric current is constant, and therefore, the application LED device, which can remove from, configures big filter capacitor, realizes the simplification of peripheral circuit, reduces System cost, Problem of Failure caused by thoroughly eliminating peripheral filter electric capacity.

Figure 12 is referred to, is shown as the electrical block diagram of LED device in one embodiment in Figure 11.

The application LED device includes：LED load 10, rectifier bridge 21, the first electric capacity C1, energy storage inductor L, fly-wheel diode D, the second electric capacity C2, LED driver.

LED load 10 can be made up of a LED or multiple LEDs, and being also associated with one between LED load 10 and ground terminal adopts Sample resistance R.

LED driver is arranged between LED load 10 and energy storage inductor L, for controlling the average current of LED load 10 not Become.In the present embodiment, the LED driver may include foregoing integrator and a signal adjusting module, the product Device is divided more to may include voltage comparison module 21, counting module 22, frequency generation module 23 and D/A converter module 24.

Voltage comparison module 21 is used to receive input voltage V_INWith reference voltage V_REF, by input voltage V_INWith reference voltage V_REFIt is compared and corresponding logical signal is exported according to both comparative results.It should be noted that in present embodiment In, input voltage V that voltage comparison module 21 is received_INMay be, for example, the negative terminal voltage of LED load 10 (in fact, described negative Terminal voltage is the voltage for the sampling resistor R that LED load 10 electrically connects, and one end of the sampling resistor is connected with LED load, its The other end is connected with ground terminal).In the fig. 12 embodiment, voltage comparison module 21 can be for example with voltage comparator, voltage ratio Inverting input compared with device 21 is connected for receiving input voltage V with the negative terminal of LED load 10_IN, voltage comparator 21 is just Phase input is used to receive a default reference voltage V_REF.The input voltage V that voltage comparator 21 will receive_INWith reference electricity Press V_REFIt is compared, and the first logical signal or the second logical signal is exported according to comparative result.In detail, voltage ratio compared with Device 21 exports the first logical signal according to comparative result or the second logical signal specifically includes：As input voltage V_INIt is greater than In reference voltage V_REFWhen, then output is low level first logical signal (abbreviation low-level logic signal, the low-level logic Signal can be exported for example " 0 ")；As input voltage V_INIt is less than reference voltage V_REFWhen, then output is believed for the second logic of high level Number (abbreviation high level logic signal, the high level logic signal can be exported for example " 1 ").Certainly, above-mentioned voltage comparator 21 is right Input voltage V_INWith reference voltage V_REFManner of comparison be merely illustrative, and be not used to limit the application rights protection Scope, for example, in other embodiments, the positive input terminal of voltage comparator 21 is connected with the negative terminal of LED load 10 for connecing Receive input voltage V_IN, the negative input end of voltage comparator 21 is for receiving a default reference voltage V_REF.Voltage comparator 21 will The input voltage V received_INWith reference voltage V_REFIt is compared, and the first logical signal or is exported according to comparative result Two logical signals.In detail, voltage comparator 21 exports the first logical signal or the second logical signal tool according to comparative result Body includes：As input voltage V_INIt is greater than being equal to reference voltage V_REFWhen, then output is the first logical signal (abbreviation of high level High level logic signal, the high level logic signal can be exported for example " 1 ")；As input voltage V_INIt is less than reference voltage V_REF When, then for low level second logical signal, (abbreviation low-level logic signal, the low-level logic signal can be exported for example for output “0”)。

Frequency generation module 23 is connected with counting module 22, for exporting count frequency to counting module 22, for counting Module 22 can carry out corresponding counts according to count frequency.In actual applications, the count frequency of the generation of frequency generation module 23 is With input voltage V_INWith reference voltage V_REFRelated.In the fig. 12 embodiment, frequency generation module 23 can be for example with voltage-controlled Oscillator (Voltage-Controlled Oscillator, abbreviation VCO), the voltage controlled oscillator 23 have two inputs and one Output end, wherein, an input is used to receive input voltage V_IN, another input is for receiving reference voltage V_REF, output End is then used to export count frequency.Due to voltage controlled oscillator 23 two inputs receive be input voltage V_INAnd reference voltage V_REF, therefore, the count frequency of output is：F_CLK=K* | V_IN-V_REF|, wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is the coefficient of frequency modulation of voltage controlled oscillator.As can be seen here, the output frequency of voltage controlled oscillator 23 is and input Voltage V_INWith reference voltage V_REFBetween pressure difference it is directly proportional, i.e. if input voltage V_INWith reference voltage V_REFBetween pressure difference get over Greatly, then output frequency is higher；If input voltage V_INWith reference voltage V_REFBetween pressure difference it is smaller, then output frequency is lower.

Counting module 22 is connected with voltage comparison module 21 and frequency generation module 23, for receiving from voltage ratio compared with mould The logical signal of the output of block 21 and the count frequency of frequency generation module 23 are simultaneously counted according to this, so as to generate digital control letter Number.In the fig. 12 embodiment, counting module 22 can be for example with forward-backward counter, the forward-backward counter 22 and voltage comparator 21 and voltage controlled oscillator 23 connect, for being shaken when receiving the high level logic signal of the output of voltage comparator 11 according to voltage-controlled The count frequency for swinging the output of device 13 is carried out plus counted and when receiving the low-level logic signal of the output of voltage comparator 11 Carry out subtracting counting according to the count frequency that voltage controlled oscillator 13 exports.It is and logic because forward-backward counter 22 carries out plus-minus counting (logical signal is and input voltage V signal_INWith reference voltage V_REFComparative result it is related) and count frequency (count frequency is With input voltage V_INWith reference voltage V_REFBetween pressure difference it is related) it is related, thus, generated by counting module 22 after counting Digital controlled signal can not only integrally adapt to input voltage V_INWith reference voltage V_REFBetween comparative result and its slow journey suddenly Degree is and input voltage V_INWith reference voltage V_REFBetween pressure difference it is related.From the foregoing, it will be observed that by setting suitable reference voltage V_REF, may be such that output signal for one relative to reference voltage V_REFRise and fall gradual low frequency signal, has filtered out original input signal V_IN In it is possible that radio-frequency component.

D/A converter module 24 is connected with counting module 22, is exported for the count results exported based on counting module 22 Analog control signal.In the fig. 12 embodiment, D/A converter module 24 can use conventional digital analog converter (Digital to Analog Converter, abbreviation DAC), the digital analog converter 24 is connected with forward-backward counter 22, for by forward-backward counter 22 Carry out plus count and subtract and count exported digital controlled signal progress digital-to-analogue conversion, generation analog control signal V_COMP.Can be with Say, the analog control signal V exported by D/A converter module 24_COMPChange in power frequency period gentle.

Signal adjusting module is connected with D/A converter module 24 and LED load 10, for defeated according to D/A converter module 24 The analog control signal gone out make it that the average current of LED load 10 is constant.Further, signal adjusting module more may include pulse Width modulator 25 and switching tube 26, wherein, pulse-width modulator 25 is connected with D/A converter module 24, for according to digital-to-analogue Analog control signal that modular converter 24 exports and carry out the pulse width modulation of signal to generate switch controlled signal, switch Pipe 26 is connected with pulse-width modulator 25, is carried out for the switch controlled signal exported according to pulse-width modulator 25 ON/OFF operates.In the fig. 12 embodiment, pulse-width modulator 25 can use a PWM comparators, and switching tube 26 can be adopted Use nmos pass transistor.The first input end of PWM comparators 25 is connected with digital analog converter 24, and the second input is used to receive a saw Either triangular signal (sawtooth waveforms or triangular signal can be for example by the oscillator generations) of tooth ripple, PWM comparators 25 Output end be connected with the grid of nmos pass transistor 26, the source electrode of nmos pass transistor 26 passes through a sampling resistor R_CSConnect with ground terminal Connect, the drain electrode of nmos pass transistor 26 is connected with power tube M.In this way, the simulation that PWM comparators 25 can export digital analog converter 24 Control signal V_COMPTo generate control signal compared with the sawtooth waveforms or triangular signal, so as to adjust NMOS crystal The ON time of pipe 26.In the fig. 12 embodiment, what the normal phase input end of PWM comparators 25 received is analog control signal V_COMP, the inverting input reception of PWM comparators 25 is sawtooth waveforms or triangular signal, by being carried out to both signals Compare, PWM comparators 25 are in analog control signal V_COMPOutput pulse signal is with shape during more than sawtooth waveforms or triangular signal Into the control signal for controlling nmos pass transistor 26 to turn on, wherein, the width of the pulse signal (i.e. control signal) of output is Analog control signal V during depending on the pulse falling edge moment_COMP, the width of pulse signal is bigger, then nmos pass transistor 26 is led The logical duration is longer.

Therefore, in the application LED device, when the electric current increase of LED load 10, the input received by integrator is electric Press V_INIncrease, the analog control signal V exported after integrated device processing_COMPReduce, the control letter of pulse-width modulator output Number pulse width reduce, switching tube ON time reduce, energy storage inductor electric current reduce, flow through LED load 10 electric current reduce, Input voltage V_INReduce；When the electric current of LED load 10 is reduced, the input voltage V that is received by integrator_INReduce, it is integrated The analog control signal V exported after device processing_COMPIncrease, the pulse width of the control signal of pulse-width modulator output increase Add, the increase of switching tube ON time, the increase of energy storage inductor electric current, flow through the electric current increase of LED load 10, input voltage V_INIncrease Add.So, it can be ensured that the average current inside LED load keeps stable.

Further, since analog control signal V_COMPChange gently within the cycle, eliminate current ripples, therefore, may be such that The electric current of LED load 10 is flowed through, therefore, the electric current of LED load 10 can also eliminate current ripples.

Below in conjunction with Figure 10 and Figure 12, to illustrate the LED device shown in Figure 12 in being eliminated applied to LED current ripple Flow may include：

Obtain the input voltage related to LED load, by the input voltage compared with default reference voltage simultaneously The first logical signal or the second logical signal are exported according to comparative result.In the present embodiment, in the LED device shown in Figure 12 In, using voltage comparator 21, receive input voltage V_INWith reference voltage V_REF, by input voltage V_INWith reference voltage V_REFEnter Row compares, and shows input voltage V in comparative result_INMore than or equal to reference voltage V_REFWhen output be low-level logic signal conduct First logical signal, show input voltage V in comparative result_INLess than reference voltage V_REFWhen output for high level logic signal make For the second logical signal.Foregoing the first logical signal and the second logical signal can adjust in good time according to circuit design, for example, If the normal phase input end of voltage comparator 11 is used to receive input voltage V_IN, the inverting input of voltage comparator 11 is for receiving One default reference voltage V_REF, as input voltage V_INIt is greater than being equal to reference voltage V_REFWhen, then output is believed for high level logic Number logical signal of conduct first, as input voltage V_INIt is less than reference voltage V_REFWhen, then output is low-level logic signal conduct Second logical signal.In addition, in the present embodiment, the input voltage V that voltage comparison module 11 is received_INMay be, for example, that LED is born Carry 10 negative terminal voltage (in fact, the negative terminal voltage is the voltage for the sampling resistor R that LED load 10 electrically connects).

Carry out the first counting according to first logical signal and carry out second according to second logical signal to count, First counting and the second count frequency counted are directly proportional to the difference of input voltage and reference voltage.In the present embodiment In, the comparative result exported using the receiving voltage comparator 21 of forward-backward counter 22 is counted accordingly, i.e. receiving Carry out first when stating the first logical signal to count and carry out the second counting when receiving second logical signal, so as to raw Into digital controlled signal.If make following hypothesis：Carry out plus count when receiving high level logic signal and be low receiving Carry out subtracting counting during level logic signal.So, in the present embodiment, in the LED device shown in Figure 12, according to described first Logical signal carry out first count and according to second logical signal carry out second count particularly as including：In comparative result When first logical signal of output is low-level logic signal, then carry out subtracting counting；In the second logic letter of comparative result output When number being high level logic signal, then carry out plus count.Certainly, other changes can still be made in other embodiments, for example, at it In his change case, carry out first according to first logical signal and count and according to the meter of second logical signal progress second Number can also include：When the first logical signal of comparative result output is high level logic signal, then carries out plus count；Than When second logical signal of relatively result output is low-level logic signal, then carry out subtracting counting.

In addition, the count frequency that forward-backward counter 22 carries out plus-minus counting is according to input voltage V_INWith reference voltage V_REF It is related, i.e. the count frequency is and input voltage V_INWith reference voltage V_REFDifference between the two is directly proportional, i.e. if defeated Enter voltage V_INWith reference voltage V_REFPressure difference it is bigger, then required count frequency is higher；If input voltage V_INWith reference electricity Press V_REFPressure difference it is smaller, then required count frequency is lower.

Analog control signal is generated based on count results.In the present embodiment, it will be added and subtracted and counted using digital analog converter 24 Number device 22 carries out the first counting digital controlled signal exported with the second counting and carries out digital-to-analogue conversion, generates analog control signal V_COMP.Specifically, the analog control signal of rising will be formed after the digital controlled signal progress digital-to-analogue conversion for adding counting gained, will Subtract count gained digital controlled signal carry out digital-to-analogue conversion after form the analog control signal of decline.Specifically, Usually, when LED drive circuit is stable, in a power frequency period, first counts the number and second of (such as plus counting) The number of counting (such as subtracting counting) is identical, in this way, the analog control signal V of output_COMPIncrease in a power frequency period Amount and decrement are also equal.

Voltage regulation signal is exported based on analog control signal.In the present embodiment, received and simulated using operational amplifier 151 Control signal V_COMPWith the feedback signal (that is, sampled voltage) from nmos pass transistor 152, analog control signal is calculated V_COMPWith as feedback signal sampled voltage V_CSDifference, will the difference carry out gain amplification disposal after obtain voltage regulation signal.It is defeated The voltage regulation signal gone out is and analog control signal V_COMPIt is synchronised, and numerically direct proportionality.Using voltage regulation signal, obtain The driving current that must stablize.In the present embodiment, the voltage regulation signal exported by operational amplifier 151, adjustment flow through NMOS crystal Electric current in pipe 152.Due to analog control signal V_COMPChange is gentle, therefore, by with analog control signal V_COMPCorresponding voltage stabilizing The electric current in nmos pass transistor 152 that signal is controlled also will be that change is gentle, eliminate current ripples.Due to flowing through LED The driving current of load 10 is equal to the electric current in nmos pass transistor 152, therefore, also eliminates current ripples.

From the foregoing, it will be observed that in the application LED device, not only realized by using the structure design without filter capacitor hard Peripheral circuit simplifies and reduces system cost on part, even more by detecting the negative terminal voltage of LED load, using voltage ratio compared with Device 21 is by input voltage V_INWith default reference voltage V_REFIt is compared, obtains corresponding first logical signal or the second logic Signal, then carry out the first counting when receiving the first logical signal by forward-backward counter 22 and receiving the second logical signal Shi Jinhang second is counted, and the output of forward-backward counter 22 carries out the control of formation simulation after digital-to-analogue conversion by digital analog converter 24 Voltage signal processed, corresponding pulse-width signal is exported further according to the control voltage signal, work(is controlled by pulse-width signal The break-make of rate switching tube and break-make duration, the electric current of LED load is adjusted, and then the average current in LED load is protected Keep steady and determine and can eliminate the current ripples of LED load so that LED device can obtain higher power factor.Compared to related skill An external big filter capacitor on ripple chip is removed is needed in art and causes the complexity of whole circuit structure, cost increase And the missing such as crash rate increase, the application LED current ripple eliminates circuit and the LED comprising LED current ripple elimination circuit is set It is standby that there is simple circuit structure, facilitating chip design, reduce overall applicability cost and reduce crash rate.

The principle and its effect of above-described embodiment only illustrative the application, not for limitation the application.It is any ripe Know the personage of this technology all can without prejudice to spirit herein and under the scope of, modifications and changes are carried out to above-described embodiment.Cause This, those of ordinary skill in the art is complete without departing from spirit disclosed herein and institute under technological thought such as Into all equivalent modifications or change, should be covered by claims hereof.

Claims

A kind of 1. integrator, it is characterised in that including：

Voltage comparison module, for receiving input voltage and reference voltage, the input voltage and the reference voltage are carried out Compare and corresponding logical signal is exported according to both comparative results；

Counting module, it is connected with the voltage comparison module, the logical signal for being exported according to the voltage comparison module enters Row counts, and generates digital controlled signal；And

D/A converter module, it is connected with the counting module, the digital controlled signal for being exported to the counting module is carried out Digital-to-analogue conversion, generate analog control signal.
2. integrator according to claim 1, it is characterised in that

The voltage comparison module exports corresponding logical signal according to both comparative results, including：In the input electricity Pressure exports the first logical signal when being more than or equal to the reference voltage, and, it is less than the reference voltage in the input voltage When export the second logical signal；And

The logical signal that the counting module exports according to the voltage comparison module is counted, including：It is described receiving First is carried out during the first logical signal to count and carry out the second counting when receiving second logical signal.
3. integrator according to claim 1 or 2, it is characterised in that the counting module is according to the voltage ratio compared with mould The logical signal of block output is counted, including：Carried out when receiving high level logic signal plus count and receiving Carry out subtracting counting during low-level logic signal.
4. integrator according to claim 3, it is characterised in that in a power frequency period, described plus counting number Identical with the number for subtracting counting, the incrementss and decrement of the digital controlled signal are equal.
5. integrator according to claim 1, it is characterised in that also including frequency generation module, with the counting module Connection, for exporting count frequency to the counting module.
6. integrator according to claim 5, it is characterised in that

The frequency generation module is voltage controlled oscillator, has two inputs and an output end, wherein, an input is used to connect The input voltage is received, another input is used to receive the reference voltage, and the output end is used to export count frequency；

The count frequency is generated using below equation：

F_CLK=K* | V_IN-V_REF|

Wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is the coefficient of frequency modulation of voltage controlled oscillator.
7. a kind of LED current ripple eliminates circuit, it is characterised in that including：

Integrator as any one of claim 1 to 6；Input voltage in the integrator is the negative terminal of LED load The difference of voltage and a sampled voltage；And

Signal adjusting module, it is connected with the D/A converter module in the integrator and the LED load, for according to the number Mould modular converter output analog control signal and adjust the voltage or electric current of LED load so that the average electricity of the LED load Stream keeps stable.
8. LED current ripple according to claim 7 eliminates circuit, it is characterised in that the signal adjusting module includes Adjustment pipe between the LED load and ground terminal, the output of the control terminal and the D/A converter module of the adjustment pipe End connection.
9. LED current ripple according to claim 8 eliminates circuit, it is characterised in that the adjustment pipe is NMOS crystal Pipe, the grid of the MOS transistor is connected with the output end of the D/A converter module, the drain electrode of the nmos pass transistor and The negative terminal of LED load connects and is used as the output end of the negative terminal voltage of LED load.
10. LED current ripple according to claim 7 eliminates circuit, it is characterised in that the signal adjusting module includes Amplifier and adjustment are managed, and the amplifier is connected with the D/A converter module, for being exported according to the D/A converter module Analog control signal and a sampled voltage carry out signal enhanced processing after generate voltage regulation signal, the adjustment pipe and the amplification Device and LED load are electrically connected, for the electric current of the LED load to be adjusted and stablized according to the voltage regulation signal.
11. LED current ripple according to claim 10 eliminates circuit, it is characterised in that the amplifier is put for computing Big device, the adjustment pipe is nmos pass transistor, wherein, the output end of the grid of the nmos pass transistor and the operational amplifier Connection, the drain electrode of the nmos pass transistor and the negative terminal of LED load connect and are used as the output end of the negative terminal voltage of LED load, The source electrode of the nmos pass transistor connects ground terminal by a sampling resistor and is used as the output end of the sampled voltage, the computing The first input end of amplifier is connected with the output end of the D/A converter module, the second input of the operational amplifier with The source electrode connection of the nmos pass transistor.
12. a kind of LED ripples eliminate chip, it is characterised in that including：

LED ripples as any one of claim 7 to 11 eliminate circuit or such as any one of claim 1 to 6 institutes The integrator stated.
A kind of 13. LED driver, it is characterised in that including：

Such as the integrator of any one of claim 1 to 6；Input voltage in the integrator is LED negative terminal voltages；And

Signal adjusting module, it is connected with the D/A converter module in the integrator and the LED load, for according to the number The analog control signal of mould modular converter output and adjust the voltage or electric current of the LED load so that the LED load it is flat Equal electric current keeps stable.
14. LED driver according to claim 13, it is characterised in that the signal adjusting module includes pulse width Modulator and switching tube, wherein, the pulse-width modulator is connected with the D/A converter module, for according to the digital-to-analogue The analog control signal of modular converter output and carry out the pulse width modulation of signal to generate switch controlled signal, it is described to open Pulse-width modulator described in Guan Guanyu connects, for the switch controlled signal that is exported according to the pulse-width modulator Carry out ON/OFF operation.
15. LED driver according to claim 14, it is characterised in that the pulse-width modulator is a comparator, The first input end of the comparator is connected with the D/A converter module, and the second input connects a sawtooth waveforms or triangular wave Signal, analog control signal and the sawtooth waveforms or triangular signal for being exported according to the D/A converter module are carried out Compare generation control signal, for adjusting the ON time of switching tube.
16. LED driver according to claim 13, it is characterised in that the input voltage in the integrator is and LED Load the voltage of a sampling resistor of electrical connection, the other end ground connection of the sampling resistor.
A kind of 17. LED drive chip, it is characterised in that including：

LED driver as any one of the integrator or claim 13 to 16 of any one of claim 1 to 6.
A kind of 18. LED device, it is characterised in that including：

LED load；

Rectifier bridge, the input of the rectifier bridge are electrically connected to an AC power, for being direct current by AC rectification；

First electric capacity, the both ends of first electric capacity are respectively electrically connected to two rectification branch roads in parallel in the rectifier bridge, use It is filtered in direct current；

Energy storage inductor, fly-wheel diode and the second electric capacity, after second electric capacity is in parallel with LED load with the afterflow two Pole pipe and energy storage inductor series connection, the other end of the energy storage inductor are coupled to a rectification branch road of the rectifier bridge；

Using the LED driver any one of claim 13 to 16, the LED load and the energy storage inductor are arranged at Between, for adjusting and stablizing the electric current of the LED load.
A kind of 19. LED device, it is characterised in that including：

LED load；

Ripple electric capacity is removed, is parallel to the LED load；

LED constant current drive device, with the LED load and it is described go ripple capacitance connection, for exporting a constant LED drivings Electric current；And

LED current ripple as any one of claim 7 to 11 eliminates circuit, located at the LED load and the LED Between constant current driving device.
20. a kind of LED current ripple removing method, it is characterised in that comprise the following steps：

The input voltage related to LED load is obtained, by the input voltage compared with a reference voltage and according to both Comparative result and export corresponding logical signal；

Counted based on the logical signal to generate digital controlled signal；

Digital-to-analogue conversion is carried out to the digital controlled signal to generate the gentle analog control signal that rises and falls；And

According to the analog control signal, voltage or the electric current of LED load are adjusted to cause the average current of the LED load to protect It is fixed to keep steady.
21. LED current ripple removing method according to claim 20, it is characterised in that by the input voltage and one Reference voltage is compared and included the step of exporting corresponding logical signal according to both comparative results：By the input Voltage exports the first logic letter when the input voltage is more than or equal to the reference voltage compared with a reference voltage Number, and export the second logical signal when the input voltage is less than the reference voltage；Carried out based on the logical signal The step of counting, includes carrying out first based on first logical signal counting and carry out the based on second logical signal Two count.
22. the LED current ripple removing method according to claim 20 or 21, it is characterised in that believed based on the logic The step of number being counted is included being carried out based on high level logic signal plus counting and subtracted based on low-level logic signal Count.
23. LED current ripple removing method according to claim 22, it is characterised in that in a power frequency period, institute The number stated plus counted is identical with the number for subtracting counting, and the incrementss and decrement of the digital controlled signal are equal.
24. LED current ripple removing method according to claim 20, it is characterised in that when being counted, be based on Count frequency using below equation generate：

F_CLK=K* | V_IN-V_REF|

Wherein, F_CLKFor count frequency, V_INFor input voltage, V_REFFor reference voltage, K is the coefficient of frequency modulation of voltage controlled oscillator.
25. LED current ripple removing method according to claim 20, it is characterised in that obtain related to LED load The step of input voltage, includes：Detect LED load negative terminal voltage, using the difference of the negative terminal voltage and a sampled voltage as Input voltage；Or the negative terminal voltage of LED load is detected, using the negative terminal voltage as input voltage.