CN104812121A - LED driving circuit - Google Patents
LED driving circuit Download PDFInfo
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- CN104812121A CN104812121A CN201410039919.1A CN201410039919A CN104812121A CN 104812121 A CN104812121 A CN 104812121A CN 201410039919 A CN201410039919 A CN 201410039919A CN 104812121 A CN104812121 A CN 104812121A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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- Circuit Arrangement For Electric Light Sources In General (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention relates to an LED driving circuit. The LED driving circuit comprises a switching power source which is used for receiving an external power source and generating adjusted output voltage according to adjustment signals, a linear power source circuit which is used for receiving the output voltage of the switching power source and converting the output voltage to linear voltage and providing the linear voltage to an LED muddle set, a ripple signal sampling circuit which is used for acquiring ripple signals generated by the linear power source circuit, a ripple signal compensation circuit which is used for receiving the acquired ripple signals and converting the same into compensation voltage signals, an output voltage adjustment circuit which is used for receiving voltage feedback signals of the linear power source circuit and the compensation voltage signals and generating adjustment signals according to a difference value between the voltage feedback signals and reference voltage so as to adjust the output voltage of the switching power source, wherein the reference voltage is equal to the sum of a preset first reference voltage source and the compensation voltage signals.
Description
Technical field
The present invention relates to the drive circuit for driving LED light source.
Background technology
LED is as a kind of novel illumination light source, and with its long-life, specular removal, how photochromic and once light-distribution directional illumination function, the many advantages such as can work under safe voltage, becomes the development trend of lighting source of new generation.
Traditional LED drive circuit is usually by Switching Power Supply (Switched-Mode Power Supply, SMPS) receive external ac power source input (or DC power supply input) and adjust the output voltage signal being provided to LED module, with the needs making it meet power supply according to adjustment signal such as pulse-width modulation (PWM) signal.
The simplest LED drive circuit only includes one-level Switching Power Supply, although this structure structure is simple, but the output voltage that one-level Switching Power Supply is supplied to LED module is not highly stable usually, the electric current on LED module can be affected, thus produce ripple current (Ripple Current), and then cause quality of lighting to decline and the useful life of LED module can be reduced.
More complicated LED drive circuit then comprises at least two-stage Switching Power Supply or comprise special constant current chip, by the adjustment of two-stage and the above Switching Power Supply of two-stage or constant current chip, final output voltage can be made to become more stable, because two-stage or the above Switching Power Supply of two-stage can carry out the adjustment of more than two-stage or two-stage to external power source, or special constant current chip also can carry out accurate adjustment to external power source.But, often increase a Switching Power Supply or often use a special constant current chip, all significantly will increase cost and the design complexities of LED drive circuit, be not suitable for being applied in common occasion.
So, need to provide a kind of new LED drive circuit to solve the problems referred to above.
Summary of the invention
Present conclusion one or more aspect of the present invention is so that basic comprehension of the present invention, and wherein this conclusion is not extensive overview of the present invention, and also not intended to be identifies some key element of the present invention, and also also not intended to be marks its scope.On the contrary, the main purpose of this conclusion presented concepts more of the present invention with reduced form before hereafter presenting more detailed description.
The invention reside in and a kind of LED drive circuit is provided, for driving LED module.This LED drive circuit comprises:
Switching Power Supply, for receiving external power source and producing the output voltage after adjustment according to adjustment signal;
Linear power source circuit, for receiving the output voltage of this Switching Power Supply, and is converted into linear voltage and is supplied to this LED module;
Ripple signal sample circuit, for gathering the ripple signal that this linear power source circuit produces;
Ripple signal compensating circuit, for receiving the ripple signal that this collects, and is converted into compensation voltage signal; And
Output voltage regulation circuit, for receiving voltage feedback signal and this compensation voltage signal of this linear power source circuit, and produce the output voltage of this adjustment signal to this Switching Power Supply according to the difference between this voltage feedback signal and reference voltage and regulate, wherein this reference voltage equals default first reference voltage source and this compensation voltage signal sum.
Compared to prior art, the output voltage regulation circuit provided in LED drive circuit of the present invention makes to carry out comprehensively Switching Power Supply according to comprehensive feedback and collection signal and control accurately.On the one hand, this output voltage regulation circuit receives the voltage feedback signal from linear power source circuit, the output voltage can being monitored this Switching Power Supply by this voltage feedback signal in real time meets desired value, namely compare with the first reference voltage source, then result produces the output voltage that corresponding adjustment signal adjusts this Switching Power Supply based on the comparison, on the other hand, this output voltage regulation circuit also gathers the ripple signal from linear power source circuit further by this ripple signal sample circuit, and obtain by this ripple signal compensating circuit the signal energy being in the ripple signal of this sampling and having in the time period of ripple current, and be translated into this compensation voltage signal, comparing with the voltage feedback signal from linear power source circuit after itself and this first reference voltage source is combined, the adjustment signal of generation is so made not only to make this Switching Power Supply meet desired value, and this LED module can be made normally to work under lowest power, and then reduce the loss of power.In addition, because LED drive circuit of the present invention only applies one-level Switching Power Supply, and do not apply secondary or multi-stage switching power supply or special constant current chip, therefore greatly reduce cost yet.
Accompanying drawing explanation
Be described for embodiments of the present invention in conjunction with the drawings, the present invention may be better understood, in the accompanying drawings:
Fig. 1 is the schematic block diagram of a kind of better embodiment of LED drive circuit of the present invention.
Fig. 2 illustrates a kind of better circuit diagram executing mode of current rectifying and wave filtering circuit in Fig. 1 and linear power source circuit.
Fig. 3 illustrates a kind of better circuit diagram executing mode of the output voltage regulation circuit in Fig. 1.
Fig. 4 illustrates a kind of better circuit diagram executing mode of the ripple signal sample circuit in Fig. 1.
Fig. 5 illustrates the graph of a relation between ripple current, ripple voltage and shaping voltage.
Fig. 6 illustrates a kind of better circuit diagram executing mode of the ripple voltage Shaping Module in Fig. 4.
Fig. 7 illustrates a kind of better circuit diagram executing mode of the ripple signal compensating circuit in Fig. 1.
Embodiment
Below will describe the specific embodiment of the present invention, and it is pointed out that in the specific descriptions process of these execution modes, in order to carry out brief and concise description, this specification can not all do detailed description to all features of the execution mode of reality.Should be understandable that; in the actual implementation process of any one execution mode; as in the process of any one engineering project or design object; in order to realize the objectives of developer; in order to meet that system is correlated with or that business is relevant restriction; usually can make various concrete decision-making, and this also can change to another kind of execution mode from a kind of execution mode.In addition, it will also be appreciated that, although effort done in this development process may be complicated and tediously long, but for those of ordinary skill in the art relevant to content disclosed by the invention, some designs that the basis of the technology contents of disclosure exposure is carried out, manufacture or production etc. changes just conventional technological means, not should be understood to content of the present disclosure insufficient.
Unless otherwise defined, the technical term used in claims and specification or scientific terminology should be in the technical field of the invention the ordinary meaning that the personage with general technical ability understands." first ", " second " that use in patent application specification of the present invention and claims and similar word do not represent any order, quantity or importance, and are only used to distinguish different parts.The similar word such as " one " or " one " does not represent restricted number, but represents to there is at least one." comprise " or the similar word such as " comprising " mean to appear at " comprising " or " comprising " before element or object contain the element or object and equivalent element thereof that appear at " comprising " or " comprising " presented hereinafter, do not get rid of other elements or object." connection " or " being connected " etc. similar word be not defined in physics or the connection of machinery, no matter but can comprise electric connection, be direct or indirectly.
Please refer to Fig. 1, is the schematic block diagram of a kind of better embodiment of LED drive circuit 100 of the present invention.This LED drive circuit 100 comprises external power source input interface 110, current rectifying and wave filtering circuit 120, Switching Power Supply (Switched-Mode Power Supply, SMPS) 130, linear power source circuit 140, LED module 150, output voltage regulation circuit 160, ripple signal sample circuit 170 and ripple signal compensating circuit 180.Wherein, this LED module 150 can be the part of this LED drive circuit 100, also can be respective independently part, be incorporated this LED drive circuit part for convenience of description.
This external power source input interface 110 for receiving external power source signal (not shown), as 220V AC power or 24V DC power supply etc.Here only illustrate, in fact external power source signal can adjust as required, provides and stablize suitable output voltage to the LED module 150 of its inside after a series of controls of this external power source signal by this LED drive circuit 100 subsequent conditioning circuit.This LED module 150 may comprise single LED element, also may comprise the combination of several LED element, and the type of LED element is also not limited to, and all can adjust according to actual needs a certain.
This current rectifying and wave filtering circuit 120 for carrying out rectification and/or filtering process to external power source, to obtain the input voltage required for Switching Power Supply 130.Due to the technology that current rectifying and wave filtering circuit is more ripe, therefore the present invention only gives the schematic rectification execution mode of Fig. 2 is illustrated as an example.According to actual needs, the position of this current rectifying and wave filtering circuit 120 also can adjust accordingly, such as except the example of Fig. 1 signal, this current rectifying and wave filtering circuit 120 can also be arranged on the rear end of this Switching Power Supply 130, to carry out rectification and/or filtering process to the output voltage signal of Switching Power Supply 130.Or the rectifying part of this current rectifying and wave filtering circuit 120 is arranged at the front end of this Switching Power Supply 130, the filtering part of this current rectifying and wave filtering circuit 120 is then arranged at the rear end of this Switching Power Supply 130.Again or, the filtering part of this current rectifying and wave filtering circuit 120 is arranged at the front end of this Switching Power Supply 130, the rectifying part of this current rectifying and wave filtering circuit 120 is then arranged at the rear end of this Switching Power Supply 130.Above-mentionedly schematically illustrate some execution modes, specifically also can carry out the adjustment of other types according to actual needs, be not limited to the above-mentioned example provided.Except arrangement or filtering process, needs according to side circuit also can carry out other suitable process to the signal in circuit, such as amplify process etc., due to these signal transacting not designing points of the present invention, therefore do not illustrate here, and also do not illustrate out in figure, but according to the understanding of those skilled in the art, corresponding signal transacting can be made.
This Switching Power Supply 130 arranges filtered external power source signal for receiving this external power source signal or passing through, and adjust its output voltage 132 according to the adjustment signal 162 from output voltage regulation circuit 160, such as, this adjustment signal 162 can be the direct current signal that an amplitude changes up and down with feedback signal.It is appreciated that, as an example, this Switching Power Supply 130 inside generally includes PWM and adjusts signal controlling integrated circuit and the transistor (not shown) as switch element, this PWM adjusts signal controlling integrated circuit produces duty ratio corresponding pwm signal according to this adjustment signal 162, and then control the break-make of this switch element, thus the output voltage 132 of corresponding this Switching Power Supply 130 of adjustment.This PWM adjusts signal controlling integrated circuit and is usually connected with this output voltage regulation circuit 160, as optical coupling input interface by external interface.This output voltage regulation circuit 160 inputs this adjustment signal 162 by above-mentioned external interface and adjusts signal controlling integrated circuit to this PWM.Concrete structure due to this Switching Power Supply 130 inside is not invention main points of the present invention, therefore does not elaborate here.
This linear power supply (Linear Source) circuit 140, for receiving the output voltage 132 of this Switching Power Supply 130 and being converted to stable linear voltage 142 and being supplied to this LED module 150, normally works to make it.Because this linear power source circuit 140 is more ripe technology, therefore the present invention only provides the schematic linear power supply execution mode of Fig. 2 is illustrated as an example, also the linear power source circuit of other types or linear power supply chip can be selected in other execution modes to realize providing the function of regulated linear voltage, be not limited to the execution mode that Fig. 2 provides, will not enumerate here.
This output voltage regulation circuit 160 is for receiving the voltage feedback signal 144 of this linear power source circuit 140, this voltage feedback signal 144 indirectly (or directly) reflects the change of the output voltage 132 of this Switching Power Supply 130, and this change may be caused by reasons such as the change of external power source or Switching Power Supplies 130 self.When the output voltage 132 of this Switching Power Supply 130 changes, the linear voltage 142 that this linear power source circuit 140 exports LED module 150 to may also change thereupon, namely occurs spread of voltage situation, this instability that LED module 150 may be caused to work.For this reason, this output voltage regulation circuit 160 is according to the voltage feedback signal 144 received and reference voltage (the reference voltage source V as shown in Figure 3 preset
ref1) comparative result produce and adjust signal (i.e. PWM adjustment signal 162) accordingly and be given to this Switching Power Supply 130, signal controlling integrated circuit is adjusted with the PWM controlled in this Switching Power Supply 130, this PWM adjusts signal controlling integrated circuit and adjusts according to this adjustment signal 162 duty ratio that PWM adjusts signal, and then adjustment output voltage 132, be adjusted in satisfactory scope with the linear voltage 142 making this linear power source circuit 140 export, thus ensure that this LED module 150 can normally work.Composition graphs 3 is provided the concrete better embodiment of of this output voltage regulation circuit 160 by subsequent paragraph, to describe its concrete operation principle in detail.
But the reference voltage of reference is changeless in above-mentioned output voltage regulation circuit 160, therefore the reference voltage sometimes only preset according to this can not adjust output voltage 132 completely and reaches satisfactory optimum range.Such as, in order to effectively eliminate the ripple flowing through electric current on LED module 150, need the pressure drop of linear power source circuit 140 neutral line power supply to be set with larger surplus, with the error of the energy hunting or output voltage 132 of tackling external power input.Therefore, by means of only the reference voltage V that this is preset
ref1output voltage 132 after adjustment may make electric energy loss become higher, because do not compensate the ripple signal that linear power source circuit 140 produces.Therefore LED drive circuit 100 of the present invention additionally provides ripple signal sample circuit 170 and ripple signal compensating circuit 180 further.
This ripple signal sample circuit 170 is for carrying out real-time sampling when this linear power source circuit 142 produces ripple signal 146 to it, and the ripple signal 173 after this sampling exports to this ripple signal compensating circuit 180.This ripple signal compensating circuit 180 compensates control to the ripple signal (or the ripple signal after shaping) after this sampling, and exports compensation voltage signal 182 and be given to this output voltage regulation circuit 160.This output voltage regulation circuit 160 after combining with this compensation voltage signal 182 according to the preset reference voltage in it more corresponding generation adjust signal 162, the linear voltage 142 that this linear power source circuit 140 is exported is adjusted in satisfactory scope by the adjustment signal 162 after this combination adjustment and the power consumed is minimum.Composition graphs 4-Fig. 7 is provided the concrete better embodiment of this ripple signal sample circuit 170 and ripple signal compensating circuit 180 by subsequent paragraph, to describe its concrete operation principle in detail.
Above-mentioned paragraph teaches the operation principle of LED drive circuit 100 entirety of the present invention, introduces circuit structure and the operation principle of various piece example below in conjunction with Fig. 2-Fig. 7 and embodiment respectively.It should be noted that, some execution modes that these execution modes are only used to facilitate the operation principle of the respective circuit of explanation and enumerate, and the adjusted design that these execution modes can carry out routinely according to the knowledge of persons skilled in the art, be not limited to example given here.
Please refer to Fig. 2, illustrate a kind of better circuit diagram executing mode of current rectifying and wave filtering circuit 120 and linear power source circuit 140 in Fig. 1.Just as described above, Fig. 2 simply show a schematic execution mode, and in other execution modes, this current rectifying and wave filtering circuit 120 and linear power source circuit 140 can need according to difference the circuit structure being designed to other.
In the execution mode of Fig. 2, this current rectifying and wave filtering circuit 120 comprises a bridge rectifier be made up of four diode D1-D4, namely the anode of this diode D1 and the negative electrode of this diode D3 are connected to a lead-out terminal of this external power source input interface 110, the anode of this diode D2 and the negative electrode of this diode D4 are connected to another lead-out terminal of this external power source input interface 110, the negative electrode of this diode D1 and the anode of this diode D3 are connected to an input terminal of this Switching Power Supply 130, the negative electrode of this diode D2 and the anode of this diode D4 are connected to another input terminal of this Switching Power Supply 130.Because this bridge rectifier is existing common technique, therefore no longer describe its operation principle in detail here.In present embodiment, do not comprise filter circuit part in this current rectifying and wave filtering circuit 120, this is due in some application, can satisfy the demand without the need to filtering.In other embodiments, suitable filter circuit can be increased accordingly as required, as capacitor filter.Because filter circuit is also existing common technique, therefore, do not provide corresponding example and diagram here for the purpose of simplifying the description.
In the execution mode of Fig. 2, this linear power source circuit 140 comprises a controllable accurate source of stable pressure device TL
1(if model is TL431), three resistance R
1-R
3, a filter capacitor C
1and electronic switch (as a metal-oxide-semiconductor) Q
1.
Two voltage output ends of this Switching Power Supply 130 and this two resistance R
1and R
2series connection, to carry out voltage division processing to the output voltage of this Switching Power Supply 130.This resistance R
2two ends respectively with this controllable accurate source of stable pressure device TL
1negative electrode and positive electrode connect, this resistance R
2the voltage distribution at two ends meets this controllable accurate source of stable pressure device TL
1the voltage request at negative electrode and positive electrode two ends, specifically sets according to actual parameter.This electric capacity C
1with this electronic switch Q
1and this resistance R
3with this resistance R after composition series circuit
1and R
2the series circuit of composition is connected in parallel.This electronic switch Q
1control end be connected to this resistance R
1with R
2between node D on, this controllable accurate source of stable pressure device TL
1reference pole be connected to this electronic switch Q
1with this resistance R
3between node C on.This electric capacity C
1two-end-point A and B be connected to two power inputs of this LED module 150 respectively.
During work, this Switching Power Supply 130 provides this output voltage V
a(i.e. Fig. 1 signal 132) is given to this linear power source circuit 140, as 24V direct voltage.According to this controllable accurate source of stable pressure device TL
1device function, it is given on this node C with reference to pole by exporting fixing voltage, to make voltage clamping on this node C in this fixing voltage, as being clamped to 1.25V.As C point voltage V
cduring >1.25V, due to this electronic switch Q
1be operated in amplification region, the voltage V of D point
dcan decline, and then the voltage V between B point and C point
bCcan rise.Due to V
c=V
a-V
aB-V
bC, therefore V
bCafter rising, the voltage V of C point
ccan decline until this clamp voltage is as 1.25V.Through above-mentioned a series of control, this electric capacity C
1two ends by output linearity voltage V
aB(i.e. Fig. 1 signal 142) is given to this LED module 150.In other execution modes, the linear power source circuit also by other circuit structures provides linear voltage to be given to this LED module 150, specifically requires to select according to actual design, illustrates no longer one by one here.
Meanwhile, in present embodiment, the voltage V of this B point
bthis output voltage regulation circuit 160 is exported to as this voltage feedback signal 144.Why this voltage feedback signal 144 can as the output voltage V of this Switching Power Supply 130 of reflection
a, be due to V
b=V
a-V
aB, therefore V
bindirectly reflect the output voltage V of this Switching Power Supply 130
a.In other execution modes, also can directly by the output voltage V of this Switching Power Supply
aexport to this output voltage regulation circuit 160 as this voltage feedback signal 144, or the voltage signal other be associated is as this voltage feedback signal 144, and is not limited to a certain feedback system.
Please continue to refer to Fig. 3, illustrate a kind of better circuit diagram executing mode of the output voltage regulation circuit 160 in Fig. 1.In present embodiment, this output voltage regulation circuit 160 comprises a comparator U
1, a reference voltage source V
ref1and an electric capacity C
2.
This comparator U
1inverting input receive this linear power source circuit 140 export this voltage feedback signal 144, this comparator U
1normal phase input end receive this reference voltage source V
ref1, this electric capacity C
2be connected to this comparator U
1inverting input and output between, this comparator U
1output produce this adjustment signal 162.This reference voltage source V
ref1according to this Switching Power Supply 130 actual needs produce output voltage and set, i.e. this reference voltage source V
ref1value to Switching Power Supply 130 output voltage that produces should be expected, namely direct to should the desired value of voltage feedback signal 144.
During work, when this voltage feedback signal 144 is less than this reference voltage source V
ref1time, show that the output voltage 132 that this Switching Power Supply 130 produces is less than desired value, so time this adjustment signal 162 by output one on the occasion of adjustment signal 162 improve the duty ratio that PWM in Switching Power Supply 130 adjusts signal, and then the output voltage 132 improving this Switching Power Supply 130 is to make it equal or to level off to desired value.Otherwise, when this voltage feedback signal 144 is greater than this reference voltage source V
ref1time, show that the output voltage 132 that this Switching Power Supply 130 produces is larger than desired value, so time this adjustment signal 162 the adjustment signal 162 of an output negative value is reduced the duty ratio that PWM in Switching Power Supply 130 adjusts signal, and then the output voltage 132 reducing this Switching Power Supply 130 is to make it equal or to level off to desired value.Therefore, by the feedback adjusting of this output voltage regulation circuit 160, the output voltage 132 that this Switching Power Supply 130 can be made to produce equals all the time or levels off to desired value.In other embodiments, this output voltage regulation circuit 160 also can be designed to the circuit form of other structures, such as, realize this voltage feedback signal 144 and this reference voltage source V by Application comparison chip
ref1comparison, and export corresponding adjustment signal 162, differing here one illustrates.
Please continue to refer to Fig. 4, illustrate a kind of better circuit diagram executing mode of the ripple signal sample circuit 170 in Fig. 1.In present embodiment, this ripple signal sample circuit 170 comprises ripple voltage Shaping Module 172 and shaping voltage output module 174.In some embodiments, also only can apply this ripple voltage Shaping Module 172 and omit this shaping voltage output module 174.
In this embodiment, this ripple signal sample circuit 170 is the voltage V according to B point in Fig. 2
bsampling source as this ripple signal 146 carries out sampling, and namely the sampling source of this ripple signal 146 and the feedback sources of above-mentioned voltage feedback signal 144 are same signal source.In other execution modes, also other different sampled points can be selected to carry out sampling or feedback capture, as long as the feedback signal that the signal and the actual needs that meet feedback sources or sampling source place obtain or sampled signal are directly or indirectly associated, be not limited to a certain feedback or sample mode.
For the ripple voltage Shaping Module 172 in present embodiment, it comprises a comparator U
2and a reference voltage source V
ref2.In this embodiment, this ripple voltage Shaping Module 172 is for converting this ripple signal 146 to square-wave signal, so that the follow-up process to signal, other execution mode is also convertible into the signal of other types or does not carry out shaping conversion.
In this embodiment, this comparator U
2inverting input for receiving this ripple signal 146, this comparator U
2normal phase input end for receiving this reference voltage source V
ref2.With reference to figure 5, illustrate the graph of a relation between ripple current 52, ripple voltage 54 and shaping voltage 56.Wherein, this ripple current 52, for flowing through the partial waveform figure of current signal when producing ripple current of this LED module 150, can be found out, at time period T1-T2, when T3-T4, T5-T6, ripple-free electric current produces, and create ripple current when time period T2-T3, T4-T5, T6-T7.Because Direct Sampling current signal 52 may have the problem of energy loss, therefore that present embodiment Direct Sampling is B point place voltage signal V in ripple voltage signal 54(associated with it and linear power source circuit 140
b).As can be seen from Figure 5, at the time period T1-T2 that ripple-free electric current produces, in T3-T4, T5-T6, the amplitude of this ripple voltage 54 be on the occasion of, and producing the time period T2-T3 of ripple current, in T4-T5, T6-T7, the amplitude of this ripple voltage 54 is equal to zero.Therefore, by this comparator U
2shaping, can by the amplitude of this ripple voltage 54 on the occasion of time period equal shaping equal zero, and null for the amplitude of this ripple voltage 54 time period equal shaping is equaled a fixed voltage value, namely as the square-wave signal (1731 of corresponding diagram 4) of shaping voltage 56.Therefore, relatively ripple current 52 and shaping voltage 56, there is the time period T2-T3 of ripple in this ripple current 52 known, T4-T5, T6-T7 is to should amplitude time period of shaping voltage 56, and there is not the time period T1-T2 of ripple, T3-T4, T5-T6 are to should low amplitude value time period of shaping voltage 56.
In other embodiments, this ripple voltage Shaping Module 172 also realizes by the shaping circuit of other types.The such as another kind of execution mode of Fig. 6 signal.In this execution mode, this ripple voltage Shaping Module 172 comprises resistance R
6and electronic switch Q
4(as triode).This resistance R
6with this electronic switch Q
4be series at a voltage source V
ccand between ground, this electronic switch Q
4control end for receiving this ripple signal 146, this resistance R
6with electronic switch Q
4node be used for be similar to 56 in Fig. 5 as shaping voltage 1731() output.Yi Zhi, when this ripple signal 146(is similar to 54 in Fig. 5) on the occasion of time, this electronic switch Q
4conducting, therefore this shaping voltage 1731 equals zero, when this ripple signal 146 is zero, this electronic switch Q
4cut-off, therefore this shaping voltage 1731 equals a fixed voltage value.This ripple voltage Shaping Module 172 is also by other circuit realiration, and differing here one illustrates.
Be back to Fig. 4, this ripple signal sample circuit 170 comprises a shaping voltage output module 174 further, and in this embodiment, this shaping voltage output module 174 is an image current source circuit, and it typically comprises two resistance R
4and R
5, triode Q
2and Q
3, resistance R
4with triode Q
2the side of composition image current source circuit, resistance R
5with Q
3the opposite side of composition image current source circuit, by the output function of this image current source circuit 174, the amplitude part of the shaping square-wave voltage 1731 that this ripple voltage Shaping Module 172 can be made to produce is stable again after producing image current 1732 exports to this ripple signal compensating circuit 180.Because image current source circuit is existing circuit common, therefore do not illustrate here.As described above, in other embodiments, also can omit this shaping voltage output module 174 part, and directly the shaping voltage 1731 that this ripple voltage Shaping Module 172 produces be exported to this ripple signal compensating circuit 180.In other execution modes, the voltage that the voltage follower circuit that this shaping voltage output module 174 also can be designed to other types carrys out this shaping voltage 1731 amplitude part of stable acquisition exports.
Please continue to refer to Fig. 7, illustrate a kind of better circuit diagram executing mode of the ripple signal compensating circuit 180 in Fig. 1.In this embodiment, this ripple signal compensating circuit 180 comprises resistance R
7, resistance R
8, diode D
5and storage capacitor C
3.
This diode D
5anode by resistance R
7be connected to this ripple signal sample circuit 170, to receive the ripple signal 173(signal 1731 or 1732 as shown in Figure 4 after its sampling produced).This diode D
5negative electrode to connect this storage capacitor C
3rear ground connection.This diode D
5with this storage capacitor C
3between node by resistance R
8be connected to this output voltage regulation circuit 160, with the voltage signal V afforded redress to it
add(collective reference Fig. 3, i.e. 182 in Fig. 1).This resistance R in this ripple signal compensating circuit 180
7, R
8and diode D
5are all the performances in order to regulate accumulator, as resistance plays the effect of current limliting, diode plays the effect preventing current reflux.In other execution modes, this storage capacitor C
3the energy-storage travelling wave tube that can have energy-storage function by other is replaced, and this resistance R
7, R
8and diode D
5all can be replaced by the electronic component of other similar functions, circuit structure also can adjust as required, is not limited to the example that present embodiment provides.
During work, when linear power source circuit 140 produces ripple current, such as, time period T2-T3 shown in Fig. 5, T4-T5, T6-T7, correspondence is produced reshaping signal 173 by this ripple signal sample circuit 170, square-wave signal 56 as shown in Figure 5.Accordingly, at the forward time period T2-T3 of this square-wave signal 56, in T4-T5, T6-T7, this ripple signal sample circuit 170 is by the storage capacitor C in this ripple signal compensating circuit 180
3charge, its both end voltage is increased.And then the voltage V of this increase
ddwill comparator U in the output voltage regulation circuit 160 shown in compensation image 3
1the voltage reference value V of normal phase input end
ref1, so can improve the scope of the reference voltage (buffer voltagc) compared with the feedback voltage signal 142 of this linear power source circuit 140, effectively to eliminate the ripple current in this linear power source circuit 140.In addition, again due to storage capacitor C in this ripple signal compensating circuit 180
3electric energy increment correspond to ripple current in this linear power source circuit 140, the voltage V of therefore this increase
addjust can eliminate the ripple current in linear power source circuit 140, this LED module 150 can be made normally to work under lowest power, thus reduce the loss of power.So, by the control of foregoing circuit, LED drive circuit 100 of the present invention can carry out work by normal control LED module 150 under lowest power.In addition, because LED drive circuit 100 of the present invention only applies one-level Switching Power Supply, and do not apply secondary or multi-stage switching power supply or special constant current chip, therefore greatly reduce cost yet.
Although describe the present invention in conjunction with specific execution mode, those skilled in the art will appreciate that and can make many amendments and modification to the present invention.Therefore, recognize, the intention of claims is to cover all such modifications in true spirit of the present invention and scope and modification.
Claims (10)
1. a LED drive circuit, for driving LED module, is characterized in that: this LED drive circuit comprises:
Switching Power Supply, for receiving external power source and producing the output voltage after adjustment according to adjustment signal;
Linear power source circuit, for receiving the output voltage of this Switching Power Supply, and is converted into linear voltage and is supplied to this LED module;
Ripple signal sample circuit, for gathering the ripple signal that this linear power source circuit produces;
Ripple signal compensating circuit, for receiving the ripple signal that this collects, and is converted into compensation voltage signal; And
Output voltage regulation circuit, for receiving voltage feedback signal and this compensation voltage signal of this linear power source circuit, and produce the output voltage of this adjustment signal to this Switching Power Supply according to the difference between this voltage feedback signal and reference voltage and regulate, wherein this reference voltage equals default first reference voltage source and this compensation voltage signal sum.
2. LED drive circuit as claimed in claim 1, the ripple signal of wherein this ripple signal sample circuit collection is the ripple voltage signal corresponding with ripple current.
3. LED drive circuit as claimed in claim 2, wherein this ripple signal sample circuit comprises a comparator and default second reference voltage source, the inverting input of this comparator receives this ripple voltage signal, the normal phase input end of this comparator receives this second reference voltage source, ripple signal after the output output Shaping of this comparator, the ripple signal after this shaping is square-wave signal and the amplitude part of this square-wave signal corresponding time period occurring ripple current.
4. LED drive circuit as claimed in claim 2, wherein this ripple signal sample circuit comprises a resistance and a switch element, this resistance and this switch elements in series are at one between voltage source and ground, the control end of this switch element receives this ripple voltage signal, ripple signal after node output Shaping between this resistance and this switch element, the ripple signal after this shaping is square-wave signal and the amplitude part of this square-wave signal corresponding time period occurring ripple current.
5. the LED drive circuit as described in claim 3 or 4, wherein this ripple signal sample circuit comprises an image current source circuit further, and the energy for the amplitude part by this square-wave signal exports in the form of electric current.
6. as the LED drive circuit in claim 1-4 as described in any one, wherein this ripple signal compensating circuit comprises an energy-storage travelling wave tube, the voltage signal that this energy-storage travelling wave tube has in the time period of ripple current in correspondence based on this ripple signal collected carries out energy storage, and is this compensation voltage signal by the Conversion of Energy of this storage.
7. LED drive circuit as claimed in claim 6, wherein this energy-storage travelling wave tube comprises electric capacity.
8. LED drive circuit as claimed in claim 7, wherein this ripple signal compensating circuit also comprises the first resistance, the second resistance and diode, the anode of this diode receives this ripple signal collected by this first resistance, the negative electrode of this diode is by this capacity earth, and the node of this diode and electric capacity provides this compensation voltage signal by this second resistance.
9. LED drive circuit as claimed in claim 1, wherein this output voltage regulation circuit comprises a comparator and an electric capacity, the inverting input of this comparator receives the voltage feedback signal of this linear power source circuit output, the normal phase input end of this comparator receives this reference voltage, this electric capacity is connected between the inverting input of this comparator and output, and the output of this comparator produces this adjustment signal.
10. LED drive circuit as claimed in claim 1, wherein this linear power source circuit comprises a controllable accurate source of stable pressure device, first to the 3rd resistance, an electric capacity and an electronic switch, two voltage output ends of this Switching Power Supply and this first and second resistant series, the two ends of this second resistance are connected with the negative electrode and positive electrode of this controllable accurate source of stable pressure device respectively, the series circuit formed with this first and second resistance after this electric capacity becomes series circuit with this electronic switch and the 3rd resistor group is connected in parallel, the control end of this electronic switch is connected on the node between this first resistance and second resistance, the reference pole of this controllable accurate source of stable pressure device is connected on the node between this electronic switch and the 3rd resistance, the two ends of this electric capacity are connected to two power inputs of this LED module respectively.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410039919.1A CN104812121B (en) | 2014-01-27 | 2014-01-27 | Led drive circuit |
| PCT/CN2015/070992 WO2015109977A1 (en) | 2014-01-27 | 2015-01-19 | Led drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410039919.1A CN104812121B (en) | 2014-01-27 | 2014-01-27 | Led drive circuit |
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| Publication Number | Publication Date |
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| CN104812121A true CN104812121A (en) | 2015-07-29 |
| CN104812121B CN104812121B (en) | 2018-07-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410039919.1A Expired - Fee Related CN104812121B (en) | 2014-01-27 | 2014-01-27 | Led drive circuit |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN104812121B (en) |
| WO (1) | WO2015109977A1 (en) |
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| CN105188201A (en) * | 2015-08-25 | 2015-12-23 | 北京极澈远技术有限公司 | High-speed light modulation circuit applied to LED illumination |
| CN106527561A (en) * | 2017-01-04 | 2017-03-22 | 西南应用磁学研究所 | Efficient magnetic tuning device drive circuit with voltage tracking function |
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| CN108811225A (en) * | 2017-05-04 | 2018-11-13 | 深圳市帝莱特照明有限公司 | A kind of middle low power intelligent lighting dims color-changed LED driving power without stroboscopic |
| CN112423434A (en) * | 2020-11-13 | 2021-02-26 | 浙江大学 | Power supply ripple based multi-path LED lamp brightness bypass detection device and method |
| CN112912814A (en) * | 2018-10-31 | 2021-06-04 | 罗姆股份有限公司 | Linear power supply circuit |
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| CN112953220B (en) * | 2021-02-03 | 2022-12-30 | 电子科技大学 | DC-DC converter with current sensing and control |
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| CN112912814B (en) * | 2018-10-31 | 2023-01-03 | 罗姆股份有限公司 | Linear power supply circuit |
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| CN112423434B (en) * | 2020-11-13 | 2021-10-08 | 浙江大学 | Power supply ripple based multi-path LED lamp brightness bypass detection device and method |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2015109977A1 (en) | 2015-07-30 |
| CN104812121B (en) | 2018-07-06 |
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