CN103037597A - Multi-channel LED (Light Emitting Diode) constant current control circuit and LED light source control system - Google Patents
Multi-channel LED (Light Emitting Diode) constant current control circuit and LED light source control system Download PDFInfo
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Abstract
The invention discloses a multi-channel LED (Light Emitting Diode) constant current control circuit, which comprises a power supply module, a booster module, a DC/DC (Direct Current/Direct Current) control module, an LED string module, a constant current adjusting module and a feedback control module, wherein an input end of the booster module is connected with the power supply module; an output end of the booster module is connected with an input end of the constant current adjusting module through the LED string module; the feedback control module is connected with a feedback input end of the DC/DC control module and respectively connected with an output end and a control end of the constant current adjusting module; and a driving output end of the DC/DC control module is connected with a control end of the booster module. The invention further discloses an LED light source control system, which comprises the multi-channel LED constant current control circuit. The multi-channel LED constant current control circuit disclosed by the invention has the advantage as follows: the constant current control precision is high; through adjustment of the current of each LED string, the currents of the LED strings are equal to each other, so that the illumination brightnesses of the LED strings are equal to each other; the uniformity of the LED illumination brightnesses is enhanced; and the multi-channel LED constant current control circuit is suitable for any electronic system using constant current control.
Description
Technical field
The present invention relates to the technical field of integrated circuit (IC) design, relate in particular to a kind of multipath LED constant current control circuit and led light source control system.
Background technology
LED is widely used in illumination, demonstration backlight field as a kind of green light source of low-power consumption.By the voltage-current characteristic of LED as can be known, LED electric current and voltage are exponential relationship, and small change in voltage can cause very large curent change, and electric current directly determines the luminosity of LED, so stable for the brightness preservation that makes LED, must adopt constant current mode, rather than constant voltage mode.
In the prior art, when the LED number is less, usually adopt the mode of series connection, as shown in Figure 1, the electric current that flows through each LED equates, so brightness is consistent.The advantage of this structure is simple in structure, and shortcoming is to be applicable to the less application of LED number.
When the LED number is more, need to adopt series-parallel mode, so just form the topological structure of multi-string LED parallel connection, this structure is applicable to the more application of LED number.The mode of current sample has two kinds usually: first kind of way as shown in Figure 2, the electric current of sampling a certain LED string wherein only, the current constant of the LED string that can guarantee like this to sample, but the electric current between each LED string is variant unavoidably, so caused the inconsistent phenomenon of brightness between each LED string; The second way as shown in Figure 3, the electric current of sampling is the electric current sum of all LED strings, this structure can guarantee that the electric current sum of all LED strings keeps constant, but can not solve the current difference problem between the LED string.
Summary of the invention
Main purpose of the present invention is to propose a kind of multipath LED constant current control circuit and led light source control system, is intended to by regulating the electric current of every paths of LEDs string, so that the electric current of every paths of LEDs string is equal, realizes that the luminosity of every paths of LEDs string equates.
In order to achieve the above object, the present invention proposes a kind of multipath LED constant current control circuit, the boost module that this multipath LED constant current control circuit comprises supply module, be used for input voltage is boosted, be used for controlling described boost module boost DC/DC control module and the LED string module of ratio, described LED string module comprises at least two paths of LED string, and this multipath LED constant current control circuit also comprises for the constant current adjusting module of the electric current of adjusting the described LED string in each road and is used for controlling the feedback control module that described constant current adjusting module is adjusted electric current; Wherein:
The input of described boost module is connected with described supply module, output is connected with the input of described LED string module, the output of described LED string module is connected with the input of described constant current adjusting module, the output of described constant current adjusting module is connected with the input of described feedback control module, the output of described feedback control module is connected with the feedback input end of described DC/DC control module respectively and is connected the control end of constant current adjusting module and connects, and the drive output of described DC/DC control module is connected with the control end of described boost module.
Preferably, described boost module comprises inductance, diode, electric capacity and switching tube; One end of described inductance is connected with described supply module as the input of described boost module, the other end of described inductance and the anodic bonding of described diode, and be connected with the drain electrode of described switching tube; The grid of described switching tube is connected with the output of described DC/DC control module, the source ground of described switching tube; The negative electrode of described diode is through described capacity earth, and is connected with the input of the described LED string in each road respectively.
Preferably, described switching tube is the NMOS pipe.
Preferably, described DC/DC control module comprises DC/DC accessory power supply and DC/DC control chip, the positive pole of described DC/DC accessory power supply is connected with the power end of described DC/DC control chip, and the negative pole of described DC/DC accessory power supply is connected with the earth terminal of described DC/DC control chip.
Preferably, described DC/DC control chip comprises reference power supply, error amplifier, comparator and driver element; The positive pole of described reference power supply is connected with the in-phase input end of described error amplifier, the minus earth of described reference power supply; The output of described error amplifier is connected with the inverting input of described comparator; The in-phase input end of described comparator is connected with the sawtooth waveforms input, and the output of described comparator is connected with the input of described driver element; The output of described driver element is connected with the grid of described switching tube as the output of described DC/DC control module.
Preferably, the described LED string in each road comprises some series connection and the identical LED of conducting direction, and the anode tap of the described LED string in each road all is connected with the negative electrode of described diode.
Preferably, described constant current adjusting module comprises at least two the constant current adjustment units corresponding with described LED string, and the input of each described constant current adjustment unit is connected with the cathode terminal of a described LED string.
Preferably, each described constant current adjustment unit comprises adjustment pipe, sampling resistor, operational amplifier and two-way selector; Wherein:
The drain electrode of described adjustment pipe is as the input of described constant current adjustment unit, connect with the cathode terminal of corresponding one described LED string, the source electrode of described adjustment pipe is through described sampling resistor ground connection, and respectively with the inverting input of described operational amplifier be connected an input pin of feedback control module and be connected, the grid of described adjustment pipe is connected with the output of described operational amplifier; The in-phase input end of described operational amplifier is connected with the output of described two-way selector; The first input end of described two-way selector is connected with an output pin of described feedback control module, and be connected with the inverting input of described error amplifier, the second input of described two-way selector is connected with the positive pole of described reference power supply, and the control end of described two-way selector is connected with another output pin of described feedback control module.
Preferably, described adjustment pipe is the NMOS pipe.
The present invention also proposes a kind of led light source control system, this led light source control system comprises the multipath LED constant current control circuit, this multipath LED constant current control circuit comprises supply module, for the boost module that input voltage is boosted, be used for controlling described boost module boost DC/DC control module and the LED string module of ratio, described LED string module comprises at least two paths of LED string, and this multipath LED constant current control circuit also comprises for the constant current adjusting module of the electric current of adjusting the described LED string in each road and is used for controlling the feedback control module that described constant current adjusting module is adjusted electric current; Wherein:
The input of described boost module is connected with described supply module, output is connected with the input of described LED string module, the output of described LED string module is connected with the input of described constant current adjusting module, the output of described constant current adjusting module is connected with the input of described feedback control module, the output of described feedback control module is connected with the feedback input end of described DC/DC control module respectively and is connected the control end of constant current adjusting module and connects, and the drive output of described DC/DC control module is connected with the control end of described boost module.
The multipath LED constant current control circuit that the present invention proposes, export LED string module to after by boost module the input voltage of power supply being boosted, the electric current that flows through each paths of LEDs string produces a sampled voltage in the constant current adjustment unit of correspondence, control by feedback control module, the sampled voltage of minimum is fed back to the DC/DC control module, with the ratio of boosting of control boost module, regulation output voltage; Simultaneously, adopt minimum current in each paths of LEDs string as benchmark, export control signal by feedback control module to the constant current adjusting module, the two-way selector of controlling in each constant current adjustment unit is selected different voltage references, so that the electric current of remaining LED string all regulates by adjusting pipe take minimum current as benchmark, and then so that the electric current of every paths of LEDs string equate, realize that the luminosity of every paths of LEDs string equates, improve the precision of constant current control, strengthen the uniformity of LED luminosity.
Description of drawings
Fig. 1 is the electrical block diagram of prior art LED constant-current control circuit one embodiment;
Fig. 2 is the electrical block diagram of another embodiment of prior art LED constant-current control circuit;
Fig. 3 is the electrical block diagram of the another embodiment of prior art LED constant-current control circuit;
Fig. 4 is the theory diagram of multipath LED constant current control circuit of the present invention preferred embodiment;
Fig. 5 is the electrical block diagram of multipath LED constant current control circuit of the present invention preferred embodiment;
Fig. 6 is the internal circuit configuration schematic diagram of DC/DC control chip in the multipath LED constant current control circuit of the present invention.
The realization of the object of the invention, functional characteristics and advantage are described further with reference to accompanying drawing in connection with embodiment.
Embodiment
Further specify technical scheme of the present invention below in conjunction with Figure of description and specific embodiment.Should be appreciated that specific embodiment described herein only in order to explain the present invention, is not intended to limit the present invention.
The present invention proposes a kind of multipath LED constant current control circuit.
With reference to Fig. 4, Fig. 4 is the theory diagram of multipath LED constant current control circuit of the present invention preferred embodiment.
In the embodiment of the invention, the multipath LED constant current control circuit comprises that supply module 10, boost module 20, DC/DC control module 30, LED go here and there module 40, constant current adjusting module 50 and feedback control module 60; In the present embodiment, boost module 20 is used for the voltage of supply module 10 inputs is boosted, increase output voltage, DC/DC control module 30 is used for the ratio of boosting of control boost module 20, regulation output voltage, LED string module 40 comprises at least two paths of LED string, be arranged in parallel between each paths of LEDs string and conducting direction identical, constant current adjusting module 50 is used for adjusting the electric current of each paths of LEDs string, feedback control module 60 is used for control constant current adjusting module 50 and adjusts electric current, so that the electric current of every paths of LEDs string equates.
Wherein, the input of boost module 20 is connected with supply module 10, the output of boost module 20 is connected with the input of LED string module 40, the output of LED string module 40 is connected with the input of constant current adjusting module 50, the output of constant current adjusting module 50 is connected with the input of feedback control module 60, the output of feedback control module 60 is connected respectively the control end of being connected with the constant current adjusting module and connects with the feedback input end of DC/DC control module 30, the drive output of DC/DC control module 30 is connected with the control end of boost module 20.
Present embodiment will export LED string module 40 to after will boosting from the input voltage of supply module 10 inputs by boost module 20, the electric current that flows through the LED string produces sampled voltage in constant current adjusting module 50, all sampled voltages are fed back to feedback control module 60 and process, feedback control module 60 with the minimum value in all sampled voltages as benchmark, export the minimum value in all sampled voltages to DC/DC control module 30, DC/DC control module 30 is according to the sampled voltage of minimum, and the output drive control signal is with the ratio of boosting of control boost module 20; Simultaneously, feedback control module 60 outputs control signals to constant current adjusting module 50 according to the size of all sampled voltages, adjusts the electric current of every paths of LEDs string in the LED string module 40 with control constant current adjusting module 50, so that the electric current of every paths of LEDs string is equal, realize that the luminosity of every paths of LEDs string equates.
With reference to Fig. 4 and Fig. 5, wherein Fig. 5 is the electrical block diagram of multipath LED constant current control circuit of the present invention preferred embodiment.
In above-described embodiment, boost module 20 comprises inductance L 1, diode D1, capacitor C 1 and switching tube M0; One end of inductance L 1 is connected with supply module 10 as the input of boost module 20, the anodic bonding of the other end of inductance L 1 and diode D1, and the other end of inductance L 1 is connected with the drain electrode of switching tube M0; The grid of switching tube M0 is connected with the output of DC/DC control module 30, the source ground of switching tube M0; The negative electrode of diode D1 is through capacitor C 1 ground connection, and the negative electrode of diode D1 is connected with the input of each paths of LEDs string respectively.
In the present embodiment, the topological structure by inductance L 1, diode D1, capacitor C 1 and switching tube M0 form the Boost booster circuit will boost according to the ratio of boosting that sets from the input voltage of supply module 10 inputs, to realize the adjusting to output voltage.
Particularly, the switching tube M0 in the boost module 20 is the NMOS pipe.
In conjunction with Fig. 4 to Fig. 6, wherein Fig. 6 is the internal circuit configuration schematic diagram of DC/DC control chip 301 in the multipath LED constant current control circuit of the present invention.
In above-described embodiment, DC/DC control module 30 comprises DC/DC accessory power supply VCC and DC/DC control chip 301, the positive pole of DC/DC accessory power supply VCC is connected with the power end of DC/DC control chip 301, and the negative pole of DC/DC accessory power supply VCC is connected with the earth terminal of DC/DC control chip 301.DC/DC accessory power supply VCC provides operating voltage for DC/DC control module 30.
Particularly, DC/DC control chip 301 comprises reference power supply V_REF, error amplifier AMP1, comparator C OMP1 and driver element DRV1; The positive pole of reference power supply V_REF is connected with the in-phase input end of error amplifier AMP1, the minus earth of reference power supply V_REF, and reference power supply V_REF provides reference voltage V ref for error amplifier AMP1; The output of error amplifier AMP1 is connected with the inverting input of comparator C OMP1; The in-phase input end of comparator C OMP1 is connected with sawtooth waveforms input STW, and the output of comparator C OMP1 is connected with the input of driver element DRV1; The output of driver element DRV1 is connected with the grid of switching tube M0 as the drive output DRIVER of DC/DC control module 30.
In above-described embodiment, each paths of LEDs string comprises some series connection and the identical LED of conducting direction, present embodiment describes as an example of 3 paths of LEDs strings example, in Fig. 5, the first paths of LEDs string 401 comprises N series connection and the identical LED LED11 ~ LED1N of conducting direction, the second paths of LEDs string 402 comprises N series connection and the identical LED LED21 ~ LED2N of conducting direction, Third Road LED string 403 comprises N series connection and the identical LED LED31 ~ LED3N of conducting direction, wherein N is positive integer, the anode tap of each paths of LEDs string is as the input of each paths of LEDs string, and all the negative electrode with diode D1 is connected.
When regulating the electric current of each paths of LEDs string, the employing current minimum compares the electric current in each paths of LEDs string and current minimum as benchmark, and then regulates the electric current in each paths of LEDs string, so that the electric current in every paths of LEDs string equates with current minimum, realize that the electric current in every paths of LEDs string equates.
In above-described embodiment, constant current adjusting module 50 comprises at least two the constant current adjustment units corresponding with the LED string, and the input of each constant current adjustment unit is connected with the cathode terminal of LED string.Present embodiment also describes as an example of 3 constant current adjustment units example, in Fig. 5, the input of the first constant current adjustment unit 501 is connected with the cathode terminal of LED string 401, the input of the second constant current adjustment unit 502 is connected with the cathode terminal of the 2nd LED string 402, and the input of the 3rd constant current adjustment unit 503 is connected with the cathode terminal of the 3rd LED string 403.
Particularly, each constant current adjustment unit comprises adjustment pipe, sampling resistor, operational amplifier and two-way selector.As shown in Figure 5, the first constant current adjustment unit 501 comprises that first adjusts pipe M1, the first sampling resistor RS1, the first operational amplifier OP1 and the first two-way selector MUX1, the second constant current adjustment unit 502 comprises that second adjusts pipe M2, the second sampling resistor RS2, the second operational amplifier OP2 and the second two-way selector MUX2, and the 3rd constant current adjustment unit 503 comprises that the 3rd adjusts pipe M3, the 3rd sampling resistor RS3, the 3rd operational amplifier OP3 and the 3rd two-way selector MUX3.The structure of the first constant current adjustment unit 501, the second constant current adjustment unit 502 and the 3rd constant current adjustment unit 503 is with all identical with the annexation of other modules, and the below describes as an example of the first constant current adjustment unit 501 example:
First adjusts the drain electrode of pipe M1 as the input of the first constant current adjustment unit 501, be connected with the cathode terminal of LED string 401, first adjusts the source electrode of pipe M1 through the first sampling resistor RS1 ground connection, and the first source electrode of adjusting pipe M1 is connected with the input pin that the inverting input of the first operational amplifier OP1 is connected with feedback control module respectively, and the first grid of adjusting pipe M1 is connected with the output of the first operational amplifier OP1; The in-phase input end of the first operational amplifier OP1 is connected with the output of the first two-way selector MUX1; The first input end of the first two-way selector MUX1 is connected with an output pin of feedback control module 60, and the first input end of the first two-way selector MUX1 is connected with the inverting input of error amplifier AMP1, the inverting input of error amplifier AMP1 is as the feedback input end ISEN of DC/DC control module 30, the second input of the first two-way selector MUX1 is connected with the positive pole of reference power supply V_REF, and the control end of the first two-way selector MUX1 is connected with another output pin of feedback control module 60.
In the present embodiment, feedback control module 60 is an integrated circuit (IC) chip, have as a plurality of input pins of the input of feedback control module 60 with as a plurality of output pins of the output of feedback control module 60, and feedback control module 60 built-in detection short circuit and function of open, when the short circuit of a certain paths of LEDs string or open circuit are arranged, the electric current of this paths of LEDs string does not compare with current minimum, avoided when LED string short circuit or open circuit are arranged, cause the misoperation of feedback control module 60, affect constant current and adjust the result.
Particularly, the adjustment pipe in each constant current adjustment unit is that NMOS manages, i.e. the first adjustment pipe M1, the second adjustment pipe M2 and the 3rd adjustment managed M3 and adopted NMOS to manage.Present embodiment preferably adopts the NMOS pipe as adjusting pipe, and the electric current that pipe is regulated every paths of LEDs string is adjusted in utilization.What deserves to be explained is in addition, can also select PMOS pipe, PNP triode or NPN triode as adjusting pipe, just for PMOS pipe and PNP triode, need to change itself and operational amplifier, and the annexation of operational amplifier and two-way selector, for example select the PMOS pipe, take the first constant current adjustment unit 501 as example, above-mentioned annexation should be: the drain electrode of a PMOS pipe is through the first sampling resistor RS1 ground connection, and be connected with the in-phase input end of the first operational amplifier OP1, the source electrode of a PMOS pipe is connected with the cathode terminal of LED string 401; The inverting input of the first operational amplifier OP1 is connected with the output of the first two-way selector MUX1.
The operation principle of multipath LED constant current control circuit of the present invention specifically describes as follows:
At first need to prove, the embodiment of the invention is when regulating the electric current of each paths of LEDs string, can adopt minimum value, maximum or the median of electric current to regulate as benchmark, the embodiment of the invention preferably adopts the minimum value of electric current as benchmark, therefore the minimum value of employing in all sampled voltages that each paths of LEDs string produces namely adopts minimum sampled voltage Vmin as benchmark as benchmark.The below is to adopt minimum sampled voltage Vmin to describe as example as benchmark.
Pass through the voltage of exporting after boost module 20 boosts in the default ratio of boosting after boosting from the input voltage VIN of supply module 10 inputs, be output voltage VO UT, output voltage VO UT is input to respectively in each paths of LEDs string, and the LED that drives in each paths of LEDs string lights.Wherein, the ratio of boosting of boost module 20 determines that by the duty ratio D of the drive control signal of switching tube M0 grid output in the DC/DC control module 30 relational expression that the duty ratio D of input voltage VIN, output voltage VO UT and drive control signal satisfies is: D=1-VIN/VOUT.Can find out that from formula the duty ratio D of drive control signal is larger, output voltage VO UT is higher.
The electric current that flows through each paths of LEDs string produces sampled voltage at sampling resistor, such as label V1, V2 and the V3 among Fig. 5, electric current I 1 in the first paths of LEDs string 401 produces the first sampled voltage V1 at the first sampling resistor RS1, electric current I 2 in the second paths of LEDs string 402 produces the second sampled voltage V2 at the second sampling resistor RS2, and the electric current I 3 in the Third Road LED string 403 produces the 3rd sampled voltage V3 at the 3rd sampling resistor RS3.
The the first sampled voltage V1 that produces, the second sampled voltage V2 and the 3rd sampled voltage V3 are fed back to respectively three inputs of feedback control module 60, process by feedback control module 60.Such as label Vmin, ctrl1, ctrl2 and the ctrl3 among Fig. 5, feedback control module 60 is selected minimum sampled voltage Vmin output among the first sampled voltage V1, the second sampled voltage V2 and the 3rd sampled voltage V3 by an output, outputs to respectively the first input end of feedback input end ISEN, the first two-way selector MUX1 of DC/DC control module 30, the first input end of the second two-way selector MUX2 and the first input end of the 3rd two-way selector MUX3; Simultaneously, other three outputs in feedback control module 60 are exported respectively the first control signal ctrl1, the second control signal ctrl2, the 3rd control signal ctrl3, and the first control signal ctrl1, the second control signal ctrl2, the 3rd control signal ctrl3 are outputed to respectively the control end of the first two-way selector MUX1, the control end of the second two-way selector MUX2 and the control end of the 3rd two-way selector MUX3.
The first two-way selector MUX1, the second two-way selector MUX2 and the 3rd two-way selector MUX3 select to export minimum sampled voltage Vmin or reference voltage V ref to the first operational amplifier OP1, the second operational amplifier OP2 and the 3rd operational amplifier OP3 according to the level state of the first control signal ctrl1, the second control signal ctrl2, the 3rd control signal ctrl3.
In the present embodiment, if the sample voltage value that a certain paths of LEDs string produces is minimum value, the control signal that then exports this paths of LEDs string to is high level, and the control signal that exports other roads to is low level.For example: if the first sampled voltage V1 is minimum value, then the first control signal ctrl1 is high level, and the second control signal ctrl2, the 3rd control signal ctrl3 are low level; Because the first control signal ctrl1 is high level, therefore the first two-way selector MUX1 output reference voltage Vref is in the first operational amplifier OP1, among the first operational amplifier OP1 the difference of reference voltage V ref and the first sampled voltage V1 is amplified, pipe M1 is adjusted in difference after amplification control first so that the first sampled voltage V1 strict equal reference voltage V ref; The second control signal ctrl2 is low level, the second two-way selector MUX2 exports minimum sampled voltage Vmin in the second operational amplifier OP2, the second operational amplifier OP2 amplifies the difference of minimum sampled voltage Vmin and the second sampled voltage V2, pipe M2 is adjusted in difference after amplification control second so that the second sampled voltage V2 strict equal minimum sampled voltage Vmin; In like manner the 3rd sampled voltage V3 is strict equals minimum sampled voltage Vmin; Because the first sampled voltage V1 is minimum value, so V1=V2=V3=Vref, the resistance of the first sampling resistor RS1, the second sampling resistor RS2 and the 3rd sampling resistor RS3 equates, be RS1=RS2=RS3, so electric current I 1=I2=I3=Vref/RS1 in each paths of LEDs string, thereby the electric current of each paths of LEDs string just can equate.In the practical application, because reference voltage V ref produces by built-in reference power supply V_REF in DC/DC control module 30, can not change, and the first sampling resistor RS1, the second sampling resistor RS2 and the 3rd sampling resistor RS3 are non-essential resistances, therefore can change by the resistance of selecting the first sampling resistor RS1, the second sampling resistor RS2 and the 3rd sampling resistor RS3 the electric current in each paths of LEDs string, reach the purpose that the electric current of regulating in each paths of LEDs string accurately equates it.
In the DC/DC control module 30, error amplifier AMP1 is amplifying from the minimum sampled voltage Vmin of feedback input end ISEN input and the difference of reference voltage V ref, difference after the amplification compares with the sawtooth signal of inputting from sawtooth waveforms input STW, export a string square-wave signal, square-wave signal is exported drive control signal to switching tube M0 through over-drive unit DRV1, raising is controlled boost module 20 regulation output voltage VOUT to the driving force of switching tube M0.
In embodiments of the present invention, feedback voltage equals minimum sampled voltage Vmin, so be at Vref/RS1 the current-clamp of the LED at minimum sampled voltage Vmin place string (such as LED string 401), the electric current of all the other LED strings then needs to adjust by adjusting pipe, so that current difference is reduced to minimum between every paths of LEDs string.
What deserves to be explained is because to cause the unequal factor of electric current between each paths of LEDs string mainly be sampling resistor, therefore as long as the precision of sampling resistor be ± 1%, then the current precision of each paths of LEDs string also substantially be ± 1%.
The multipath LED constant current control circuit that the present invention proposes, export LED string module 40 to after will boosting from the input voltage of supply module 10 input by boost module 20, the electric current that flows through each paths of LEDs string produces a sampled voltage in the constant current adjustment unit of correspondence, control by feedback control module 60, the sampled voltage of minimum is fed back to DC/DC control module 30, with the ratio of boosting of control boost module 20, regulation output voltage; Simultaneously, adopt minimum current in each paths of LEDs string as benchmark, export control signals by feedback control module 60 to constant current adjusting module 50, the two-way selector of controlling in each constant current adjustment unit is selected different voltage references, so that the electric current of remaining LED string all regulates by adjusting pipe take minimum current as benchmark, and then so that the electric current of every paths of LEDs string equate, realize that the luminosity of every paths of LEDs string equates, improve the precision of constant current control, strengthen the uniformity of LED luminosity.
The present invention also proposes a kind of led light source control system, this led light source control system comprises the multipath LED constant current control circuit, the circuit structure of this multipath LED constant current control circuit is identical with circuit structure and the operation principle of the multipath LED constant current control circuit described in above-described embodiment with operation principle, repeats no more herein.
The above only is the preferred embodiments of the present invention; be not so limit claim of the present invention; every equivalent structure or equivalent flow process conversion that utilizes specification of the present invention and accompanying drawing content to do; or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the present invention.
Claims (10)
1. multipath LED constant current control circuit, the boost module that comprise supply module, is used for input voltage is boosted, be used for controlling described boost module boost DC/DC control module and the LED string module of ratio, described LED string module comprises at least two paths of LED string, it is characterized in that described multipath LED constant current control circuit also comprises for the constant current adjusting module of the electric current of adjusting the described LED string in each road and is used for controlling the feedback control module that described constant current adjusting module is adjusted electric current; Wherein:
The input of described boost module is connected with described supply module, output is connected with the input of described LED string module, the output of described LED string module is connected with the input of described constant current adjusting module, the output of described constant current adjusting module is connected with the input of described feedback control module, the output of described feedback control module respectively with the feedback input end of described DC/DC control module be connected the control end of constant current adjusting module and be connected, the drive output of described DC/DC control module is connected with the control end of described boost module.
2. multipath LED constant current control circuit as claimed in claim 1 is characterized in that, described boost module comprises inductance, diode, electric capacity and switching tube; One end of described inductance is connected with described supply module as the input of described boost module, the other end of described inductance and the anodic bonding of described diode, and be connected with the drain electrode of described switching tube; The grid of described switching tube is connected with the output of described DC/DC control module, the source ground of described switching tube; The negative electrode of described diode is through described capacity earth, and is connected with the input of the described LED string in each road respectively.
3. multipath LED constant current control circuit as claimed in claim 2 is characterized in that, described switching tube is the NMOS pipe.
4. multipath LED constant current control circuit as claimed in claim 1 or 2, it is characterized in that, described DC/DC control module comprises DC/DC accessory power supply and DC/DC control chip, the positive pole of described DC/DC accessory power supply is connected with the power end of described DC/DC control chip, and the negative pole of described DC/DC accessory power supply is connected with the earth terminal of described DC/DC control chip.
5. multipath LED constant current control circuit as claimed in claim 4 is characterized in that, described DC/DC control chip comprises reference power supply, error amplifier, comparator and driver element; The positive pole of described reference power supply is connected with the in-phase input end of described error amplifier, the minus earth of described reference power supply; The output of described error amplifier is connected with the inverting input of described comparator; The in-phase input end of described comparator is connected with the sawtooth waveforms input, and the output of described comparator is connected with the input of described driver element; The output of described driver element is connected with the grid of described switching tube as the output of described DC/DC control module.
6. multipath LED constant current control circuit as claimed in claim 1 or 2 is characterized in that, the described LED string in each road comprises some series connection and the identical LED of conducting direction, and the anode tap of the described LED string in each road all is connected with the negative electrode of described diode.
7. multipath LED constant current control circuit as claimed in claim 1, it is characterized in that, described constant current adjusting module comprises at least two the constant current adjustment units corresponding with described LED string, and the input of each described constant current adjustment unit is connected with the cathode terminal of a described LED string.
8. multipath LED constant current control circuit as claimed in claim 7 is characterized in that, each described constant current adjustment unit comprises adjusts pipe, sampling resistor, operational amplifier and two-way selector; Wherein:
The drain electrode of described adjustment pipe is as the input of described constant current adjustment unit, connect with the cathode terminal of corresponding one described LED string, the source electrode of described adjustment pipe is through described sampling resistor ground connection, and respectively with the inverting input of described operational amplifier be connected an input pin of feedback control module and be connected, the grid of described adjustment pipe is connected with the output of described operational amplifier; The in-phase input end of described operational amplifier is connected with the output of described two-way selector; The first input end of described two-way selector is connected with an output pin of described feedback control module, and be connected with the inverting input of described error amplifier, the second input of described two-way selector is connected with the positive pole of described reference power supply, and the control end of described two-way selector is connected with another output pin of described feedback control module.
9. multipath LED constant current control circuit as claimed in claim 8 is characterized in that, described adjustment pipe is the NMOS pipe.
10. a led light source control system is characterized in that, comprises each described multipath LED constant current control circuit in the claim 1 to 9.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310003575.4A CN103037597B (en) | 2013-01-06 | 2013-01-06 | Multi-channel LED (Light Emitting Diode) constant current control circuit and LED light source control system |
| HK13110571.1A HK1183399A1 (en) | 2013-01-06 | 2013-09-13 | Multi-channel led (light emitting diode) constant current control circuit and led light source control system led led |
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| CN201310003575.4A CN103037597B (en) | 2013-01-06 | 2013-01-06 | Multi-channel LED (Light Emitting Diode) constant current control circuit and LED light source control system |
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| CN103037597A true CN103037597A (en) | 2013-04-10 |
| CN103037597B CN103037597B (en) | 2015-03-25 |
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| CN103458578A (en) * | 2013-08-27 | 2013-12-18 | 青岛海信电器股份有限公司 | Light-emitting diode (LED) driving system and method and LED display device |
| CN103606354A (en) * | 2013-11-25 | 2014-02-26 | 深圳市华星光电技术有限公司 | LED backlight driving circuit and liquid crystal display |
| CN103648216A (en) * | 2013-12-06 | 2014-03-19 | 武汉精立电子技术有限公司 | Intelligent constant-current high-power LED driving method |
| CN103648215A (en) * | 2013-12-06 | 2014-03-19 | 武汉精立电子技术有限公司 | Intelligent adjustable high-power LED driving device |
| CN103874296A (en) * | 2014-03-21 | 2014-06-18 | 武汉精测电子技术股份有限公司 | LED constant-current driving circuit of multi-path self-adaptive loads |
| CN104253960A (en) * | 2014-09-17 | 2014-12-31 | 广州视源电子科技股份有限公司 | Low-power-consumption voltage-stabilizing backlight control circuit and television |
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| CN107071980A (en) * | 2017-05-08 | 2017-08-18 | 生迪智慧科技有限公司 | Multichannel LED drive circuit |
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| CN103458578A (en) * | 2013-08-27 | 2013-12-18 | 青岛海信电器股份有限公司 | Light-emitting diode (LED) driving system and method and LED display device |
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| CN103606354B (en) * | 2013-11-25 | 2016-04-13 | 深圳市华星光电技术有限公司 | Led backlight drive circuit and liquid crystal display |
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| WO2016184169A1 (en) * | 2015-05-19 | 2016-11-24 | 深圳创维－Rgb电子有限公司 | Multi-channel dual-mode digital control led driving circuit and led lamp |
| US10143072B2 (en) | 2015-05-19 | 2018-11-27 | Shenzhen Skyworth-Rgb Electronic Co., Ltd | Multi-channel dual-mode digital control LED driving circuit and LED lamp |
| CN107071980A (en) * | 2017-05-08 | 2017-08-18 | 生迪智慧科技有限公司 | Multichannel LED drive circuit |
| CN108966416A (en) * | 2018-07-11 | 2018-12-07 | 昆山仕优威电子科技有限公司 | A kind of control system of UV LED light source |
| CN109152132A (en) * | 2018-08-16 | 2019-01-04 | 西安电子科技大学 | A kind of LED multi-path light adjusting circuit |
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| CN111796150A (en) * | 2019-04-08 | 2020-10-20 | 华润矽威科技（上海）有限公司 | Duty ratio detection circuit and duty ratio detection method |
| CN111796150B (en) * | 2019-04-08 | 2023-09-22 | 华润微集成电路(无锡)有限公司 | Duty cycle detection circuit and duty cycle detection method |
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| CN103037597B (en) | 2015-03-25 |
| HK1183399A1 (en) | 2013-12-20 |
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