CN207612441U - LED parallel current-equalizing circuits - Google Patents
LED parallel current-equalizing circuits Download PDFInfo
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- CN207612441U CN207612441U CN201721551685.4U CN201721551685U CN207612441U CN 207612441 U CN207612441 U CN 207612441U CN 201721551685 U CN201721551685 U CN 201721551685U CN 207612441 U CN207612441 U CN 207612441U
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Abstract
The utility model discloses a kind of LED parallel current-equalizing circuits, including power supply circuit, the control circuit and driving circuit being connect with power supply circuit, the LED multi-path lamp string being connect with the driving circuit and sample circuit being connect respectively with control circuit and LED light string；Sample circuit is used to acquire the actual current value of each paths of LEDs lamp string；Control circuit is used to determine the way of work LED light string according to the actual current value for getting the collected each paths of LEDs lamp string of sample circuit, and sends pwm control signal to driving circuit；Driving circuit is used for according to the pwm control signal that control circuit is sent out is received, and control flows through the total current of each paths of LEDs lamp string and the electric current of each paths of LEDs lamp string branch, the electric current to flow through each paths of LEDs lamp string remain unchanged.It is inconvenient to solve the problems, such as that existing multi-channel LED current equalization controls for LED parallel current-equalizing circuits in the utility model.
Description
Technical field
The utility model is related to technical field of LED illumination, more particularly to a kind of LED parallel current-equalizing circuits.
Background technology
Light emitting diode (LED) is a kind of solid-state semiconductor device that can convert electrical energy into visible light, it can be straight
It connects and converts electricity to light, due to having the advantages that luminous efficiency is high, be easy to control, low-voltage direct driving, with long service life, thus
LED is widely used.
The application of LED can be divided mainly into three categories：LCD screen backlight, LED illumination, LED are shown.Major part LCD TV at present
Machine/indicator screen, laptop LCD display be use CCFL fluorescent tubes do backlight, because CCFL fluorescent tubes exist
Service life is relatively short, relatively not environmentally the deficiencies of, the backlight of above-mentioned display screen is positive at present to be developed towards using LED backlight.By LCD
The size of screen generally requires dozens of and does backlight to a white light LEDs up to a hundred.Existing LCD screen backlight usually will then use parallel connection
Mode.But since single led impedance has differences, there are the unequal situations of electric current between different LED, this will cause respectively
A LED shines and differs, and influences backlight effect, in addition can the larger LED of convection current overcurrent damage, therefore need to LED into
Row current sharing control.
As shown in fig. 6, the conceptual scheme of traditional multi-channel LED current equalization control, the program are made of three parts, respectively TV is hard
Part module, power supply module, constant current output module composition.Wherein constant current output module mainly controls each LED realizations and flows, permanent
It includes multichannel brightness adjustment control chip, current-sharing module, sampling/protection module, LED backlight 1-4 to flow output module.It is wherein existing to flow
In control program, independent multichannel brightness adjustment control chip is needed to implement the control of multi-channel LED current equalization, and the control chip needs
The core controller of TV hardware modules individually sends enabling signal and drive signal to drive constant current output, therefore implements
Relatively complicated and cost is higher, and since multichannel brightness adjustment control chip pin is limited, is if desired driven to the LED of more multichannel
Control, then need multi-disc multichannel brightness adjustment control chip, there is larger limitation to the dilatation of system.
Utility model content
Based on this, the purpose of this utility model is that proposing a kind of LED parallel current-equalizing circuits, it is equal to solve existing LED multi-path
The inconvenient problem of flow control.
The embodiments of the present invention provide a kind of LED parallel current-equalizing circuits, and specific technical solution is as follows：
A kind of LED parallel current-equalizing circuits, including power supply circuit and LED multi-path lamp string can connect not per LED light string described in road
With the LED light of quantity, the LED parallel current-equalizing circuits further include control circuit, driving circuit and sample circuit；
The sample circuit is connect with the LED light string and the control circuit respectively, for acquiring LED light described in each road
The actual current value of string, and the actual current value is sent to the control circuit；
The control circuit is connect with the power supply circuit, the sample circuit and the driving circuit respectively, is used for root
According to the actual current value of LED light string described in each road, pwm control signal is sent to the driving circuit；
The driving circuit is connect with LED light string described in the power supply circuit, the control circuit and each road respectively, is used
In the pwm control signal sent out according to the control circuit is received, control flows through the total current of LED light string described in each road
And the electric current of LED light string branch described in each road, the electric current to flow through LED light string described in each road remain unchanged.
LED parallel current-equalizing circuits provided by the utility model can acquire the reality of each paths of LEDs lamp string by sample circuit
The work way of current value and total LED light string, control circuit send out pwm control signal according to the signal that sample circuit acquires
To driving circuit so that driving circuit driving output to each paths of LEDs lamp string total electric current and flow through each paths of LEDs lamp string branch
Size of current remain unchanged, realize the stream of LED multi-path lamp string, control mode is simple and convenient, solves existing multichannel
The inconvenient problem of LED sharing controls.
In addition, according to LED parallel current-equalizing circuits provided by the utility model, there can also be following additional technology special
Sign：
Further, the control circuit includes first control circuit and second control circuit, and the driving circuit includes
First driving circuit and the second driving circuit,
The first control circuit is according to the current value for getting LED light string described in the collected every road of the sample circuit
Determine the way of work LED light string, and according to the rated current of the way of the work LED light string and the work LED light string
Value, which determines, sends out the first pwm control signal to the driving circuit, so that first driving circuit control flows through described in each road
The total current of LED light string；
The second control circuit is used for the current value according to the LED light string that works described in each road and the load current value tune
The duty ratio of second pwm control signal of the whole output to the driving circuit, so that second driving circuit drives each road institute
The current value stated in work LED light string is equal with the load current value.
Further, the power supply circuit include alternating current input power supplying, the filtered electrical that is connect with the alternating current input power supplying
Road and the circuit of reversed excitation being connect with the filter circuit；
The circuit of reversed excitation includes flyback primary circuit, the flyback transformer being connect with the flyback primary circuit, difference
The constant current-supplying circuit and constant pressure power supply circuit being connect with the flyback transformer；
The flyback transformer is made of primary coil, the first secondary coil and the second secondary coil, the flyback primary side
Circuit is connect with one end of the primary coil and the filter circuit respectively, the other end of the primary coil also with first
Effect pipe connects；First secondary coil is connect with the constant current-supplying circuit, for exporting constant current；Described second is secondary
Sideline circle is connect with the constant pressure power supply circuit, for exporting constant voltage.
Further, the both ends of the primary coil respectively with the flyback primary circuit and first field-effect tube
Drain electrode connection, the source electrode of first field-effect tube are connect with first resistor, and the grid of first field-effect tube connects a PWM
Signal, for being exported to first secondary coil and second secondary coil according to the Duty ratio control of the pwm signal
Energy；
The constant current-supplying circuit includes the first diode, the first capacitance and constant current inductance, first secondary coil
Both ends respectively with the anode of first diode and connect, the both ends of first capacitance respectively with first diode
Cathode and ground connect, the cathode of first diode also connect with one end of the constant current inductance, the constant current inductance
The other end is the constant current output end of the constant current-supplying circuit；
The constant pressure power supply circuit includes the second diode and the second capacitance, the both ends of second secondary coil respectively with
The anode of second diode and ground connection, the both ends of second capacitance cathode and ground with second diode respectively
Connection, the other end of second diode are the constant pressure output end of the constant pressure power supply circuit.
Further, first driving circuit includes the first triode being connect with the constant pressure power supply circuit, difference
The second triode and second resistance that are connect with first triode, the zener diode being connect respectively with the second resistance
With the second field-effect tube, and the 3rd resistor and third diode that are connect respectively with second field-effect tube；
Wherein, the collector of first triode is connect with the constant pressure output end, the transmitting of first triode
Pole is connect with one end of the emitter of second triode and the second resistance respectively, the base stage point of first triode
Do not connect with the base stage of second triode and the first control circuit, the collector of second triode respectively with number
Word and the zener diode anode connection, the other end of the second resistance cathode with the zener diode respectively
It being connected with the grid of second field-effect tube, the source electrode of second field-effect tube is connect with one end of the 3rd resistor,
The drain electrode of second field-effect tube is connect with the anode of the constant current output end and the third diode respectively, the third
The cathode of diode is connect with LED light string described in each road respectively, one third capacitance of the third diodes in parallel.
Further, second driving circuit include a third field-effect tube, the grid of the third field-effect tube with
Second control circuit connection, the source electrode ground connection of the third field-effect tube, the drain electrode of the third field-effect tube with it is corresponding
LED light string connection, the 2nd PWM that second driving circuit is sent out according to the second control circuit controls letter
Number duty cycle adjustment current switching time of the LED light string within each period length.
Further, the sample circuit includes an operational amplifier, the normal phase input end company with the operational amplifier
The first input circuit for connecing, the second input circuit being connect with the negative-phase input of the operational amplifier, respectively with the fortune
Calculate the compensation circuit connected between the negative-phase input and its output end of amplifier and the output end with the operational amplifier
The clamp circuit of connection, second input circuit are connect with the LED light string, and the clamp circuit connects with the control circuit
It connects, the electric current that the sample circuit is used to flow through the LED light string exports after differential amplification and amplitude limit clamper to described
Control circuit.
Further, first input circuit includes connect respectively with the normal phase input end of the operational amplifier
Four resistance, the 4th capacitance and the 5th resistance；
Second input circuit includes the 6th resistance, the Yi Jiyu being connect with the negative-phase input of the operational amplifier
6th resistance connects the 7th resistance, the 8th resistance and the 9th resistance, what the 6th resistance was connect with the 7th resistance
One end is also connect with the LED light string；
The compensation circuit includes the tenth resistance and the 5th capacitance, wherein the tenth resistance and the 5th capacitance are in parallel
It is connected between the negative-phase input and output end of the operational amplifier；
The clamp circuit includes the eleventh resistor being connect with the output end of the operational amplifier, respectively with described
The 6th capacitance and double diode of 11 resistance connection, the plus earth of a diode of the double diode, another two
The cathode of pole pipe is connect with power pins, for clamping down on output signal between the voltage that 0V and the power pins are provided.
Further, first field-effect tube, second field-effect tube, the third field-effect tube increase for N-channel
Strong type metal-oxide-semiconductor.
Description of the drawings
Fig. 1 is the structural schematic diagram for the LED parallel current-equalizing circuits that one embodiment of the utility model proposes.
Fig. 2 is the concrete structure schematic diagram for the LED parallel current-equalizing circuits that one embodiment of the utility model proposes.
Fig. 3 is the electrical block diagram for the LED parallel current-equalizing circuits that one embodiment of the utility model proposes.
Fig. 4 is the circuit structure signal of power supply circuit in the LED parallel current-equalizing circuits that one embodiment of the utility model proposes
Figure.
Fig. 5 is the JA(junction ambient) circuit of sample circuit in the LED parallel current-equalizing circuits that one embodiment of the utility model proposes
Structural schematic diagram.
Fig. 6 is the structural schematic diagram of LED parallel current-equalizing circuits in the prior art.
Specific implementation mode
To keep the above objects, features, and advantages of the utility model more obvious and easy to understand, below in conjunction with the accompanying drawings to this
The specific implementation mode of utility model is described in detail.Elaborate many details in order to abundant in the following description
Understand the utility model.But the utility model can be much to implement different from other manner described here, this field
Technical staff can do similar improvement without prejudice to the utility model connotation, therefore the utility model is not by following public affairs
The limitation for the specific implementation opened.
In the present invention unless specifically defined or limited otherwise, term " installation ", " connected ", " connection ", " Gu
It is fixed " etc. terms shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or be integrally connected；It can
Can also be electrical connection to be mechanical connection；It can be directly connected, can also indirectly connected through an intermediary, Ke Yishi
Connection inside two elements.For the ordinary skill in the art, above-mentioned term can be understood as the case may be
Concrete meaning in the present invention.Term " and or " used herein includes one or more relevant Listed Items
Any and all combinations.
It please refers to Fig.1 to Fig. 5, the LED parallel current-equalizing circuits 10 of the embodiment offer of the utility model, including power supply electricity
Road 20, the control circuit 30 being connect with power supply circuit 20 and driving circuit 40, the LED multi-path lamp string being connect with driving circuit 40
50 and the sample circuit 60 that is connect respectively with control circuit 30 and LED light string 50.It is in parallel between wherein each paths of LEDs lamp string 50
Connection, and the LED light for the different number that can connect per paths of LEDs lamp string 50.The power supply circuit 20 is for circuit 30 in order to control, driving electricity
Road 40, LED light string 50 provide required constant power voltage, and provide constant current for driving circuit 40.Wherein, control circuit
30 send out pwm control signal to driving electricity according to the actual current value determination of the collected each paths of LEDs lamp string of sample circuit 60 50
Road 40, so that the electric current that the control of driving circuit 40 flows through each paths of LEDs lamp string 50 remains unchanged.It is pointed out that the present embodiment
In, which is applied to television set, equal for being carried out to each LED in multiple LCD screen backlights in TV
Stream light modulation so that each LED in the TV can realize that brightness is consistent.Wherein, it is integrated with control in the hardware circuit in the TV
Circuit 30.
Further, power supply circuit 20 is connect with driving circuit 40 and control circuit 30 respectively.Wherein driving circuit 40 wraps
The first driving circuit 41 and multiple second driving circuits 42 are included, control circuit 30 includes first control circuit 31 and multiple second controls
Circuit 32 processed.Wherein power supply circuit 20 include alternating current input power supplying AC, connect with alternating current input power supplying AC filter circuit 21, with
And the circuit of reversed excitation 22 being connect with filter circuit 21.Wherein alternating current input power supplying AC is connect with filter circuit 21, in the present embodiment,
The filter circuit 21 includes at least electromagnetic interface filter, for inhibiting the High-frequency Interference in alternating current input power supplying AC.It is miscellaneous that it filters out high frequency
Alternating current after wave exports direct current after the processing of circuit of reversed excitation 22.
Further, circuit of reversed excitation 22 includes at least flyback primary circuit 23, flyback transformer TC, the first field-effect tube
Q1, first resistor R1, the first diode T1, the second diode T2, the first capacitance C1, the second capacitance C2 and constant current inductance L.Its
The output end of middle circuit of reversed excitation 22 includes constant current-supplying circuit 24 and constant pressure power supply circuit 25.Wherein flyback transformer TC is by primary side
Coil and secondary coil composition, be used for the energy transmission by primary coil to secondary coil, and by primary coil with pair sideline
Circle is isolated.Flyback primary circuit 23 is connect with filter circuit 21 and primary coil respectively, for will be transmitted after AC process
To primary coil.Wherein primary coil is the input stage of flyback transformer TC, and secondary coil is the output stage of flyback transformer TC,
It is used to export the energy of primary coil, wherein in the present embodiment, including two secondary coils, it is respectively the first secondary coil
With the second secondary coil.
Wherein one end of primary coil is connect with flyback primary circuit 23, the drain electrode d of the other end and the first field-effect tube Q1
Connection.The source electrode s of first field-effect tube Q1 is connect with one end of first resistor R1, the grid g accesses one of the first field-effect tube Q1
Pwm signal, the other end of first resistor R1 are connect with digitally SGND.The first field-effect tube of this in the present embodiment Q1 is N-channel
Enhanced metal-oxide-semiconductor, the pwm signal are used to control the size for the energy that primary coil is transmitted to secondary coil.It is when pwm signal
First field-effect tube Q1 conductings when high level, primary coil starts energy storage at this time.The first field-effect when pwm signal is low level
Pipe Q1 cut-offs, primary coil transfers energy to secondary coil at this time.Therefore the first field-effect tube Q1 believes according to the PWM of access
Number duty ratio, the size of the turn-on time within each period can be controlled so that control primary coil with certain
In energy transmission to secondary coil, wherein first resistor R1 can acquire the electric current of the first field-effect tube Q1, to prevent flyback
22 overcurrent of circuit.
Wherein, constant current-supplying circuit 24 includes the first diode T1, the first capacitance C1 and constant current inductance L.Wherein the 1st
The anode of pole pipe T1 is connect with one end of the first secondary coil, the other end ground connection of the first secondary coil, the first diode T1's
Cathode is connect with one end of one end of the first capacitance C1 and constant current inductance L respectively, wherein the other end ground connection of the first capacitance C1, permanent
The other end of galvanic electricity sense L is the constant current output end Is of constant current-supplying circuit 24, for exporting constant current.First in the present embodiment
Diode T1 is constant current rectification diode, is direct current electricity output by the AC rectification of the first secondary coil output end, and pass through
Constant electric current is exported after crossing constant current inductance L.
Wherein, constant pressure power supply circuit 25 includes the second diode T2 and the second capacitance C2.Second diode T2 anode with
One end of second secondary coil connects, the other end ground connection of the second secondary coil, the cathode and the second capacitance of the second diode T2
One end of C2 connects, the other end ground connection of the second capacitance C2.Wherein the first capacitance C1, the second capacitance C2 are used to reduce the straight of output
Ripple in galvanic electricity, the cathode of the second diode T2 are the constant pressure output end Us of constant pressure power supply circuit 25.Second in the present embodiment
Diode T2 is constant voltage rectifier diode, is direct current electricity output by the AC rectification of the first secondary coil output end, and should
The voltage stabilization of direct current is 12V, is used for circuit 30, driving circuit 40, LED light string 50 in order to control and provides required power supply electricity
Pressure.
Further, power supply circuit 20 is connect with driving circuit 40 and control circuit 30 respectively.Wherein driving circuit 40 wraps
The first driving circuit 41 and multiple second driving circuits 42 are included, control circuit 30 includes first control circuit 31 and multiple second controls
Circuit 32 processed.The control circuit 30 is integrated in the TV hardware circuits in TV, the input terminal of control circuit 30 respectively with multichannel
Sample circuit 60 connects, wherein being connected with corresponding LED light string 50 all the way per sample circuit 60 all the way, is used for acquisition and is connected thereto
LED light string 50 actual current value.The output end of first control circuit 31 is connect with the first driving circuit 41, is obtained for basis
Get the way that the collected actual current value per paths of LEDs lamp string 50 of multi-sampling circuit 60 determines work LED light string, and root
The first pwm control signal is sent out to the first driving according to the load current value determination of the way and work LED light string of work LED light string
Circuit 41, so that the control of the first driving circuit 41 is input to the total current size of LED multi-path lamp string 50.Each road second control circuit
Corresponding the second driving circuit of each road 42 of 32 difference connects, for collected right according to corresponding each road sample circuit 60
The actual current value for the LED light string 50 answered sends out corresponding second pwm control signal to corresponding second driving circuit 42, and
The duty ratio of the second pwm control signal is adjusted according to the actual current value of the acquisition, so that the second driving circuit 42 controls it
The current value of corresponding work LED light string is equal with load current value so that the size of current for flowing through each road work LED light string is protected
It holds constant.
Further, driving circuit 40 is connect with power supply circuit 20, control circuit 30 and LED multi-path lamp string 50 respectively,
Wherein driving circuit 40 includes the first driving circuit 41 and the second driving circuit 42, and the first driving circuit 41 is used for according to the first control
The first pwm control signal control that circuit 31 processed is sent out is input to the total current size of LED multi-path lamp string 50, each second driving
Circuit 42 is used to control its corresponding LED light string 50 according to the second pwm control signal that corresponding second control circuit 32 is sent out
The size of current of branch.
Wherein the first driving circuit 41 includes the first triode T1 being connect with constant pressure power supply circuit 25, respectively with the one or three
The the second triode T2 and second resistance R2 of pole pipe T1 connections, the zener diode D1 and second being connect respectively with second resistance R2
Field-effect tube Q2, and respectively with the second field-effect tube Q2 the 3rd resistor R3 connecting and third diode T3.Wherein the 1st
The collector c of pole pipe T1 is connect with the constant pressure output end Us of constant pressure power supply circuit 25, the emitter e of the first triode T1 respectively with
The emitter e of second triode T2 is connected with one end of second resistance R2, the base stage b of the first triode T1 respectively with the two or three pole
The base stage b and control circuit 30 of pipe T2 are connected, the collector c of the second triode T2 respectively with digitally SGND and zener diode
The anode connection of D1, the other end of the second resistance R2 grid with the cathode of zener diode D1 and the second field-effect tube Q2 respectively
The source electrode s of g connections, the second field-effect tube is connect with one end of 3rd resistor R3, the other end ground connection of 3rd resistor R3, second
The drain electrode d of effect pipe Q2 is connect with the anode of the constant current output end Is of constant current-supplying circuit 24 and third diode T3 respectively, the
The cathode of three diode T3 is connect with the anode of each paths of LEDs lamp string 50 respectively, wherein third diode T3 one third capacitances of parallel connection
C3。
Wherein the first triode T1 is NPN type triode, and the second triode T2 is PNP type triode, the first triode T1
Push-pull circuit is formed with the second triode T2, is powered by constant pressure power supply circuit 25, for sending out control circuit 30
The first pwm control signal gone out is amplified to form the first larger PWM drive signal of driving capability, and is exported by emitter e,
The first PWM drive signal is transferred to the grid g of the second field-effect tube Q2 after second resistance R2 at this time, and constant current-supplying circuit 24
Output end connect with the source electrode s of the second field-effect tube Q2, for flowing into after exporting constant current to the second field-effect tube Q2
Three diode T3, so that each paths of LEDs lamp string 50 works.In the present embodiment, the second field-effect tube Q2 is the enhanced metal-oxide-semiconductor of N-channel,
At this time when the first pwm control signal that first control circuit 31 is sent out is high level, then second field-effect tube Q2 is connected, because
The electric current of this constant current-supplying circuit 24 output flows through the second field-effect tube Q2 so that third diode T3 short circuit, at this time by the
Three capacitance C3 are discharged in each LED light string 50；When the first pwm control signal is low level, second field-effect tube Q2 is cut
Only, the electric current that the drain electrode d of the second field-effect tube Q2 is flowed through in constant current-supplying circuit 24 all flows into third diode T3.Therefore
By the duty ratio of the first pwm control signal of control, the turn-on time of the second field-effect tube Q2 within each period can be controlled,
So as to adjust the total current size being output in each paths of LEDs lamp string 50, after the total current flows through third diode T3 at this time
It separately flows into each paths of LEDs lamp string 50 so that each paths of LEDs lamp string 50 can work.However it cannot ensure to flow through each paths of LEDs
Electric current in lamp string 50 all keeps constant constant.Therefore each paths of LEDs lamp string 50 is controlled by the second driving circuit 42 of setting
In size of current so that each paths of LEDs lamp string 50 can by dynamic compensate after remain unchanged.
Wherein, the second driving circuit of each road 42 is connected with corresponding second control circuit 32 and LED light string 50 respectively, wherein
The second driving circuit of each road 42 includes a third field-effect tube Q3, the control electricity of the grid g of third field-effect tube Q3 and second
Road 32 connects, and the source electrode s ground connection of third field-effect tube Q3, the drain electrode d of third field-effect tube Q3 is connect with LED light string 50, at this time.
When the second pwm control signal that second control circuit 32 is sent out is high level, then third field-effect tube Q3 is connected, at this time
LED light string 50 is bright；When the second pwm control signal is low level, then third field-effect tube Q3 ends, at this time LED light string 50
It goes out, therefore the current switching time of the LED light string 50 within each period can be adjusted by the duty ratio of the second pwm control signal
Length, therefore may be implemented control LED light string 50 brightness.Second control circuit 32 is according to the sample circuit got at this time
The actual current value of 60 collected LED light strings 50 can send out the second pwm control signal to the second driving circuit 42, so that
Second driving circuit 42 controls LED light string 50 and carries out stream light modulation.For example, be I1 to each paths of LEDs lamp string 50 setting rated current,
When sample circuit 60 collects the actual current value of the LED light string 50, and sending controling circuit 30, wherein control circuit all the way for certain
30 actual current values for getting the acquisition of sample circuit 60 are I2, and I2 is more than I1, and second control circuit 32 is sent out new at this time
In second pwm control signal to corresponding second driving circuits of the LED 42, wherein second pwm control signal is adjusted to more former
First duty ratio reduces, and at this time after the driving of the second driving circuit 42, the current value for flowing through LED light string 50 is reduced, at this time
By PID electric current loops adjust pass through each paths of LEDs lamp string 50 current value can dynamic regulation, to maintain to flow.
Further, sample circuit 60 is connect with control circuit 30 and LED light string 50 respectively.Wherein, sample circuit 60 wraps
Include an operational amplifier U, the first input circuit 61 for being connect with the normal phase input end of operational amplifier U, with operational amplifier U's
Second input circuit 62 of negative-phase input connection connects between the negative-phase input of operational amplifier U and its output end respectively
The compensation circuit 63 connect and the clamp circuit 64 being connect with the output end of operational amplifier U.Wherein the first input circuit 61 wraps
The 4th resistance R4, the 4th capacitance C4 and the 5th resistance R5 being connect respectively with the normal phase input end of operational amplifier U are included, wherein
The other end of 4th resistance R4, the 4th capacitance C4 and the 5th resistance R5 are grounded.4th resistance R4 and the 4th capacitance C4 compositions are low
Bandpass filter.Wherein the second input circuit 62 include the 6th resistance R6 being connect with the negative-phase input of operational amplifier U and
It connect the 7th resistance R7, the 8th resistance R8 and the 9th resistance R9 with the 6th resistance R6.Wherein the 6th resistance R6 and the 7th resistance R7
One end of connection is also connect with LED light string 50, wherein the 7th resistance R7, the 8th resistance R8 and the 9th resistance R9 are in parallel and another
End ground connection.Compensation circuit 63 includes the tenth resistance R10 and the 5th capacitance C5.Wherein the tenth resistance R10 and the 5th capacitance C5 are in parallel
It is connected between the negative-phase input and output end of operational amplifier U.Clamp circuit 64 includes the output end with operational amplifier U
The eleventh resistor R11 of connection, the 6th capacitance C6 being connect respectively with eleventh resistor R11 and double diode D2, wherein the 6th
The other end of capacitance C6 is grounded, the plus earth of a diode of double diode D2, the cathode and power supply of another diode
Pin VCC connections, wherein power pins VCC are 3.3V, for clamping down on output signal between 0-3.3V.The wherein clamper
The output end of circuit 64 is connect with control circuit 30 and eleventh resistor R11 is connected with control with the one end connecting the 6th capacitance C6
Circuit 30 processed.The specific works of the sample circuit 60 are, the electric current of LED light string 50 flow through the 7th resistance R7, the 8th resistance R8 and
After 9th resistance R9, it converts its current signal to voltage signal, and be input to the negative-phase input of operational amplifier U, through fortune
It is exported from its output end after calculating the differential amplification processing of amplifier U, wherein output signal carries out signal after clamp circuit 64
Amplitude limit is to clamp down between 0-3.3V.And in output to control circuit 30 so that control circuit 30 can obtain every paths of LEDs lamp string
50 actual current value.
Further, the specific works of the LED parallel current-equalizing circuits 10 are circuit 30 and the driving in order to control of power supply circuit 20
Circuit 40 is powered, and driving circuit 40 drives the total current for flowing through each paths of LEDs lamp string 50 and the circuit to 50 branch of LED light string,
Sample circuit 60 acquires the actual circuit of each paths of LEDs lamp string 50 and the work way of LED light string 50 at this time, and is sent to control
Circuit 30 processed, control circuit 30 flow through total electricity of each paths of LEDs lamp string 50 according to the control of the working ways number of the LED light string 50 got
Stream, for example, 50 a total of roads N of LED light string, work when having collected M paths of LEDs lamp string 50 according to sample circuit 60, i.e., have at this time
N-M paths of LEDs lamp string 50 is in non-working condition of opening a way, and control circuit 30 is corresponding according to the ratio of 50 reduction of LED light string at this time
The duty ratio for adjusting the first pwm control signal sent out, so that the total current for flowing into each paths of LEDs lamp string 50 is accordingly reduced.And
Control circuit 30 is according to the actual current value of each paths of LEDs lamp string 50 got, the 2nd PWM of corresponding dynamic adjustment output
The duty ratio of signal is controlled, so that constant state is flowed in the electric current maintenance for flowing into each paths of LEDs lamp string 50 so that in TV
LED backlight is uniform.
LED parallel current-equalizing circuits provided by the utility model can acquire the reality of each paths of LEDs lamp string by sample circuit
Current value, control circuit send out pwm control signal to driving circuit, so that driving circuit drives according to the signal that sample circuit acquires
Dynamic output to each paths of LEDs lamp string total electric current and flow through the size of current of each paths of LEDs lamp string branch and remain unchanged, realize
The stream of LED multi-path lamp string.When opening a way there are certain road in LED multi-path lamp string, control circuit is obtained according to sample circuit
The work way of LED light string sends out the first pwm control signal to the first driving circuit, and output is reduced to each paths of LEDs lamp to adjust
The total current of string avoids each paths of LEDs lamp string from causing to flow through asking for its each LED light string branch current overcurrent due to certain paths of LEDs open circuit
Topic.The actual current value that control circuit acquires each paths of LEDs lamp string according to sample circuit sends out the second pwm control signal to the second drive
Dynamic circuit, to adjust the electric current of each paths of LEDs lamp string so that the electric current of each paths of LEDs lamp string can dynamic regulation, holding flows.Its
Middle control circuit is integrated in TV hardware circuits so that TV hardware circuits can efficiently realize LED sharing controls.Without existing
Have and frequently sent in technology in drive signal and enabling signal to the multichannel brightness adjustment control chip being set to outside TV hardware modules,
Reduce multichannel brightness adjustment control chip in the prior art, reduces cost.And working as has LED multi-path lamp string to carry out expansion connection
When, the expansion of pin need to be only carried out to control circuit, improve the compatibility of LED parallel current-equalizing circuits, solve existing multichannel
The inconvenient problem of LED sharing controls.
It should be appreciated that each section of the utility model can be realized with hardware, software, firmware or combination thereof.
In the above embodiment, the software or firmware that can in memory and by suitable instruction execution system be executed with storage are come real
It is existing.It, and in another embodiment, can be in following technology well known in the art for example, if realized with hardware
Any one or their combination are realized：Discrete logic with the logic gates for realizing logic function to data-signal
Circuit, the application-specific integrated circuit with suitable combinational logic gate circuit, programmable gate array (PGA), field-programmable gate array
It arranges (FPGA) etc..
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show
The description of example " or " some examples " etc. means specific features, structure, material or spy described in conjunction with this embodiment or example
Point is contained at least one embodiment or example of the utility model.In the present specification, to the schematic table of above-mentioned term
It states and may not refer to the same embodiment or example.Moreover, particular features, structures, materials, or characteristics described can be
It can be combined in any suitable manner in any one or more embodiments or example.
Above-described embodiments merely represent several embodiments of the utility model, the description thereof is more specific and detailed,
But it should not be understood as limiting the scope of the patent of the utility model.It should be pointed out that for the common of this field
For technical staff, without departing from the concept of the premise utility, various modifications and improvements can be made, these all belong to
In the scope of protection of the utility model.Therefore, the protection domain of the utility model patent should be determined by the appended claims.
Claims (9)
1. a kind of LED parallel current-equalizing circuits, including power supply circuit and LED multi-path lamp string, per road described in LED light string can connect difference
The LED light of quantity, which is characterized in that the LED parallel current-equalizing circuits further include control circuit, driving circuit and sample circuit；
The sample circuit is connect with the LED light string and the control circuit respectively, for acquiring LED light string described in each road
Actual current value, and the actual current value is sent to the control circuit；
The control circuit is connect with the power supply circuit, the sample circuit and the driving circuit respectively, for according to each
The actual current value of LED light string described in road sends pwm control signal to the driving circuit；
The driving circuit is connect with LED light string described in the power supply circuit, the control circuit and each road respectively, is used for root
The pwm control signal sent out according to the control circuit is received, control flow through the total current of LED light string described in each road and
The electric current of LED light string branch described in each road, the electric current to flow through LED light string described in each road remain unchanged.
2. LED parallel current-equalizing circuits according to claim 1, which is characterized in that the control circuit includes the first control
Circuit and second control circuit, the driving circuit include the first driving circuit and the second driving circuit,
The first control circuit is determined according to the current value for getting LED light string described in the collected every road of the sample circuit
The way for the LED light string that works, and it is true according to the load current value of the way of the work LED light string and the work LED light string
Surely the first pwm control signal is sent out to the driving circuit, so that first driving circuit control flows through LED light described in each road
The total current of string；
The second control circuit is used for defeated according to the current value for the LED light string that works described in each road and load current value adjustment
Go out to the duty ratio of the second pwm control signal of the driving circuit, so that second driving circuit drives work described in each road
The current value made in LED light string is equal with the load current value.
3. LED parallel current-equalizing circuits according to claim 2, which is characterized in that the power supply circuit includes that exchange inputs
Power supply, the filter circuit being connect with the alternating current input power supplying and the circuit of reversed excitation being connect with the filter circuit；
The circuit of reversed excitation include flyback primary circuit, the flyback transformer being connect with the flyback primary circuit, respectively with institute
State the constant current-supplying circuit and constant pressure power supply circuit of flyback transformer connection；
The flyback transformer is made of primary coil, the first secondary coil and the second secondary coil, the flyback primary circuit
Connect respectively with one end of the primary coil and the filter circuit, the other end of the primary coil also with the first field-effect
Pipe connects；First secondary coil is connect with the constant current-supplying circuit, for exporting constant current；Described second secondary sideline
Circle is connect with the constant pressure power supply circuit, for exporting constant voltage.
4. LED parallel current-equalizing circuits according to claim 3, which is characterized in that the both ends of the primary coil respectively with
The flyback primary circuit is connected with the drain electrode of first field-effect tube, the source electrode and first resistor of first field-effect tube
The grid of connection, first field-effect tube connects a pwm signal, for being exported according to the Duty ratio control of the pwm signal
To the energy of first secondary coil and second secondary coil；
The constant current-supplying circuit includes the first diode, the first capacitance and constant current inductance, the both ends of first secondary coil
Respectively with the anode of first diode and connect, the both ends of first capacitance are born with first diode respectively
Pole and ground connect, and the cathode of first diode also connect with one end of the constant current inductance, the constant current inductance it is another
End is the constant current output end of the constant current-supplying circuit；
The constant pressure power supply circuit includes the second diode and the second capacitance, the both ends of second secondary coil respectively with it is described
The positive and ground connection of second diode, the both ends of second capacitance connect with the cathode of second diode and ground respectively
It connects, the other end of second diode is the constant pressure output end of the constant pressure power supply circuit.
5. LED parallel current-equalizing circuits according to claim 4, which is characterized in that first driving circuit includes and institute
The first triode for stating the connection of constant pressure power supply circuit, the second triode being connect respectively with first triode and the second electricity
Resistance, the zener diode that is connect respectively with the second resistance and the second field-effect tube, and respectively with second field-effect
The 3rd resistor and third diode of pipe connection；
Wherein, the collector of first triode is connect with the constant pressure output end, the emitter point of first triode
Do not connect with one end of the emitter of second triode and the second resistance, the base stage of first triode respectively with
The base stage of second triode is connected with the first control circuit, the collector of second triode respectively with digitally
With the anode connection of the zener diode, the other end of the second resistance respectively with the cathode of the zener diode and institute
The grid connection of the second field-effect tube is stated, the source electrode of second field-effect tube is connect with one end of the 3rd resistor, described
The drain electrode of second field-effect tube is connect with the anode of the constant current output end and the third diode respectively, the three or two pole
The cathode of pipe is connect with LED light string described in each road respectively, one third capacitance of the third diodes in parallel.
6. LED parallel current-equalizing circuits according to claim 5, which is characterized in that second driving circuit includes one the
The grid of three field-effect tube, the third field-effect tube is connect with the second control circuit, the source of the third field-effect tube
Pole is grounded, and the drain electrode of the third field-effect tube is connected with the corresponding LED light string, and second driving circuit is according to
The electricity of the duty cycle adjustment LED light string within each period for second pwm control signal that second control circuit is sent out
Flow the length of make-and-break time.
7. LED parallel current-equalizing circuits according to claim 1, which is characterized in that the sample circuit is put including an operation
It is big device, the first input circuit being connect with the normal phase input end of the operational amplifier, defeated with the negative of the operational amplifier
The second input circuit for entering end connection, the benefit connected between the negative-phase input of the operational amplifier and its output end respectively
The clamp circuit repaid circuit and connect with the output end of the operational amplifier, second input circuit and the LED light
Series winding connects, and the clamp circuit is connect with the control circuit, and the sample circuit is used to flow through the electric current of the LED light string
It is exported to the control circuit after differential amplification and amplitude limit clamper.
8. LED parallel current-equalizing circuits according to claim 7, which is characterized in that
First input circuit includes the 4th resistance being connect respectively with the normal phase input end of the operational amplifier, the 4th electricity
Appearance and the 5th resistance；
Second input circuit include the 6th resistance being connect with the negative-phase input of the operational amplifier and with it is described
6th resistance connects the 7th resistance, the 8th resistance and the 9th resistance, one end that the 6th resistance is connect with the 7th resistance
Also it is connect with the LED light string；
The compensation circuit includes the tenth resistance and the 5th capacitance, wherein the tenth resistance and the 5th capacitance are connected in parallel
Between the negative-phase input and output end of the operational amplifier；
The clamp circuit includes the eleventh resistor being connect with the output end of the operational amplifier, respectively with the described 11st
The 6th capacitance and double diode of resistance connection, the plus earth of a diode of the double diode, another diode
Cathode connect with power pins, for clamping down on output signal between the voltage that 0V and the power pins are provided.
9. LED parallel current-equalizing circuits according to claim 6, which is characterized in that first field-effect tube, described second
Field-effect tube, the third field-effect tube are the enhanced metal-oxide-semiconductor of N-channel.
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| CN201721551685.4U CN207612441U (en) | 2017-11-17 | 2017-11-17 | LED parallel current-equalizing circuits |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111565494A (en) * | 2020-07-10 | 2020-08-21 | 深圳市全智芯科技有限公司 | LED lamp control circuit and baton |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111565494A (en) * | 2020-07-10 | 2020-08-21 | 深圳市全智芯科技有限公司 | LED lamp control circuit and baton |
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