CN207625830U - Constant current control circuit and backlight constant current control system - Google Patents
Constant current control circuit and backlight constant current control system Download PDFInfo
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- CN207625830U CN207625830U CN201721305240.8U CN201721305240U CN207625830U CN 207625830 U CN207625830 U CN 207625830U CN 201721305240 U CN201721305240 U CN 201721305240U CN 207625830 U CN207625830 U CN 207625830U
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Abstract
The utility model discloses a constant current control circuit, the circuit includes power conversion circuit, sampling circuit, controller, drive circuit, first voltage input end, second voltage input end; the input end of the power conversion circuit is connected with the first voltage input end; the power output end of the power conversion circuit is used for being connected with the input end of a load; the input end of the sampling circuit is connected with the output end of the load; the output end of the sampling circuit is connected with the sampling signal input end of the controller; the input end of the driving circuit is connected with the driving signal output end of the controller; the power supply end of the driving circuit is connected with the second voltage input end; and the output end of the driving circuit is connected with the power control end of the power conversion circuit. The utility model discloses effective reduce cost has improved whole constant current control circuit's stability. Correspondingly, the utility model also provides a constant current control system is shaded.
Description
Technical field
The utility model is related to current constant control technical fields, and in particular to a kind of constant-current control circuit and backlight current constant control
System.
Background technology
Common constant-current control circuit, as shown in Figure 1, be mainly made of hardware module and constant current output module etc.,
Middle constant current output module is to control output by one piece of external current constant control chip, and the current constant control chip is using in itself
The module set completes the runnings such as sampling, protection, driving to load.But if needing to carry out some complicated behaviour to load
Make, then needs to change drive signal by the controller in hardware module, the drive signal after change is then sent to perseverance
Flow control chip, and then make current constant control chip that corresponding action be taken to change the output to load.In hardware module
Controller is the control of single thread for current constant control chip, is only responsible for transmitting a drive signal, and cannot effectively be supervised
Whether protection, sampling, the driving etc. of control constant current part are completed, this causes the reliability of entire constant-current control circuit not high.In addition,
Relatively low to the utilization rate of the controller in hardware module in this system, controller in hardware module itself is a high property
The controller that can, have I/O mouthfuls of multiplexing can also be by adding one other than the task that itself need to be completed on its periphery
A little interlock circuits complete the task of control output.And at the same time using two pieces of functionally similar control chips but also entire permanent
The cost of flow control circuit is more expensive.
Utility model content
The purpose of this utility model is to provide a kind of constant-current control circuit and backlight Constant Current Control System, by hardware
Some interlock circuits are added to replace current constant control chip in the periphery of the controller of module, it is no longer necessary to independent current constant control core
Piece reduces cost.In addition, the running that the controller of hardware module is sampled by itself, protected, driven, effectively improves
The stability of entire constant-current control circuit.
In order to achieve the above object, the utility model embodiment provides a kind of constant-current control circuit, including power conversion electricity
Road, sample circuit, controller, driving circuit, first voltage input terminal, second voltage input terminal；
The input terminal of the power conversion circuit is connect with the first voltage input terminal；The work(of the power conversion circuit
Rate output end with the input terminal of load for connecting；The input terminal of the sample circuit is used to connect with the output end of the load
It connects；The output end of the sample circuit is connect with the sampled signal input of the controller；The input terminal of the driving circuit
It is connect with the driving signal output end of the controller；The power end of the driving circuit connects with the second voltage input terminal
It connects；The output end of the driving circuit is connect with the power control end of the power conversion circuit.
In a kind of optional embodiment, the power conversion circuit includes the first diode, inductance, field-effect tube；
The first end of the inductance is connect with the first voltage input terminal；The second end of the inductance and first field-effect tube
Drain electrode, the anode connection of first diode；The cathode of first diode is connect with the input terminal of the load, described
Power take-off of the cathode of first diode as the power conversion circuit；The grid of first field-effect tube with it is described
The output end of driving circuit connects, the power control end of the grid of first field-effect tube as the power conversion circuit；
The source electrode of first field-effect tube is grounded, and the source electrode of first field-effect tube is defeated as the electric current of the power conversion circuit
Outlet.
In a kind of optional embodiment, the constant-current control circuit further includes protection circuit, the protection circuit
Input terminal is connect with the current output terminal of the power conversion circuit；The guarantor of the output end and the controller of the protection circuit
Protect signal input part connection.
In a kind of optional embodiment, the sample circuit includes first resistor, second resistance, 3rd resistor,
Four resistance, the first capacitance, the first operational amplifier；
The first resistor be connected to the in-phase input end of the differential operational amplifier and the load output end it
Between；The second resistance is in parallel with the output end of the load；The 3rd resistor is connected to first operational amplifier
Between inverting input and signal ground；The output end of first operational amplifier passes through the 4th resistance and sampling electricity
The output end on road connects；Inverting input and first operation of first capacitance connection in first operational amplifier
Between the output end of amplifier.
In a kind of optional embodiment, the sample circuit further include the 5th resistance, the 6th resistance, the second capacitance,
Third capacitance；
5th resistance is in parallel with first capacitance；6th resistance is connected to first operational amplifier
Between in-phase input end and signal ground；Second capacitance and the 6th resistor coupled in parallel；The first end of the third capacitance with
4th resistance is connected with the tie point of the output end of the sample circuit；The second end of the third capacitance is grounded.
In a kind of optional embodiment, the sample circuit further includes the second diode and third diode；It is described
The plus earth of second diode；The cathode of second diode is connect with the output end of the sample circuit；The third
The anode of diode is connect with the output end of the sample circuit；The cathode of the third diode and the first external power supply connect
It connects.
In a kind of optional embodiment, the driving circuit includes push-pull circuit, the 7th resistance；
The push-pull circuit includes the first triode and the second triode, the emitter of first triode and described the
The emitter of two triodes is connected, and the cobasis of the push-pull circuit is extremely connect with the input terminal of the driving circuit；It is described
The collector of first triode is connect with the second voltage input terminal；The grounded collector of second triode；Described
The first end of seven resistance is connect with the first transistor emitter with the tie point of the emitter of second triode；Described 7th
The second end of resistance is connect with the output end of the driving circuit.
In a kind of optional embodiment, the protection circuit includes prime zoom comparison circuit and rear class light-coupled isolation
Circuit；
The prime zoom comparison circuit includes the 8th resistance, the 9th resistance, the tenth resistance, the 4th capacitance, the second operation
Amplifier, comparator；8th resistance is connected to the in-phase input end of the second operational amplifier and the power conversion
Between the current output terminal of circuit；The output end of the second operational amplifier passes through the 9th resistance and the comparator
Inverting input connects；Tenth resistance is connected between the in-phase input end and signal ground of the second operational amplifier；
The output end of inverting input and the second operational amplifier of 4th capacitance connection in the second operational amplifier
Between；The in-phase input end of the comparator is connect with first external power supply；The output end of the comparator is that short circuit is anti-
Feedback signal end；The positive power source terminal of the comparator is connect with the second external power supply；The negative power end of the comparator is grounded；
The rear class optical coupling isolation circuit includes photoelectrical coupler, thirteenth resistor, the 14th resistance；The photoelectric coupling
Device includes first input end, the second input terminal, the first output end, second output terminal；The wherein described first input end and described the
Two external power supplys connect；Second input terminal is connect with the output end of the comparator；First output end is divided into two-way,
It is connect all the way with first external power supply by the thirteenth resistor；Another way by the 14th resistance with it is described after
The output end connection of grade optical coupling isolation circuit.
In a kind of optional embodiment, the prime zoom comparison circuit further includes eleventh resistor, the 12nd electricity
Resistance, the 5th capacitance, the 6th capacitance；The eleventh resistor is in parallel with the 4th capacitance；The twelfth resistor is connected to institute
It states between the in-phase input end of second operational amplifier and signal ground；5th capacitance is in parallel with the twelfth resistor；Institute
The first end for stating the 6th capacitance is connect with the tie point of the 9th resistance and the inverting input of the comparator；Described 6th
The second end of capacitance is grounded；
The rear class optical coupling isolation circuit further includes the 15th resistance, the 7th capacitance；First output end passes through described
15th resistance is connect with second external power supply；The first end of 7th capacitance and the rear class optical coupling isolation circuit
Output end is connected；The second end of 7th capacitance is grounded；The second output terminal ground connection.
In order to reach above-mentioned identical purpose, the utility model additionally provides a kind of backlight Constant Current Control System, including opens
Powered-down source circuit, LED backlight and above-mentioned constant-current control circuit；The switching power circuit have first voltage output end with
Second voltage output end；The first voltage output end is connect with the first voltage input terminal in the constant-current control circuit；Institute
Second voltage output end is stated to connect with the second voltage input terminal in the constant-current control circuit；The input terminal of the LED backlight
It is connect with the power take-off of the power conversion circuit in the constant-current control circuit；The output end of the LED backlight with it is described
The input terminal of sample circuit in constant-current control circuit connects.
Compared with the prior art, a kind of advantageous effect of constant-current control circuit provided by the utility model is：The perseverance
Flow control circuit includes first voltage input terminal, second voltage input terminal, power conversion circuit, sample circuit, controller, driving
Circuit；The input terminal of the power conversion circuit is connect with the first voltage input terminal；The power of the power conversion circuit
Output end with the input terminal of load for connecting；The input terminal of the sample circuit with the output end of the load for connecting；
The output end of the sample circuit is connect with the sampled signal input of the controller；The input terminal of the driving circuit and institute
State the driving signal output end connection of controller；The power end of the driving circuit is connect with the second voltage input terminal；Institute
The output end for stating driving circuit is connect with the power control end of the power conversion circuit.By above structure, in hardware mould
Some interlock circuits are added to replace current constant control chip, to no longer need independent current constant control in the periphery of the controller of block
Chip reduces cost.In addition, the running that the controller of hardware module is sampled by itself, protected, driven, effectively carries
The high stability of entire constant-current control circuit.
Description of the drawings
Fig. 1 is a kind of circuit theory schematic diagram for constant-current control circuit that the prior art provides；
Fig. 2 is a kind of circuit theory schematic diagram for constant-current control circuit that the utility model embodiment one provides；
Fig. 3 is a kind of circuit theory schematic diagram for preferred constant-current control circuit that the utility model embodiment two provides；
Fig. 4 is the structural representation of the power conversion circuit in the constant-current control circuit that the utility model embodiment two provides
Figure；
Fig. 5 is the structural representation of the sample circuit in a kind of constant-current control circuit that the utility model embodiment two provides
Figure；
Fig. 6 is the structural representation of the driving circuit in a kind of constant-current control circuit that the utility model embodiment two provides
Figure；
Fig. 7 is the prime amplification in the protection circuit in a kind of constant-current control circuit that the utility model embodiment two provides
The structural schematic diagram of comparison circuit；
Fig. 8 is the rear class optocoupler in the protection circuit in a kind of constant-current control circuit that the utility model embodiment two provides
The structural schematic diagram of isolation circuit；
Fig. 9 is a kind of circuit theory schematic diagram for backlight Constant Current Control System that the utility model embodiment two provides.
Specific implementation mode
The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model
Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole
Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without creative efforts
The every other embodiment obtained, shall fall within the protection scope of the present invention.
Referring to Fig. 2, a kind of circuit theory of its constant-current control circuit that be the utility model embodiment one provided is shown
It is intended to, the constant-current control circuit 1 includes power conversion circuit 11, sample circuit 12, controller 13, driving circuit 14, first
Voltage input end Vin, second voltage input terminal Vdd；The input terminal of the power conversion circuit 11 is inputted with the first voltage
Hold Vin connections；The power take-off of the power conversion circuit 11 with the input terminal Vout of load for connecting；The sampling electricity
The input terminal on road 12 with the output end S1 of the load for connecting；The output end S2 of the sample circuit 12 and the controller
13 sampled signal input connection；The driving signal output end of the input terminal S3 and the controller 13 of the driving circuit 14
Connection；The power end of the driving circuit 14 is connect with the second voltage input terminal Vdd；The output end of the driving circuit 14
S4 is connect with the power control end of the power conversion circuit 11.
The operation principle of the utility model embodiment one is as follows：
The sample circuit 12 acquires the output current signal of the power conversion circuit 11 by the load, and should
Current signal is sent to the controller 13, and after the controller 13 gets current signal, which is carried out PID
Operation is controlled, determines and update the PWM duty cycle signal to be exported, and the PWM duty cycle signal is sent to the driving electricity
Road 14, the driving circuit 14 control the output current of the power conversion circuit 11 to be adjusted according to PWM duty cycle signal
System, to realize the control of constant current.
Referring to Fig. 3, it is a kind of circuit for preferred constant-current control circuit that the utility model embodiment two is provided
Principle schematic.
It is understood that in order to preferably be protected to the constant-current control circuit 1, relative to a upper embodiment one
The constant-current control circuit 1 of offer, the constant-current control circuit that the present embodiment two provides further include protection circuit 15, the protection circuit
15 input terminal is connect with the current output terminal S5 of the power conversion circuit 11；The output end S8 of the protection circuit 15 and institute
State the protection signal input terminal connection of controller 13.
It is one kind that the utility model embodiment two is provided please refer to Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, wherein Fig. 4
The structural schematic diagram of power conversion circuit in constant-current control circuit；Fig. 5 is one kind that the utility model embodiment two is provided
The structural schematic diagram of sample circuit in constant-current control circuit；Fig. 6 is a kind of constant current that the utility model embodiment two is provided
The structural schematic diagram of driving circuit in control circuit；Fig. 7 is a kind of preferred perseverance that the utility model embodiment two is provided
The structural schematic diagram of the prime zoom comparison circuit in protection circuit in flow control circuit；Fig. 8 is the utility model embodiment
The structural schematic diagram of the rear class optical coupling isolation circuit in protection circuit in a kind of two preferred constant-current control circuits provided；
Fig. 9 is a kind of circuit theory schematic diagram for backlight Constant Current Control System that the utility model embodiment two provides.
In the present embodiment, the power conversion circuit 11 includes the first diode D1, inductance L, field-effect tube Q1；It is described
The first end of inductance L is connect with the first voltage input terminal Vin；The second end of the inductance L and first field-effect tube
The draining of Q1, the connection of the anode of the first diode D1；The input terminal of the cathode and the load of the first diode D1
Vout connections, the power take-off of the cathode of the first diode D1 as the power conversion circuit 11；Described first
The grid of effect pipe D1 is connect with the output end S4 of the driving circuit 14, described in the grid conduct of the first field-effect tube Q1
The power control end of power conversion circuit 11；The source electrode of the first field-effect tube Q1 is grounded, the first field-effect tube Q1's
Current output terminal S5 of the source electrode as the power conversion circuit 11.
In a kind of optional embodiment, the constant-current control circuit further includes protection circuit 15, the protection circuit
15 input terminal S5 is connect with the current output terminal of the power conversion circuit 11；The output end S6 of the protection circuit 15 and institute
State the protection signal input terminal connection of controller 13.
In a kind of optional embodiment, the sample circuit 12 includes first resistor R1, second resistance R2, third electricity
Hinder R3, the 4th resistance R4, the first capacitance C1, the first operational amplifier A 1；
The first resistor R1 is connected to the output end of the in-phase input end and the load of the differential operational amplifier
Between S1；The second resistance R2 is in parallel with the output end S1 of the load；The second resistance R2 mainly by multiple resistance simultaneously
Connection is constituted；The 3rd resistor R3 is connected between the inverting input and signal ground of first operational amplifier A 1；It is described
The output end of first operational amplifier A 1 is connect by the 4th resistance R4 with the output end S2 of the sample circuit 12；It is described
First capacitance C1 is connected to the output of the inverting input and first operational amplifier A 1 of first operational amplifier A 1
Between end.Wherein, the second resistance R2 is accurate sampling resistor, is entered back into for current signal to be converted into voltage signal
It to differential amplifier circuit, is finally improved, forms the digital signal that the controller 13 can identify；The first capacitance C1
An integrating circuit is constituted with the 3rd resistor R3, the relationship of input and output is to carry out an integral to input voltage signal
Collected pulse signal is converted into step signal by operation, so that controller 13 can preferably determine collected voltage
Signal magnitude has the function of keeping signal.
In a kind of optional embodiment, the sample circuit 12 further includes the 5th resistance R5, the 6th resistance R6, second
Capacitance C2, third capacitance C3；
The 5th resistance R5 is in parallel with the first capacitance C1；The 6th resistance R6 is connected to first operation and puts
Between the in-phase input end and signal ground of big device A1；The second capacitance C2 is in parallel with the 6th resistance R6；The third electricity
The first end for holding C3 is connect with the tie point of the 4th resistance R4 and the output end S2 of the sample circuit 12；The third electricity
Hold the second end ground connection of C3.Wherein, the second capacitance C2 and the 6th resistance R6 constitutes low-pass filter；5th electricity
The effect for hindering R5 is that low frequency signal gain is excessive in order to prevent；The third capacitance C3 is for filtering.
In a kind of optional embodiment, the sample circuit 12 further includes the second diode D2 and third diode
D3；The plus earth of the second diode D2；The output end of the cathode and the sample circuit 12 of the second diode D2
S2 connections；The anode of the third diode D3 is connect with the output end S2 of the sample circuit 12；The third diode D3
Cathode connect with the first external power supply V1.Wherein, the first external power supply V1 is the 3.3V that the controller 13 is taken over
Pull-up circuit；The second diode D2 and third diode D3 plays clamping action, and the control is entered for limiting
Voltage signal in device 13 not less than 0V and is not higher than 3.3V.
The operation principle of the sample circuit 12 in the utility model embodiment is as follows：
The sample circuit 12 is actually an A/D converter, for converting analog signals into the controller 13
The circuit for the digital signal that can be identified.The voltage value of the second voltage input passes through the first resistor as the reference voltage
Signal is passed to institute after the low-pass filter that R1, second resistance R2 and the second capacitance C2 and the 6th resistance R6 are constituted
State the first operational amplifier A 1.First operational amplifier A 1 other than playing the role of differential amplification, can also by signal into
Row amplitude limit.The output of first operational amplifier A 1 is terminated with the 3.3V pull-up circuits that the controller 13 is taken over, and can incite somebody to action
Output signal is controlled in 0-3.3V, and the A/D interfaces of the controller 13 is allow effectively to identify.
In a kind of optional embodiment, the driving circuit 14 includes push-pull circuit, the 7th resistance R7；
The push-pull circuit include the first triode Q2 and the second triode Q3, the emitter of the first triode Q2 with
The emitter of the second triode Q3 is connected, the input terminal of the cobasis of the push-pull circuit extremely with the driving circuit 14
S3 connections；The collector of the first triode Q2 is connect with the second voltage input terminal Vdd；The second triode Q3's
Grounded collector；The transmitting of the first end and the first triode Q2 emitters and the second triode Q3 of the 7th resistance R7
The tie point of pole connects；The second end of the 7th resistance R7 is connect with the output end S4 of the driving circuit 14；Wherein, described
Second voltage input terminal Vdd is+12V DC voltage.
In a kind of optional embodiment, the driving circuit 14 further includes the 4th diode D4, the four or two pole
The first end of pipe D4 is connect with the tie point of the 7th resistance R7 and the output end S4 of the driving circuit 14；Described 4th 2
The second end of pole pipe D4 is grounded；Wherein, the 4th diode D4 is used for voltage stabilizing.
The operation principle of the driving circuit 14 in the utility model embodiment is as follows：
The push-pull circuit is increased the power of drive waveforms using the voltage that the second voltage input terminal Vdd is inputted
Greatly, the smaller drive waveforms that the controller 13 exports are made to zoom into the higher drive waveforms of driving capability, described in realizing
Controller 13 is by the first field-effect tube Q1 in the power conversion circuit 11 to the drive control of the load.
In a kind of optional embodiment, the protection circuit 15 include prime zoom comparison circuit and rear class optocoupler every
From circuit；
The prime zoom comparison circuit include the 8th resistance R8, the 9th resistance R9, the tenth resistance R10, the 4th capacitance C4,
Second operational amplifier A2, comparator A3；The 8th resistance R8 is connected to the homophase input of the second operational amplifier A2
Between end and the current output terminal S5 of the power conversion circuit 11；The output end of the second operational amplifier A2 passes through described
9th resistance R9 is connect with the inverting input of the comparator A3；The tenth resistance R10 is connected to second operation and puts
Between the in-phase input end and signal ground of big device A2；The 4th capacitance C4 is connected to the reverse phase of the second operational amplifier A2
Between input terminal and the output end of the second operational amplifier A2；Outside the in-phase input end of the comparator A3 and described first
Connect power supply V1 connections；The output end of the comparator A3 is short-circuit feedback signal end S6；The positive power source terminal of the comparator A3 with
Second external power supply V2 connections；The negative power end of the comparator A3 is grounded；Wherein, the second external power supply V2 is that+5V is straight
Galvanic electricity pressure；The 4th capacitance C4 and the tenth resistance R10 constitutes an integrating circuit, and the relationship of input and output is to defeated
Enter voltage signal and carry out an integral operation, collected pulse signal is converted into step signal, so that controller 13 can be with
It preferably determines collected voltage signal size, has the function of keeping signal；
The rear class optical coupling isolation circuit includes photoelectrical coupler OC, thirteenth resistor R13, the 14th resistance R14；It is described
Photoelectrical coupler includes first input end, the second input terminal, the first output end, second output terminal；The wherein described first input end
It is connect with the second external power supply V2；The second input terminal S7 is connect with the output end S6 of the comparator A3；Described
One output end is divided into two-way, is connect all the way with the first external power supply V1 by the thirteenth resistor R13；Another way passes through
The 14th resistance R14 is connect with the output end of the rear class optical coupling isolation circuit.
In a kind of optional embodiment, the prime zoom comparison circuit further includes eleventh resistor R11, the 12nd
Resistance R12, the 5th capacitance C5, the 6th capacitance C6；The eleventh resistor R11 is in parallel with the 4th capacitance C4；Described tenth
Two resistance R12 are connected between the in-phase input end and signal ground of the second operational amplifier A2；The 5th capacitance C5 with
The twelfth resistor R12 is in parallel；；The first end of the 6th capacitance C6 is with the 9th resistance R9's and comparator A3
The tie point of inverting input connects；The second end of the 6th capacitance C6 is grounded；Wherein, the 5th capacitance C5 and described the
12 resistance R12 constitute low-pass filter；The effect of the eleventh resistor R11 is that low frequency signal gain is excessive in order to prevent；
The 6th capacitance C6 is for filtering；
The rear class optical coupling isolation circuit further includes the 15th resistance R15, the 7th capacitance C7；First output end passes through
The 15th resistance R15 is connect with the second external power supply V2；The first end of the 7th capacitance C7 and the rear class light
The output end S8 of coupling isolation circuit is connected；Output of the output end of the rear class optical coupling isolation circuit as the protection circuit
End；The second end of the 7th capacitance C7 is grounded；The second output terminal ground connection.Wherein, the 15th resistance R15 is for limiting
Stream；The 7th capacitance C7 and the 14th resistance R14 forms low-pass filter.
The operation principle of the protection circuit 15 in the utility model embodiment is as follows：
The prime zoom comparison circuit part：The output of the second operational amplifier A2 is the anti-of the comparator A3
To input terminal；First external power supply+the 3.3V enters the positive input of the comparator A3 as the reference voltage.Work as electricity
When occurring over-current phenomenon avoidance in road, the current output terminal of the power conversion circuit 11 will produce a bigger voltage difference, warp
Crossing the second operational amplifier A2 can enter in the comparator A3, and the comparator A3 reverse input ends can be higher than it just
To the reference voltage of input terminal to make the comparator A3 export low level；If not occurring over-current phenomenon avoidance in circuit, the ratio
High level is exported compared with device A3.
Rear class optical coupling isolation circuit part：
The photoelectrical coupler OC includes photodiode and optocoupler triode；When the output of the comparator A3 is high electricity
Usually, i.e., overcurrent does not occur for circuit, and the photodiode anode and cathode are high level, does not trigger three pole of the optocoupler
Pipe, the high level that the optical coupling isolator output is 3.3V.When the output of the comparator A3, i.e., overcurrent, institute occur for circuit
It states light emitting diode and triggers the optocoupler triode, make the optical coupling isolator OC move ground to and export to be low level, to institute
The signal can be received to close PWM wave output by stating controller 13, stopped normal work, generated alarm.
Meanwhile the utility model additionally provides a kind of backlight Constant Current Control System, as shown in figure 9, including switch power supply
Road 2, LED backlight 3 and above-mentioned constant-current control circuit 1；The switching power circuit 2 has first voltage output end and second
Voltage output end；The first voltage output end is connect with the first voltage input terminal in the constant-current control circuit；Described
Two voltage output ends are connect with the second voltage input terminal in the constant-current control circuit；The input terminal of the LED backlight 3 and institute
State the power take-off connection of the power conversion circuit 11 in constant-current control circuit；The output end of the LED backlight 3 and the perseverance
The input terminal of sample circuit 12 in flow control circuit connects.
Compared with the prior art, a kind of advantageous effect of constant-current control circuit provided by the utility model is：The perseverance
Flow control circuit include first voltage input terminal Vin, second voltage input terminal Vdd, power conversion circuit 11, sample circuit 12,
Controller 13, driving circuit 14；The input terminal of the power conversion circuit 11 is connect with the first voltage input terminal Vin；Institute
The power take-off of power conversion circuit 11 is stated for being connect with the input terminal Vout of load；The input terminal of the sample circuit 12
It is connect for the output end S1 with the load；The sampled signal of the output end S2 and the controller 13 of the sample circuit 12
Input terminal connects；The input terminal S3 of the driving circuit 14 is connect with the driving signal output end of the controller 13；The drive
The power end of dynamic circuit 14 is connect with the second voltage input terminal Vdd；The output end S4 of the driving circuit 14 and the work(
The power control end of rate translation circuit 11 connects.By above structure, in the periphery addition one of the controller 13 of hardware module
A little interlock circuits replace current constant control chip, to no longer need independent current constant control chip, reduce cost.In addition, hard
The running that the controller 13 of part module is sampled by itself, protected, driven, is effectively improved entire constant-current control circuit
Stability.
It is preferred embodiments of the present invention above, it is noted that for those skilled in the art
For, without departing from the principle of this utility model, several improvements and modifications can also be made, these improvements and modifications
It is considered as the scope of protection of the utility model.
Claims (10)
1. a kind of constant-current control circuit, which is characterized in that including power conversion circuit, sample circuit, controller, driving circuit,
First voltage input terminal, second voltage input terminal；
The input terminal of the power conversion circuit is connect with the first voltage input terminal；The power of the power conversion circuit is defeated
Outlet with the input terminal of load for connecting；The input terminal of the sample circuit with the output end of the load for connecting；Institute
The output end for stating sample circuit is connect with the sampled signal input of the controller；The input terminal of the driving circuit with it is described
The driving signal output end of controller connects；The power end of the driving circuit is connect with the second voltage input terminal；It is described
The output end of driving circuit is connect with the power control end of the power conversion circuit.
2. constant-current control circuit as described in claim 1, which is characterized in that the power conversion circuit includes the one or two pole
Pipe, inductance, the first field-effect tube；The first end of the inductance is connect with the first voltage input terminal；The second of the inductance
It holds and the draining of first field-effect tube, the anode of first diode is connect；The cathode of first diode and institute
State the input terminal connection of load, the power take-off of the cathode of first diode as the power conversion circuit；It is described
The grid of first field-effect tube is connect with the output end of the driving circuit, and the grid of first field-effect tube is as the work(
The power control end of rate translation circuit；The source electrode of first field-effect tube is grounded, the source electrode conduct of first field-effect tube
The current output terminal of the power conversion circuit.
3. constant-current control circuit as claimed in claim 2, which is characterized in that the constant-current control circuit further includes protection electricity
The input terminal on road, the protection circuit is connect with the current output terminal of the power conversion circuit；The output of the protection circuit
End is connect with the protection signal input terminal of the controller.
4. constant-current control circuit as described in claim 1, which is characterized in that the sample circuit includes first resistor, second
Resistance, 3rd resistor, the 4th resistance, the first capacitance, the first operational amplifier；
The first resistor is connected between the in-phase input end and the output end of the load of first operational amplifier；Institute
It is in parallel with the output end of the load to state second resistance；The reverse phase that the 3rd resistor is connected to first operational amplifier is defeated
Enter between end and signal ground；The output end of first operational amplifier is defeated by the 4th resistance and the sample circuit
Outlet connects；Inverting input and first operational amplifier of first capacitance connection in first operational amplifier
Output end between.
5. constant-current control circuit as claimed in claim 4, which is characterized in that the sample circuit further includes the 5th resistance,
Six resistance, the second capacitance, third capacitance；
5th resistance is in parallel with first capacitance；6th resistance is connected to the same phase of first operational amplifier
Between input terminal and signal ground；Second capacitance and the 6th resistor coupled in parallel；The first end of the third capacitance with it is described
4th resistance is connected with the tie point of the output end of the sample circuit；The second end of the third capacitance is grounded.
6. constant-current control circuit as claimed in claim 5, which is characterized in that the sample circuit further include the second diode with
Third diode；The plus earth of second diode；The output of the cathode and the sample circuit of second diode
End connection；The anode of the third diode is connect with the output end of the sample circuit；The cathode of the third diode with
First external power supply connects.
7. constant-current control circuit as described in claim 1, which is characterized in that the driving circuit includes push-pull circuit, the 7th
Resistance；
The push-pull circuit includes the first triode and the second triode, the emitter of first triode and the described 2nd 3
The emitter of pole pipe is connected, and the cobasis of the push-pull circuit is extremely connect with the input terminal of the driving circuit；Described first
The collector of triode is connect with the second voltage input terminal；The grounded collector of second triode；7th electricity
The first end of resistance is connect with the first transistor emitter with the tie point of the emitter of second triode；7th resistance
Second end connect with the output end of the driving circuit.
8. constant-current control circuit as claimed in claim 3, which is characterized in that the protection circuit includes prime zoom comparison electricity
Road and rear class optical coupling isolation circuit；
The prime zoom comparison circuit includes the 8th resistance, the 9th resistance, the tenth resistance, the 4th capacitance, the second operation amplifier
Device, comparator；8th resistance is connected to the in-phase input end of the second operational amplifier and the power conversion circuit
Current output terminal between；The reverse phase that the output end of the second operational amplifier passes through the 9th resistance and the comparator
Input terminal connects；Tenth resistance is connected between the in-phase input end and signal ground of the second operational amplifier；It is described
4th capacitance connection is between the inverting input and the output end of the second operational amplifier of the second operational amplifier；
The in-phase input end of the comparator is connect with the first external power supply；The output end of the comparator is short-circuit feedback signal end；
The positive power source terminal of the comparator is connect with the second external power supply；The negative power end of the comparator is grounded；
The rear class optical coupling isolation circuit includes photoelectrical coupler, thirteenth resistor, the 14th resistance；The photoelectrical coupler packet
Include first input end, the second input terminal, the first output end, second output terminal；Outside the wherein described first input end and described second
Connect power supply connection；Second input terminal is connect with the output end of the comparator；First output end is divided into two-way, all the way
It is connect with first external power supply by the thirteenth resistor；Another way passes through the 14th resistance and the rear class light
The output end of coupling isolation circuit connects.
9. constant-current control circuit as claimed in claim 8, which is characterized in that the prime zoom comparison circuit further includes the tenth
One resistance, twelfth resistor, the 5th capacitance, the 6th capacitance；The eleventh resistor is in parallel with the 4th capacitance；Described tenth
Two resistance are connected between the in-phase input end and signal ground of the second operational amplifier；5th capacitance and the described tenth
Two resistor coupled in parallel；The tie point of the first end of 6th capacitance and the 9th resistance and the inverting input of the comparator
Connection；The second end of 6th capacitance is grounded；
The rear class optical coupling isolation circuit further includes the 15th resistance, the 7th capacitance；First output end passes through the described tenth
Five resistance are connect with second external power supply；The output of the first end and the rear class optical coupling isolation circuit of 7th capacitance
End is connected；The second end of 7th capacitance is grounded；The second output terminal ground connection.
10. a kind of backlight Constant Current Control System, which is characterized in that including switching power circuit, LED backlight and claim 1-
Constant-current control circuit in 9 any one claims；The switching power circuit has first voltage output end and the second electricity
Press output end；The first voltage output end is connect with the first voltage input terminal in the constant-current control circuit；Described second
Voltage output end is connect with the second voltage input terminal in the constant-current control circuit；The input terminal of the LED backlight with it is described
The power take-off of power conversion circuit in constant-current control circuit connects；The output end of the LED backlight and the constant current control
The input terminal of sample circuit in circuit processed connects.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721305240.8U CN207625830U (en) | 2017-10-10 | 2017-10-10 | Constant current control circuit and backlight constant current control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721305240.8U CN207625830U (en) | 2017-10-10 | 2017-10-10 | Constant current control circuit and backlight constant current control system |
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| Publication Number | Publication Date |
|---|---|
| CN207625830U true CN207625830U (en) | 2018-07-17 |
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ID=62825941
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721305240.8U Active CN207625830U (en) | 2017-10-10 | 2017-10-10 | Constant current control circuit and backlight constant current control system |
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| Country | Link |
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| CN (1) | CN207625830U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109219218A (en) * | 2018-11-05 | 2019-01-15 | 宝鸡文理学院 | A kind of colleges and universities' daylight light intelligent control system |
-
2017
- 2017-10-10 CN CN201721305240.8U patent/CN207625830U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109219218A (en) * | 2018-11-05 | 2019-01-15 | 宝鸡文理学院 | A kind of colleges and universities' daylight light intelligent control system |
| CN109219218B (en) * | 2018-11-05 | 2024-04-23 | 宝鸡文理学院 | College fluorescent lamp intelligent control system |
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