CN106604472A - Led drive circuit - Google Patents
Led drive circuit Download PDFInfo
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- CN106604472A CN106604472A CN201611270924.9A CN201611270924A CN106604472A CN 106604472 A CN106604472 A CN 106604472A CN 201611270924 A CN201611270924 A CN 201611270924A CN 106604472 A CN106604472 A CN 106604472A
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- resistance
- transistor
- interconnection
- drive circuit
- led drive
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
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- Circuit Arrangement For Electric Light Sources In General (AREA)
- Led Devices (AREA)
Abstract
The invention discloses an LED drive circuit realized by a UC3842 chip design; the LED drive circuit can realize constant current output, and has overvoltage protection, dimming and output current switching functions. The LED drive circuit is low in cost and strong in universality.
Description
Technical field
The present invention relates to field of LED drive technology, more particularly to a kind of LED drive circuit.
Background technology
UC3842 is that a kind of single-ended Switching Power Supply of conventional current mode controls integrated circuit, is mainly used in reverse excitation circuit
In.What the LED-backlit in LCD TV was commonly used is BOOST circuits, and for the needs of light modulation, the control integrated circuit of exploitation
All it is special, not only expensive, also no versatility, the integrated circuit of each producer's exploitation can not be exchanged, once and IC
Damage, it is difficult to buy this special integrated circuit.Therefore, factory and duration have been highly desirable to set using universal integrated circuit
Backlight LED that meter makes drives to be occurred.It is a kind of common on market and very cheap Switching Power Supply control in view of UC3842
Integrated circuit processed, and the performance of integrated circuits is stable, and function is very complete, and peripheral circuit is adapted to flexibly arrange in pairs or groups, therefore is set with this IC
Count a kind of LED to drive.
The content of the invention
The main object of the present invention is to provide a kind of LED drive circuit, it is intended to improve the versatility of the LED drive circuit.
For achieving the above object, LED drive circuit proposed by the present invention includes UC3842 chips, first resistor, second electric
Resistance, 3rd resistor, the 4th resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance,
It is 11 resistance, the 19th resistance, the first electric capacity, the second electric capacity, the first transistor, transistor seconds, third transistor, the 4th brilliant
Body pipe, the 5th transistor, the 6th transistor, power output circuit and auxiliary power circuit；The benchmark electricity of the UC3842 chips
The first end interconnection of presser feet, the first end, the first end of the tenth resistance and the 11st resistance of the 5th resistance, institute
The first end for stating the second end of the 5th resistance, the vibration foot of the UC3842 chips and first electric capacity is interconnected, and described first
The second end ground connection of electric capacity；Second end of the 11st resistance, the compensation foot of the UC3842 chips, second electric capacity
The input interconnection of first end, the input of the 6th transistor and the first transistor, the second of second electric capacity
End ground connection；The output head grounding of the first transistor, the controlled end of the first transistor, the second end of the first resistor
And the first end interconnection of the second resistance, the first end of the first resistor, the outfan of the power output circuit and treat
Drive the positive pole interconnection of LED lamp bar, the second end ground connection of the second resistance；The output head grounding of the 6th transistor, institute
State the input interconnection of the controlled end, the second end of the tenth resistance and the 5th transistor of the 6th transistor, described the
The output head grounding of five transistors, the controlled end of the 5th transistor are connected with the first end of the 9th resistance, and described
Second end of nine resistance is connected with the second end of the 6th resistance, and its connecting node is used to be input into dim signal, and the described 6th
The first end of resistance is connected with the controlled end of the 4th transistor, the output head grounding of the 4th transistor, and the described 4th
The input of transistor is connected with the second end of the 7th resistance, the first end and the third transistor of the 7th resistance
Controlled end connection, the outfan of the third transistor is connected with the first end of the 8th resistance, the third transistor
Input, the outfan of the auxiliary power circuit and the UC3842 chips supply pin interconnection；The third transistor
Outfan be connected with the first end of the 8th resistance, the second end of the 8th resistance is controlled with the transistor seconds
End connection, the input of the transistor seconds are connected with the negative pole of LED lamp bar to be driven；The outfan of transistor seconds,
The second end interconnection of the first end of three resistance and the 4th resistance, the second end ground connection of the 3rd resistor, the 4th resistance
First end is connected with the second end of the 19th resistance, the first end of the 19th resistance and the electricity of the UC3842 chips
Pressure feedback foot connection；The feedback end of the power output circuit is connected with the current sampling foot of the UC3842 chips, the electricity
The controlled end of source follower circuit is connected with the output pin of the UC3842 chips.
Preferably, the auxiliary power circuit includes the 12nd resistance, the 7th transistor and Zener diode, the described tenth
The input of the first end of two resistance and the 7th transistor is all connected with the first power supply, the second end of the 12nd resistance,
The negative electrode interconnection of the controlled end and the Zener diode of the 7th transistor, the plus earth of the Zener diode, institute
The outfan for stating the 7th transistor is the outfan of the auxiliary power circuit.
Preferably, the power output circuit include boosting unit, the 13rd resistance, the 14th resistance, the 15th resistance,
16th resistance, the 3rd electric capacity and the 8th transistor, the input connection input power of the boosting unit, the boosting unit
The first outfan be the power output circuit outfan, the second outfan of the boosting unit and the 8th crystal
The input connection of pipe, the controlled end of the 8th transistor are connected with the second end of the 16th resistance, and the described 16th
The first end of resistance is the controlled end of the power output circuit, the outfan of the 8th transistor, the 13rd resistance
The second end and the 14th resistance first end interconnection, the 14th resistance the second end ground connection, the described 13rd is electric
The first end interconnection of the first end of resistance, the first end of the 3rd electric capacity and the 15th resistance, its connecting node is described
The feedback end of power output circuit, the 3rd electric capacity the second end ground connection, the second end of the 15th resistance with it is described
The reference voltage foot connection of UC3842 chips.
Preferably, the LED drive circuit also includes the first diode, the anode of first diode, described
The input interconnection of the compensation foot and the first transistor of UC3842 chips, the negative electrode of first diode, the described 6th
The first end interconnection of the input of transistor, the second end of the 11st resistance and second electric capacity.
Preferably, the LED drive circuit also includes the second diode, the anode of second diode, the described tenth
The first end interconnection of the second end of one resistance and second electric capacity, the negative electrode of two diode, the 11st resistance
The reference voltage foot interconnection of first end and the UC3842 chips.
Preferably, the LED drive circuit also includes the 17th resistance, the 18th resistance and the 9th transistor, described the
Second end of 17 resistance is used to receive switch-over control signal, first end and the 9th transistor of the 17th resistance
Controlled end connects, the output head grounding of the 9th transistor, input and the 18th resistance of the 9th transistor
The connection of the second end, the of the first end of the 18th resistance, the second end of the 19th resistance and the 4th resistance
One end interconnects.
Preferably, the LED drive circuit also include the 20th resistance, the first end of the 20th resistance with it is described
The reference voltage foot connection of UC3842 chips, the second end of the 20th resistance, the first end of the 19th resistance and institute
State the Voltage Feedback foot interconnection of UC3842 chips.
Preferably, the LED drive circuit also includes the 21st resistance, the first end of the 21st resistance, institute
The second end of the 8th resistance and the controlled end interconnection of the transistor seconds are stated, it is the second end of the 21st resistance, described
The second end interconnection of the outfan of transistor seconds, the first end of the 3rd resistor and the 4th resistance.
Preferably, the LED drive circuit also include the 22nd resistance, the 4th electric capacity and the 5th electric capacity, the described 5th
The first end of electric capacity is connected with the compensation foot of the UC3842 chips, the second end of the 5th electric capacity, the 4th electric capacity
The first end interconnection of first end and the 22nd resistance, the second end of the 4th electric capacity, the 22nd resistance
The Voltage Feedback foot interconnection of the second end and the UC3842 chips.
Preferably, the UC3842 chips can also derive from cake core, improvement cake core or homologous series chip with which and replace
Generation.
This driving LED drive circuit is by increasing the electricity such as resistance, electric capacity and transistor on the basis of UC3842 chips
Sub- components and parts, realize the functions such as the constant current output of LED drive circuit, output over-voltage protection, light modulation, output current switching, energy
Enough meet the power demands of most of LED lamp bars.As this LED drive circuit is realized based on the design of UC3842 chips, and
UC3842 chips are that a kind of common on market and very cheap Switching Power Supply controls integrated circuit, and the performance of integrated circuits
Stable, function is very complete, and peripheral circuit is adapted to flexible.Therefore, corresponding, this LED drive circuit at least has highly versatile, cost
Low the characteristics of.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
Accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Structure according to these accompanying drawings obtains other accompanying drawings.
Fig. 1 is the electrical block diagram of one embodiment of LED drive circuit of the present invention.
Drawing reference numeral explanation：
The realization of the object of the invention, functional characteristics and advantage will be described further in conjunction with the embodiments referring to the drawings.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment a part of embodiment only of the invention, rather than the embodiment of whole.Base
Embodiment in the present invention, those of ordinary skill in the art obtained under the premise of creative work is not made it is all its
His embodiment, belongs to the scope of protection of the invention.
If it is to be appreciated that the directional instruction (such as up, down, left, right, before and after ...) of institute in the embodiment of the present invention,
It is only used for explaining in the relative position relation under a certain particular pose (as shown in drawings) between each part, motion conditions etc., such as
Really the particular pose changes, then directionality indicates also correspondingly to change therewith.
In addition, the description for being related to " first ", " second " etc. in the present invention is only used for describing purpose, and it is not intended that referring to
Show or imply its relative importance or the implicit quantity for indicating indicated technical characteristic.Thus, define " first ", "
Two " at least one this feature can be expressed or be implicitly included to feature.In addition, the technical scheme between each embodiment can
To be combined with each other, but must can be implemented as basis with those of ordinary skill in the art, when the combination of technical scheme occurs
It is conflicting or will be understood that the combination of this technical scheme is not present when cannot realize, also not in the protection model of application claims
Within enclosing.
The present invention proposes a kind of LED drive circuit, can realize constant current output, output over-voltage protection, light modulation, output current
The functions such as switching.Further, since the LED drive circuit is realized based on UC3842 chips U1 designs, and UC3842 chip U1 are one
On kind of market, common and very cheap Switching Power Supply controls integrated circuit, and the performance of integrated circuits is stable, and function is very complete,
Peripheral circuit is adapted to flexible.Therefore, it is corresponding, this LED drive circuit at least have highly versatile, low cost the characteristics of.Wherein,
UC3842 chips U1 can also be derived from cake core (such as, UC3843, UC3844, UC3845), be improved cake core (such as, with which
UC3842A, UC3843A, UC3845A) or homologous series chip (such as, UC1842, UC2842) replacement.Specifically, refer to
The description below.
In one embodiment, above-mentioned LED drive circuit includes UC3842 chip U1, first resistor R1, second resistance R2,
Three resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9,
Ten resistance R10, the 11st resistance R11, the 19th resistance R19, the first electric capacity C1, the second electric capacity C2, the first transistor Q1, second
Transistor Q2, third transistor Q3, the 4th transistor Q4, the 5th transistor Q5, the 6th transistor Q6, power output circuit 20 and
Auxiliary power circuit 10.
Wherein, the reference voltage foot VREF of UC3842 chips U1, the first end of the 5th resistance R5, the of the tenth resistance R10
The first end interconnection of one end and the 11st resistance R11, second end of the 5th resistance R5, the vibration foot RT/CT of UC3842 chip U1
And first electric capacity C1 first end interconnection, the first electric capacity C1 the second end ground connection；Second end of the 11st resistance R11, UC3842
The compensation foot COMP of chip U1, the first end of the second electric capacity C2, the input of the 6th transistor Q6 and the first transistor Q1's is defeated
Enter end interconnection, the second end ground connection of the second electric capacity C2；The output head grounding of the first transistor Q1, the first transistor Q1's are controlled
The first end interconnection of end, the second end of first resistor R1 and second resistance R2, the first end of first resistor R1, power output circuit
The positive pole interconnection of 20 outfan and LED lamp bar LB to be driven, the second end ground connection of second resistance R2；6th transistor Q6's is defeated
Go out end ground connection, the input of the controlled end, second end of the tenth resistance R10 and the 5th transistor Q5 of the 6th transistor Q6 is interconnected,
The output head grounding of the 5th transistor Q5, the controlled end of the 5th transistor Q5 are connected with the first end of the 9th resistance R9, and the 9th is electric
Second end of resistance R9 is connected with second end of the 6th resistance R6, and its connecting node is used to be input into dim signal DIM, the 6th resistance R6
First end be connected with the controlled end of the 4th transistor Q4, the output head grounding of the 4th transistor Q4, the 4th transistor Q4's are defeated
Enter end to be connected with second end of the 7th resistance R7, the first end of the 7th resistance R7 is connected with the controlled end of third transistor Q3, the
The outfan of three transistor Q3 is connected with the first end of the 8th resistance R8, the input of third transistor Q3, auxiliary power circuit
10 outfan and the supply pin VCC interconnection of UC3842 chip U1；The of the outfan of third transistor Q3 and the 8th resistance R8
One end connects, and second end of the 8th resistance R8 is connected with the controlled end of transistor seconds Q2, the input of transistor seconds Q2 and
The negative pole connection of LED lamp bar LB to be driven；The outfan of transistor seconds Q2, the first end of 3rd resistor R3 and the 4th resistance R4
The second end interconnection, 3rd resistor R3 the second end ground connection, the first end of the 4th resistance R4 and the second of the 19th resistance R19
End connection, the first end of the 19th resistance R19 are connected with the Voltage Feedback foot VFB of UC3842 chip U1；Power output circuit 20
Feedback end be connected with the current sampling foot Isense of UC3842 chip U1, the controlled end of power output circuit 20 and UC3842 cores
The output pin OUT connections of piece U1.
Here, 3rd resistor R3 and the 4th resistance R4, the 19th resistance R19 formation constant current feedback circuits (figure is not marked).
Specifically, the electric current for flowing through LED lamp bar LB forms sampled voltage at 3rd resistor R3 two ends, and passes through the 4th resistance R4, and the tenth
Nine resistance R19 feed back to the Voltage Feedback foot VFB of UC3842 chip U1.UC3842 chips U1 can be according to falling in its Voltage Feedback foot
The voltage swing of VFB is accordingly controlled to the electric current for flowing through LED lamp bar LB, permanent with the size of current for flowing through LED lamp bar LB
It is fixed.
First resistor R1, second resistance R2 and the first transistor Q1 form output overvoltage protection circuit (figure is not marked).Tool
Body ground, when the output voltage of power output circuit 20 is more than default threshold voltage, falls in the first end of second resistance R2
Cut-in voltage of the voltage more than the first transistor Q1, the first transistor Q1 conductings, falls in the compensation foot COMP of UC3842 chip U1
Voltage be pulled low, the output pin OUT of UC3842 chip U1 stops output, reaches the purpose of overvoltage protection.
6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the tenth resistance R10, transistor seconds Q2,
Third transistor Q3, the 4th transistor Q4, the 5th transistor Q5 and the 6th transistor Q6 composition light adjusting circuit (figure is not marked).Tool
Body ground, when dim signal DIM is high level, the 4th transistor Q4 conductings, the voltage of the controlled end of third transistor Q3 are drawn
Low, the voltage of the controlled end of transistor seconds Q2 is elevated, and transistor seconds Q2 conductings, LED drive circuit drive LED lamp bar LB
Work.At the same time, the 5th transistor Q5 conductings, the voltage of the 6th transistor Q6 controlled ends are pulled low, and the 6th transistor Q6 cuts
Only, therefore the voltage in the compensation foot COMP of UC3842 chip U1 that falls will not be pulled low, and LED drive circuit keeps power supply output.
When dim signal DIM is low level, the 4th transistor Q4 cut-offs, the cut-off of third transistor Q3, transistor seconds Q2 cut-offs,
The supply access of LED lamp bar LB is cut off.At the same time, the 5th transistor Q5 cut-offs, the 6th transistor Q6 conductings, UC3842 cores
The voltage of the compensation foot COMP of piece U1 is pulled low, and the output pin OUT of UC3842 chip U1 stops output, LED drive circuit cut-out
Power supply is exported.Adjust the dutycycle of dim signal DIM, it is possible to reach the purpose of light modulation.
It is preferred that above-mentioned auxiliary power circuit 10 includes the 12nd resistance R12, the 7th transistor Q7 and Zener diode
The input of the first end and the 7th transistor Q7 of DZ, the 12nd resistance R12 is all connected with the first power supply VCC, the 12nd resistance
The negative electrode interconnection at second end, the controlled end of the 7th transistor Q7 and Zener diode DZ of R12, the anode of Zener diode DZ connect
Ground, the outfan of the 7th transistor Q7 are the outfan of auxiliary power circuit 10.
It is appreciated that the voltage perseverance in 10 course of work of auxiliary power circuit, due to being added in Zener diode DZ two ends
Determine, and the pressure drop between the controlled end and outfan of the 7th transistor Q7 is fixed, therefore, 10 outfan pair of auxiliary power circuit
Ground voltage is also fixed.So, it is ensured that UC3842 chips U1 obtains stable supply voltage, relative to directly electric using first
Source VCC provides the scheme of supply voltage for UC3842 chip U1, enhances the reliability of LED drive circuit.
It is preferred that above-mentioned power output circuit 20 include boosting unit 21, the 13rd resistance R13, the 14th resistance R14,
15th resistance R15, the 16th resistance R16, the 3rd electric capacity C3 and the 8th transistor Q8, the input connection of boosting unit 21 are defeated
Enter power supply VI, the first outfan of boosting unit 21 is the outfan of power output circuit 20, and the second of boosting unit 21 exports
End is connected with the input of the 8th transistor Q8, and the controlled end of the 8th transistor Q8 is connected with second end of the 16th resistance R16,
Controlled end of the first end of the 16th resistance R16 for power output circuit 20, the outfan of the 8th transistor Q8, the 13rd resistance
Second end of R13 and the first end interconnection of the 14th resistance R14, the second end ground connection of the 14th resistance R14, the 13rd resistance
The first end interconnection of the first end of R13, the first end of the 3rd electric capacity C3 and the 15th resistance R15, its connecting node is that power supply is defeated
Go out the feedback end of circuit 20, second end of the 3rd electric capacity C3 is grounded, and second end of the 15th resistance R15 is with UC3842 chip U1's
Reference voltage foot VREF connects.
Here, boosting unit 21 can adopt BOOST Boost topology frameworks, it would however also be possible to employ other topological structures.
It is noted that in the LED drive circuit course of work, the compensation foot COMP of UC3842 chip U1 needs simultaneously
Receive the feedback signal of the feedback signal and light adjusting circuit of overvoltage crowbar.For the feedback for preventing overvoltage crowbar from exporting
The feedback signal that signal is exported with light adjusting circuit is interfered, and in the present embodiment, is also additionally arranged the first diode D1, specifically,
The input interconnection of the anode of the first diode D1, the compensation foot COMP and the first transistor Q1 of UC3842 chip U1, the one or two
The negative electrode of pole pipe D1, the input, second end of the 11st resistance R11 and the second electric capacity C2 of the 6th transistor Q6 first end it is mutual
Even.
Additionally, on above-mentioned UC3842 chips U1 during electricity, the second electric capacity C2 is charged by the 11st resistance R11, and
During UC3842 chip U1 power down, the second electric capacity C2 does not have discharge loop.Based on this, in the present embodiment, the two or two pole is also additionally arranged
Pipe D2, specifically, the first end interconnection of the anode, second end of the 11st resistance R11 and the second electric capacity C2 of the second diode D2,
The reference voltage foot VREF interconnection of the negative electrode, the first end of the 11st resistance R11 and UC3842 chip U1 of the second diode D2.
Further, in the present embodiment, LED drive circuit also includes the 17th resistance R17, the 18th resistance R18 and the
Nine transistor Q9, to realize the function of output current switching.Wherein, second end of the 17th resistance R17 is used to receive switching control
Signal 2D/3D processed, the first end of the 17th resistance R17 are connected with the controlled end of the 9th transistor Q9, and the 9th transistor Q9's is defeated
Go out end ground connection, the input of the 9th transistor Q9 is connected with second end of the 18th resistance R18, the first of the 18th resistance R18
The first end interconnection of end, second end of the 19th resistance R19 and the 4th resistance R4.
Specifically, when the switch-over control signal 2D/3D of input is low level, the 9th transistor Q9 cut-offs fall
The voltage of the Voltage Feedback foot VFB of UC3842 chip U1 is the voltage fallen in 3rd resistor R3 first end；When the switching control of input
Signal 2D/3D processed be high level when, the 9th transistor Q9 conducting, fall UC3842 chip U1 Voltage Feedback foot VFB voltage
The voltage for being the voltage that falls in 3rd resistor R3 first end Jing after the 4th resistance R4 and the 8th resistance R8 partial pressures.That is, working as
The switch-over control signal 2D/3D of input be low level when, it is desirable to fall 3rd resistor R3 first end voltage with fall
The voltage swing of the Voltage Feedback foot VFB of UC3842 chip U1 is equal, when the switch-over control signal 2D/3D of input is high level
When, it is desirable to the voltage in the first end of 3rd resistor R3 that falls be higher than fall UC3842 chip U1 Voltage Feedback foot VFB voltage.
Thus, when the switch-over control signal 2D/3D of input is low level, the electric current for flowing through LED lamp bar LB is relatively small；When input
When switch-over control signal 2D/3D is high level, the electric current for flowing through LED lamp bar LB is relatively large, i.e. switch-over control signal 2D/3D can
So that the different electric current of LED drive circuit switching output.
Further, in the present embodiment, LED drive circuit also includes electric for reducing the 20th of 3rd resistor R3 power consumption the
Resistance R20.Specifically, the first end of the 20th resistance R20 is connected with the reference voltage foot VREF of UC3842 chip U1, and the 20th is electric
The Voltage Feedback foot VFB interconnection at second end, the first end of the 19th resistance R19 and UC3842 chip U1 of resistance R20.
Further, in the present embodiment, LED drive circuit also includes the 21st of transistor seconds Q2 the electric for protecting
Resistance R21.Specifically, the controlled end of the first end, second end of the 8th resistance R8 and transistor seconds Q2 of the 21st resistance R21
Interconnection, second end of the 21st resistance R21, the outfan of transistor seconds Q2, the first end of 3rd resistor R3 and the 4th are electric
The second end interconnection of resistance R4.
Further, in the present embodiment, LED drive circuit is also included for anti-to the voltage of UC3842 chip U1 to being input into
The 22nd resistance R22, the 4th electric capacity C4 and the 5th electric capacity C5 that the feedback signal of feed pin VFB is corrected.Specifically, the 5th
The first end of electric capacity C5 is connected with the compensation foot COMP of UC3842 chip U1, second end of the 5th electric capacity C5, the 4th electric capacity C4
The first end interconnection of first end and the 22nd resistance R22, second end of the 4th electric capacity C4, the second of the 22nd resistance R22
The Voltage Feedback foot VFB interconnection of end and UC3842 chip U1.
Hereinafter, with reference to Fig. 1, illustrate the operation principle of LED drive circuit of the present invention：
This LED drive circuit controls the 8th transistor Q8 work by the output pin OUT of UC3842 chip U1, so as to realize
Constant current output.In the LED drive circuit course of work：
If the output voltage of power output circuit 20 is more than default threshold voltage, fall in the first end of second resistance R2
Voltage more than the first transistor Q1 cut-in voltage, the first transistor Q1 conducting, fall in the compensation foot of UC3842 chip U1
The voltage of COMP is pulled low, and the output pin OUT of UC3842 chip U1 stops output, reaches the purpose of overvoltage protection.
If the dim signal DIM of input is high level, the 4th transistor Q4 conductings, the controlled end of third transistor Q3
Voltage is pulled low, and the voltage of the controlled end of transistor seconds Q2 is elevated, and transistor seconds Q2 conductings, LED drive circuit drive
LED lamp bar LB works.At the same time, the 5th transistor Q5 conductings, the voltage of the 6th transistor Q6 controlled ends are pulled low, and the 6th is brilliant
Body pipe Q6 ends, and therefore the voltage in the compensation foot COMP of UC3842 chip U1 that falls will not be pulled low, and LED drive circuit keeps electric
Source exports.If the dim signal DIM of input is low level, the 4th transistor Q4 cut-offs, the cut-off of third transistor Q3, second is brilliant
Body pipe Q2 ends, and the supply access of LED lamp bar LB is cut off.At the same time, the 5th transistor Q5 cut-offs, the 6th transistor Q6 are led
Logical, the voltage of the compensation foot COMP of UC3842 chip U1 is pulled low, and the output pin OUT of UC3842 chip U1 stops output, and LED drives
Galvanic electricity road is cut off the electricity supply output.Adjust the dutycycle of dim signal DIM, it is possible to reach the purpose of light modulation.
If the switch-over control signal 2D/3D of input is low level, fall in the Voltage Feedback foot VFB of UC3842 chip U1
Voltage is the voltage fallen in 3rd resistor R3 first end；If the switch-over control signal 2D/3D of input is high level, fall
The voltage of the Voltage Feedback foot VFB of UC3842 chip U1 is the 4th resistance R4 of voltage Jing and fallen in 3rd resistor R3 first end
Voltage after 18 resistance R18 partial pressures.Adjust the switch-over control signal 2D/3D of input, so that it may so that LED drive circuit switching is defeated
Go out different electric currents.
The preferred embodiments of the present invention are the foregoing is only, the scope of the claims of the present invention is not thereby limited, it is every at this
Under the inventive concept of invention, the equivalent structure transformation made using description of the invention and accompanying drawing content, or directly/use indirectly
It is included in the scope of patent protection of the present invention in other related technical fields.
Claims (9)
1. a kind of LED drive circuit, it is characterised in that including UC3842 chips, first resistor, second resistance, 3rd resistor,
Four resistance, the 5th resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the tenth resistance, the 11st resistance, the tenth
Nine resistance, the first electric capacity, the second electric capacity, the first transistor, transistor seconds, third transistor, the 4th transistor, the 5th crystal
Pipe, the 6th transistor, power output circuit and auxiliary power circuit；
The reference voltage foot of the UC3842 chips, the first end of the 5th resistance, the first end of the tenth resistance and institute
State the first end interconnection of the 11st resistance, the second end of the 5th resistance, the vibration foot of the UC3842 chips and described the
The first end interconnection of one electric capacity, the second end ground connection of first electric capacity；Second end of the 11st resistance, the UC3842
The compensation foot of chip, the first end of second electric capacity, the input of the 6th transistor and the first transistor it is defeated
Enter end interconnection, the second end ground connection of second electric capacity；The output head grounding of the first transistor, the first transistor
The first end interconnection of controlled end, the second end of the first resistor and the second resistance, the first end of the first resistor, institute
State the positive pole interconnection of the outfan and LED lamp bar to be driven of power output circuit, the second end ground connection of the second resistance；It is described
The output head grounding of the 6th transistor, the controlled end of the 6th transistor, second end and the described 5th of the tenth resistance
The input interconnection of transistor, the output head grounding of the 5th transistor, the controlled end of the 5th transistor and described the
The first end connection of nine resistance, the second end of the 9th resistance are connected with the second end of the 6th resistance, its connecting node
For being input into dim signal, the first end of the 6th resistance is connected with the controlled end of the 4th transistor, and the described 4th is brilliant
The output head grounding of body pipe, the input of the 4th transistor are connected with the second end of the 7th resistance, and the described 7th is electric
The first end of resistance is connected with the controlled end of the third transistor, the outfan of the third transistor and the 8th resistance
First end connects, the input of the third transistor, the outfan of the auxiliary power circuit and the UC3842 chips
Supply pin is interconnected；The outfan of the third transistor is connected with the first end of the 8th resistance, and the of the 8th resistance
Two ends are connected with the controlled end of the transistor seconds, the negative pole of the input of the transistor seconds and LED lamp bar to be driven
Connection；The second end interconnection of the outfan of transistor seconds, the first end of 3rd resistor and the 4th resistance, the 3rd resistor
Second end is grounded, and the first end of the 4th resistance is connected with the second end of the 19th resistance, the 19th resistance
First end is connected with the Voltage Feedback foot of the UC3842 chips；The feedback end of the power output circuit and the UC3842 cores
The current sampling foot connection of piece, the controlled end of the power output circuit are connected with the output pin of the UC3842 chips.
2. LED drive circuit as claimed in claim 1, it is characterised in that the auxiliary power circuit include the 12nd resistance,
The input of the 7th transistor and Zener diode, the first end of the 12nd resistance and the 7th transistor is all connected with
One power supply, the negative electrode at second end, the controlled end of the 7th transistor and the Zener diode of the 12nd resistance are mutual
Even, the plus earth of the Zener diode, the outfan of the 7th transistor is the outfan of the auxiliary power circuit.
3. LED drive circuit as claimed in claim 1, it is characterised in that the power output circuit include boosting unit,
13 resistance, the 14th resistance, the 15th resistance, the 16th resistance, the 3rd electric capacity and the 8th transistor, the boosting unit
Input connects input power, and the first outfan of the boosting unit is the outfan of the power output circuit, the liter
Second outfan of pressure unit is connected with the input of the 8th transistor, the controlled end of the 8th transistor and described the
The second end connection of 16 resistance, the first end of the 16th resistance is the controlled end of the power output circuit, described the
The first end interconnection of the outfan of eight transistors, the second end of the 13rd resistance and the 14th resistance, the described tenth
The second end ground connection of four resistance, the first end of the 13rd resistance, the first end of the 3rd electric capacity and described 15th electric
The first end interconnection of resistance, its connecting node is the feedback end of the power output circuit, the second end ground connection of the 3rd electric capacity,
Second end of the 15th resistance is connected with the reference voltage foot of the UC3842 chips.
4. LED drive circuit as claimed in claim 1, it is characterised in that the LED drive circuit also includes the one or two pole
Pipe, the input interconnection of the anode of first diode, the compensation foot of the UC3842 chips and the first transistor, institute
State the negative electrode of the first diode, the input of the 6th transistor, the second end of the 11st resistance and described second electric
The first end interconnection of appearance.
5. LED drive circuit as claimed in claim 1, it is characterised in that the LED drive circuit also includes the two or two pole
Pipe, the first end interconnection of the anode of second diode, the second end of the 11st resistance and second electric capacity are described
The reference voltage foot interconnection of the negative electrode of two diodes, the first end of the 11st resistance and the UC3842 chips.
6. LED drive circuit as claimed in claim 1, it is characterised in that the LED drive circuit is also electric including the 17th
Resistance, the 18th resistance and the 9th transistor, the second end of the 17th resistance are used to receiving switch-over control signal, and the described tenth
The first end of seven resistance is connected with the controlled end of the 9th transistor, the output head grounding of the 9th transistor, and described
The input of nine transistors is connected with the second end of the 18th resistance, the first end of the 18th resistance, the described tenth
The first end interconnection of the second end of nine resistance and the 4th resistance.
7. LED drive circuit as claimed in claim 6, it is characterised in that the LED drive circuit is also electric including the 20th
Resistance, the first end of the 20th resistance is connected with the reference voltage foot of the UC3842 chips, and the of the 20th resistance
The Voltage Feedback foot interconnection at two ends, the first end of the 19th resistance and the UC3842 chips.
8. LED drive circuit as claimed in claim 1, it is characterised in that the LED drive circuit is also electric including the 21st
Resistance, the controlled end interconnection of the first end, the second end of the 8th resistance and the transistor seconds of the 21st resistance,
Second end of the 21st resistance, the outfan of the transistor seconds, the first end of the 3rd resistor and described
The second end interconnection of four resistance.
9. LED drive circuit as claimed in claim 1, it is characterised in that the LED drive circuit is also electric including the 22nd
Resistance, the 4th electric capacity and the 5th electric capacity, the first end of the 5th electric capacity are connected with the compensation foot of the UC3842 chips, and described the
The first end interconnection at the second end of five electric capacity, the first end of the 4th electric capacity and the 22nd resistance, the described 4th is electric
The Voltage Feedback foot interconnection at the second end, the second end of the 22nd resistance and the UC3842 chips that hold.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611270924.9A CN106604472B (en) | 2016-12-30 | 2016-12-30 | LED drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611270924.9A CN106604472B (en) | 2016-12-30 | 2016-12-30 | LED drive circuit |
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| Publication Number | Publication Date |
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| CN106604472A true CN106604472A (en) | 2017-04-26 |
| CN106604472B CN106604472B (en) | 2019-05-31 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201611270924.9A Active CN106604472B (en) | 2016-12-30 | 2016-12-30 | LED drive circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113608567A (en) * | 2021-08-04 | 2021-11-05 | 北京控制工程研究所 | UC 1843-based programmable constant current source system |
| DE102019117472B4 (en) | 2018-06-28 | 2023-06-22 | Ledvance Gmbh | Driver, method of controlling the driver, and lighting module |
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| CN205319949U (en) * | 2015-12-31 | 2016-06-15 | 重庆川仪速达机电有限公司 | Novel simple and easy switching power supply |
| CN105934044A (en) * | 2016-07-01 | 2016-09-07 | 成都白描网络科技有限公司 | Multi-way output voltage stabilized power supply for LED based on snubber circuit |
| CN106211421A (en) * | 2016-07-01 | 2016-12-07 | 成都白描网络科技有限公司 | A kind of LED multiple-channel output regulated power supply based on overvoltage crowbar |
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| CN201204722Y (en) * | 2007-12-28 | 2009-03-04 | 王元成 | Automatic light-adjusting LED illumination driver |
| CN201854484U (en) * | 2010-11-04 | 2011-06-01 | 新视野光电（郑州）有限公司 | High-power LED constant-current driving power circuit |
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| Publication number | Publication date |
|---|---|
| CN106604472B (en) | 2019-05-31 |
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