CN204482091U - A kind of former limit feedback LED drive circuit - Google Patents
A kind of former limit feedback LED drive circuit Download PDFInfo
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- CN204482091U CN204482091U CN201520163735.6U CN201520163735U CN204482091U CN 204482091 U CN204482091 U CN 204482091U CN 201520163735 U CN201520163735 U CN 201520163735U CN 204482091 U CN204482091 U CN 204482091U
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Abstract
The utility model discloses a kind of former limit feedback LED drive circuit, comprise alternating current input, rectifying and voltage-stabilizing module, snubber module, transformer, converter chip, first electric capacity, second electric capacity and the first diode, wherein, described converter chip produces power supply by Drain end, inner integrated primary current sampling resistor, by the gate leakage capacitance sampling time limit ON time of built-in power switching tube, described power switch pipe Single-Chip Integration, described conversion chip produces power supply by Drain end, without the need to auxiliary winding power, transformer is made only to need two windings, simplify transformer device structure, by the integrated primary current sampling resistor in inside, eliminate CS pin, by the gate leakage capacitance sampling time limit ON time of built-in power switching tube, without the need to auxiliary limit rectifier diode and divider resistance, power switch pipe Single-Chip Integration, decreases peripheral components significantly, reduces system bulk, reduces cost.
Description
Technical field
The utility model relates to switch power technology field, particularly one former limit feedback LED drive circuit.
Background technology
Along with people are to environmental protection, energy-conservation, efficient requirement, LED illumination was advanced by leaps and bounds recent years, achieved the development of great-leap-forward.Fig. 1 gives a kind of existing former limit feedback (PSR) LED drive chip and application circuit thereof.As shown in Figure 1, the alternating current of described former limit feedback LED drive power access 85V ~ 265V, described former limit feedback LED drive power comprises rectifier bridge 101, high-voltage capacitance C101, starting resistance R101, auxiliary limit rectifier diode D101, VCC electric capacity C102, auxiliary limit divider resistance R102 and R103, primary current sampling resistor R104, snubber circuit 102, transformer 103, output rectifying tube D102, output capacitance C103, LED load 104, and converter chip 105.Described converter chip 105 comprises five pins: VCC pin, GND pin, FB pin, CS pin and Drain pin.Wherein, export before setting up, line voltage is charged to VCC electric capacity C102 by starting resistance R101, completes the startup of converter chip 105; Export after setting up, by auxiliary winding Na to the VCC pin powered of converter chip 105; The CS pin of converter chip 105 is for primary current of sampling; The FB pin of converter chip 105 is for time limit ON time of sampling; The Drain pin of converter chip 105 is drain terminals of built-in Power MOS.Described built-in Power MOS, what adopt is dual chip packing forms, by low voltage control chip and superhigh pressure Power MOS discrete device, be encapsulated in inside same carrier, this just requires, encapsulation cavity is enough large, it is large that chip takies volume, add the volume of PCB version, and it is higher to encapsulate cavity price, adds the cost of system; Described transformer comprises former limit winding Np, auxiliary winding Na and secondary winding Ns tri-windings.Wherein the auxiliary winding Na of transformer is used for powering to converter chip 105 and indirectly detecting time limit Tons discharge time, for use in Systematical control and output LED current.Because transformer needs three windings, complex manufacturing technology, peripheral components is many, and cost is higher.
Thus prior art need to improve.
Utility model content
In view of above-mentioned the deficiencies in the prior art part, the purpose of this utility model is to provide a kind of former limit feedback LED drive circuit, simplify driving method and the corresponding time limit demagnetization method of sampling, decrease peripheral components quantity, simplify application circuit and transformer manufacturing technique, reduce system cost.
In order to achieve the above object, the utility model takes following technical scheme:
A kind of former limit feedback LED drive circuit, comprises alternating current input, the first electric capacity, the second electric capacity, the first diode;
There is the transformer of former limit winding and secondary winding;
Alternating current for inputting alternating current input carries out rectification and voltage stabilizing, and exports to the rectifying and voltage-stabilizing module of snubber module;
For absorbing the snubber module of the self-induced e.m.f of described former limit winding;
Be DC voltage by AC voltage transitions, and export the converter chip of constant current;
Described alternating current input is by rectifying and voltage-stabilizing model calling snubber module, one end of the former limit winding of described snubber model calling transformer, the other end of described former limit winding connects the Drain end of converter chip, the VCC end of described converter chip is by the first capacity earth, the GND of described converter chip holds ground connection, one end of described secondary winding connects the positive pole of the first diode, the negative pole of described first diode by the second capacity earth, also by LED group ground connection, the other end ground connection of described secondary winding;
Described converter chip produces power supply, inner integrated primary current sampling resistor by Drain end, by the gate leakage capacitance sampling time limit ON time of built-in power switching tube, and described power switch pipe Single-Chip Integration.
In described former limit feedback LED drive circuit, described converter chip comprises power switch pipe, source drive pipe, the first resistance, the second diode;
For generation of startup and the supply module of built-in power supply;
The biasing module started with supply module is fed back to for generation of reference voltage;
For detecting former limit peak current, keep the Cycle by Cycle current comparator module that the peak current of each cycle is constant;
Utilize the gate-drain parasitic capacitances of power switch pipe, indirectly the secondary limit ON time detecting module of sampling time limit ON time;
For coming control logic and driver module according to time limit ON time, thus control the constant-current control module of output current;
For carrying out logical operation, output drive signal controls the logical AND driver module of the turn-on and turn-off of power switch pipe and source drive pipe;
The input of described startup and supply module is that the Drain of converter chip holds, connect the drain electrode of power switch pipe, described startup is connected converter chip VCC with the output of supply module holds, also connect the input of biasing module, the output of described biasing module connects the first input end of Cycle by Cycle current comparator module, the output of described Cycle by Cycle current comparator module connects the first input end of logical AND driver module, first output of described logical AND driver module connects the grid of source drive pipe, the source electrode of described source drive pipe connects the second input of Cycle by Cycle current comparator module, also by the first grounding through resistance, the grid of described power switch pipe connects the second output of logical AND driver module, the input of secondary limit ON time detecting module, the output of described limit ON time detecting module connects the input of constant-current control module, the output of described constant-current control module connects the second input of logical AND driver module, the source electrode of described power switch pipe connects the drain electrode of source drive pipe and the positive pole of the second diode, and the negative pole of described second diode connects the output started with supply module.
In described former limit feedback LED drive circuit, first feedback signal output of described biasing module connects the first feedback signal input terminal started with supply module, second feedback signal output of biasing module connects the second feedback signal input terminal started with supply module, and the 3rd feedback signal output of biasing module connects the 3rd feedback signal input terminal started with supply module, described startup and supply module comprise unlatching comparator, turn off comparator, first threshold selects control switch, Second Threshold selects control switch, logic control element, second resistance, 3rd resistance, 4th resistance, discharge control switch pipe, high_voltage isolation pipe and charging control valve, described first threshold selects one end of control switch to be start the first feedback signal input terminal with supply module, connect the first feedback signal output of biasing module, described first threshold selects the other end of control switch to connect the normal phase input end opening comparator, described Second Threshold selects one end of control switch to be start the second feedback signal input terminal with supply module, connect the second feedback signal output of biasing module, described Second Threshold selects the other end of control switch to connect the normal phase input end opening comparator, the output of described unlatching comparator connects the first input end of logic control element, the normal phase input end of described shutoff comparator is start the 3rd feedback signal input terminal with supply module, connect the 3rd feedback signal output of biasing module, the output of described shutoff comparator connects the second input of logic control element, the output of described logic control element connects the grid of discharge control switch pipe, the source ground of described discharge control switch pipe, the drain electrode of described discharge control switch pipe connects the grid of charging control valve, also connect the source electrode of high_voltage isolation pipe and the drain electrode of charging control valve by the second resistance, the grounded-grid of described high_voltage isolation pipe, the drain electrode of described high_voltage isolation pipe is start the input with supply module, the source electrode of described charging control valve is start the output with supply module, connect one end of the 3rd resistance, the other end of described 3rd resistance connects the inverting input opening comparator and the inverting input turning off comparator, also by the 4th grounding through resistance.
In described former limit feedback LED drive circuit, first feedback signal output of described biasing module exports the first feedback voltage, second feedback signal output of described biasing module exports the second feedback voltage, 3rd feedback signal output of described biasing module exports the 3rd feedback voltage, described first feedback voltage is greater than the second feedback voltage, and described second feedback voltage is greater than the 3rd feedback voltage.
In the feedback LED drive circuit of described former limit, described logic control element comprises the first inverter, d type flip flop, the first NOR gate, the second NOR gate, the 3rd NOR gate and first or door, the input of described first inverter and the first input end of the first NOR gate are the first input end of logic control element, connect the output opening comparator, second input of described first NOR gate and the second input of the second NOR gate are the second input of logic control element, connect the output turning off comparator, the output of described first NOR gate connects the first input end of the 3rd NOR gate, the output of described 3rd NOR gate connects the first input end of the second NOR gate, the output of described second NOR gate connects the second input of the 3rd NOR gate and the R end of d type flip flop, the C end of described d type flip flop connects the first output of logical AND driver module, the D of described d type flip flop holds the output of connection first inverter, the Q of described d type flip flop holds the first input end of connection first or door, described first or the second input of door connect the first output of logical AND driver module, first or the output of door be the output of logic control element, connect the grid of discharge control switch pipe.
In described former limit feedback LED drive circuit, described time limit ON time detecting module comprises current source, first switching tube, second switch pipe, 3rd switching tube, 4th switching tube, 5th switching tube, 6th switching tube, 7th switching tube, 8th switching tube, Schmidt trigger, second inverter, 3rd inverter, 4th inverter, four nor gate, 5th NOR gate, two inputs or door and three input NOR gate, also comprise high level conducting, low level turns off, the first switch controlled by the output end signal of three input NOR gate and high level conducting, low level turns off, by two input or door output end signal control second switch, the source electrode of described first switching tube connects the output started with supply module, and the drain electrode of described first switching tube is time input of limit ON time detecting module, the grid connecting power switch pipe, the drain electrode of second switch pipe, the grid of the 3rd switching tube, the grid of the 4th switching tube and one end of the first switch, the grid of described second switch pipe connects the first output of logical AND driver module, the source electrode of described second switch pipe connects the drain electrode of the 3rd switching tube, the source electrode of described 3rd switching tube connects the source electrode of the 4th switching tube and the negative pole of current source, the drain electrode of described 4th switching tube connects the source electrode of the 5th switching tube, and the grid of described 5th switching tube connects the first output of logical AND driver module, the positive pole of described current source connects the grid of the drain electrode of the 6th switching tube, the grid of the 6th switching tube, the grid of the 7th switching tube and the 8th switching tube, the source ground of described 6th switching tube, the drain electrode of described 7th switching tube connect the drain electrode of the 5th switching tube, Schmidt trigger input, also by second switch ground connection, the source ground of described 7th switching tube, the drain electrode of described 8th switching tube connects the other end of the first switch, the source ground of described 8th switching tube, the output of described Schmidt trigger connects the input of the second inverter, the output of described second inverter connects the first input end of four nor gate, the output of described four nor gate connects the first input end of the 5th NOR gate, second input of described 5th NOR gate connects the first output of logical AND driver module and the first input end of two inputs or door, the output of described 5th NOR gate connects the second input of four nor gate, second input of two inputs or door and the first input end of three input NOR gate, the output of described two inputs or door connects the input of the 3rd inverter, the output of described 3rd inverter connects the grid of the first switching tube, second input of described three input NOR gate connects the first output of logical AND driver module, 3rd input of described three input NOR gate connects the output of the 4th inverter, and the output of described three input NOR gate is time output of limit ON time detecting module, connects the input of constant-current control module, the input of described 4th inverter is Enable Pin, normal work time be high level.
In described former limit feedback LED drive circuit, described first switching tube, second switch pipe, the 3rd switching tube, the 4th switching tube and the 5th switching tube are P channel MOS tube; Described 6th switching tube, the 7th switching tube and the 8th switching tube are N-channel MOS pipe.
In described former limit feedback LED drive circuit, the 3rd electric capacity that described rectifying and voltage-stabilizing module comprises rectifier bridge and is connected in parallel with rectifier bridge.
In described former limit feedback LED drive circuit, described snubber module comprises the 5th resistance, the 4th electric capacity and the 3rd diode, described alternating current input is by one end of rectifying and voltage-stabilizing model calling the 5th resistance, one end of the 4th electric capacity and one end of transformer primary side winding, described 5th resistance and the other end of the 4th electric capacity are all connected the negative pole of the 3rd diode, and the positive pole of described 3rd diode connects the other end of former limit winding and the Drain end of converter chip.
In described former limit feedback LED drive circuit, described power switch pipe is 700V extra high tension power switching tube.
Compared to prior art, the former limit feedback LED drive circuit that the utility model provides, comprises a converter chip, described conversion chip produces power supply by Drain end, without the need to auxiliary winding power, make transformer only need two windings, simplify transformer device structure; By the integrated primary current sampling resistor in inside, eliminate CS pin; By the gate leakage capacitance sampling time limit ON time of built-in power switching tube, without the need to auxiliary limit rectifier diode and divider resistance; Power switch pipe Single-Chip Integration, decreases peripheral components significantly, reduces system bulk, reduces cost.
Accompanying drawing explanation
Fig. 1 is existing former limit feedback (PSR) LED drive chip and application circuit thereof.
The circuit diagram of the former limit feedback LED drive circuit that Fig. 2 provides for the utility model.
The structured flowchart of the converter chip of the former limit feedback LED drive circuit that Fig. 3 provides for the utility model.
In the former limit feedback LED drive circuit that Fig. 4 provides for the utility model, the startup of converter chip and the structured flowchart of supply module.
Fig. 5 feeds back in LED drive circuit for the former limit that the utility model provides, and starts the circuit diagram with the logic control element of supply module.
Fig. 6 feeds back in LED drive circuit for the former limit that the utility model provides, and starts the oscillogram with the signal of supply module input and output.
In the former limit feedback LED drive circuit that Fig. 7 provides for the utility model, the circuit diagram of secondary limit ON time detecting module.
Embodiment
The utility model provides a kind of former limit feedback LED drive circuit, and its conversion chip produces power supply, without the need to auxiliary winding power by Drain end; The power switch pipe Single-Chip Integration of conversion chip, while improving integrated level, reduces the requirement to encapsulation cavity volume; By by built-in for former limit sampling resistor, eliminate CS pin.
For making the purpose of this utility model, technical scheme and effect clearly, clearly, referring to the accompanying drawing embodiment that develops simultaneously, the utility model is further described.Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.
Refer to Fig. 2, the former limit feedback LED drive circuit that the utility model provides, comprises alternating current input J1, rectifying and voltage-stabilizing module 10, snubber module 20, transformer 30, converter chip U1, the first electric capacity C1, the second electric capacity C2 and the first diode D1.
Wherein, described rectifying and voltage-stabilizing module 10 carries out rectification and voltage stabilizing for the alternating current inputted alternating current input J1, and exports to snubber module 20.The 3rd electric capacity C3 that described rectifying and voltage-stabilizing module 10 comprises rectifier bridge 110 and is connected in parallel with rectifier bridge 110.Described alternating current input J1 is connected snubber module 20 by rectifier bridge 110 with the 3rd electric capacity C3.The positive pole of described 3rd electric capacity C3 connects output and the snubber module 20 of rectifier bridge 110, the minus earth of described 3rd electric capacity C3.Described 3rd electric capacity C3 is high-voltage electrolytic capacitor.
Described snubber module 20 is for absorbing the self-induced e.m.f of described former limit winding Np.
Described transformer 30 has former limit winding Np and secondary winding Ns.Only adopt two windings, simplify the manufacturing process flow of transformer 30, provide cost savings.
It is DC voltage that described converter chip U1 is used for AC voltage transitions, and exports constant current.
Described alternating current input J1 connects snubber module 20 by rectifying and voltage-stabilizing module 10, one end of the former limit winding Np of described snubber module 20 connection transformer 30, the other end of described former limit winding Np connects the Drain end of converter chip U1, the VCC end of described converter chip U1 is by the first electric capacity C1 ground connection, the GND of described converter chip U1 holds ground connection, one end of described secondary winding Ns connects the positive pole of the first diode D1, the negative pole of described first diode D1 is by the second electric capacity C2 ground connection, also by LED group 40 ground connection, the other end ground connection of described secondary winding Ns.
Described converter chip U1 produces power supply, inner integrated primary current sampling resistor by Drain end, by the gate leakage capacitance sampling time limit ON time of built-in power switching tube, and described power switch pipe Single-Chip Integration.
Described converter chip U1 adopts 700V superhigh pressure technique, by power switch pipe Single-Chip Integration, while improving integrated level, reduces the requirement to encapsulation cavity volume; By by built-in for former limit sampling resistor, eliminate CS pin; Indirectly detect the erasing time by the parasitic gate leakage capacitance of built-in power pipe, eliminate FB pin; By the combination of above technology, make chip only need three pins, TO-92 can be adopted to encapsulate, and packaging cost is low.
See also Fig. 3, described converter chip U1 comprises power switch pipe Q1, source drive pipe Q2, the first resistance R1, the second diode D2, starts and supply module 510, biasing module 520, Cycle by Cycle current comparator module 530, secondary limit ON time detecting module 550, constant-current control module 560 and logical AND driver module 540.
Wherein, start and supply module 510, for generation of built-in power supply, power to the modules of converter chip U1 inside (except other modules started and except supply module 510 in converter chip U1).
Biasing module 520, feeds back to for generation of reference voltage and starts and supply module 510, and is the module generation bias current in converter chip U1 except logical AND driver module 540.
Cycle by Cycle current comparator module 530, for detecting former limit peak current, keeps the peak current of each cycle constant.
Secondary limit ON time detecting module 550, utilizes the gate-drain parasitic capacitances Cgd of power switch pipe Q1, indirectly sampling time limit ON time Tons.
Constant-current control module 560, for coming control logic and driver module according to time limit ON time, thus the output current of control transformer 30.
Logical AND driver module 540, for carrying out logical operation, output drive signal controls the turn-on and turn-off of power switch pipe Q1 and source drive pipe Q2.
The input of described startup and supply module 510 is that the Drain of converter chip U1 holds, connect the drain electrode of power switch pipe Q1, described startup is connected converter chip U1 VCC with the output of supply module 210 holds, also connect the input of biasing module 520, the output of described biasing module 520 connects the first input end 1 of Cycle by Cycle current comparator module 530, the output of described Cycle by Cycle current comparator module 530 connects the first input end 1 ' of logical AND driver module 540, first output 1 ' of described logical AND driver module 540 ' connect the grid of source drive pipe Q2, the source electrode of described source drive pipe Q2 connects the second input 2 of Cycle by Cycle current comparator module 530, also by the first resistance R1 ground connection, the grid of described power switch pipe Q1 connects the second output 2 ' of logical AND driver module 540 ', the input of secondary limit ON time detecting module 550, the output of described limit ON time detecting module 550 connects the input of constant-current control module 560, the output of described constant-current control module 560 connects the second input 2 ' of logical AND driver module 540, the source electrode of described power switch pipe Q1 connects the drain electrode of source drive pipe Q2 and the positive pole of the second diode D2, the negative pole of described second diode D2 connects the output (namely the VCC of converter chip U1 holds) started with supply module 510.
Described Cycle by Cycle current comparator module 530 comprises a Cycle by Cycle current comparator OCP, the inverting input of described Cycle by Cycle current comparator OCP is the first input end 1 of Cycle by Cycle current comparator module 530, the normal phase input end of described Cycle by Cycle current comparator OCP is the second input of Cycle by Cycle current comparator module 530, and the output of described Cycle by Cycle current comparator OCP is the output of Cycle by Cycle current comparator module 530.
Described power switch pipe Q1 is 700V extra high tension power switching tube, and is N-channel MOS pipe.Described source drive pipe Q2 is 5V low pressure source electrode driving N channel MOS tube.Described first resistance R1 is primary current sampling resistor, and described second diode D2 plays clamping action.First output 1 ' of described logical AND driver module ' output signal for low level time, source drive pipe Q2 turns off, power switch pipe Q1 is still in conducting state, the drain terminal of source drive pipe Q2 can be driven high, exceed its source and drain withstand voltage, the effect of the second diode D2 be namely in order to by the drain terminal voltage clamping of source drive pipe Q2 at internal electric source, prevent it from puncturing.
Refer to Fig. 3 and Fig. 4, first feedback signal output a of described biasing module 520 connects the first feedback signal input terminal a ' started with supply module 510, second feedback signal output b of biasing module 520 connects the second feedback signal input terminal b ' started with supply module 510, and the 3rd feedback signal output c of biasing module 520 connects the 3rd feedback signal input terminal c ' started with supply module 510, described startup and supply module 510 comprise opens comparator U2, turn off comparator U3, first threshold selects control switch K1, Second Threshold selects control switch K2, logic control element 511, second resistance R2, 3rd resistance R3, 4th resistance R4, discharge control switch pipe Q3, high_voltage isolation pipe Q5 and charging control valve Q4, described first threshold selects one end of control switch K1 to be start the first feedback signal input terminal a ' with supply module 510, connect the first feedback signal output a of biasing module, described first threshold selects the other end of control switch K1 to connect the normal phase input end opening comparator U2, described Second Threshold selects one end of control switch K2 to be start the second feedback signal input terminal b ' with supply module 510, connect the second feedback signal output b of biasing module, described Second Threshold selects the other end of control switch K2 to connect the normal phase input end opening comparator U2, the output of described unlatching comparator U2 connects the first input end d of logic control element 511, the normal phase input end of described shutoff comparator U3 is start the 3rd feedback signal input terminal c ' with supply module 510, connect the 3rd feedback signal output c of biasing module 520, the output of described shutoff comparator U3 connects the second input e of logic control element 511, the output of described logic control element 511 connects the grid of discharge control switch pipe Q3, the source ground of described discharge control switch pipe Q3, the drain electrode of described discharge control switch pipe Q3 connects the grid of charging control valve Q4, also connect the source electrode of high_voltage isolation pipe Q5 and the drain electrode of charging control valve Q4 by the second resistance, the grounded-grid of described high_voltage isolation pipe Q5, the drain electrode of described high_voltage isolation pipe Q5 is start the input with supply module 510, the source electrode of described charging control valve Q4 is start the output with supply module 510, connect one end of the 3rd resistance R3, the other end of described 3rd resistance R3 connects the inverting input opening comparator U2 and the inverting input turning off comparator U3, also by the 4th resistance R4 ground connection.
Wherein, described high_voltage isolation pipe Q5 is JFET, and its pinch-off threshold is at more than 7V, and namely during its source voltage <7V, high_voltage isolation pipe Q5 is in conducting state, can think switching tube.Discharge control switch pipe Q3 and charging control valve Q4 is the high voltage bearing asymmetric NMOS of drain terminal, the specifically withstand voltage pinch-off threshold depending on high_voltage isolation pipe Q5.First feedback signal output a of described biasing module 520 exports the first feedback voltage V 1, second feedback signal output b of described biasing module 520 exports the second feedback voltage V 2,3rd feedback signal output c of described biasing module 520 exports the 3rd feedback voltage V 3, described first feedback voltage V 1 is greater than the second feedback voltage V 2, and described second feedback voltage V 2 is greater than the 3rd feedback voltage V 3.Namely described V1, V2 and V3 are all reference voltages, and have V1>V2>V3, and V1 and V2 is close, only have ten millivolts of ranks, and object is the ripple of the VCC end reducing converter chip U1.
Refer to Fig. 4 and Fig. 5, described logic control element 511 comprises the first inverter U4, d type flip flop U8, the first NOR gate U5, the second NOR gate U6, the 3rd NOR gate U7 and first or door U9, the described input of the first inverter U4 and the first input end f of the first NOR gate U5 are the first input end d of logic control element 511, connect the output opening comparator U2, the second input e that the second input f ' of described first NOR gate U5 and the second input g ' of the second NOR gate U6 is logic control element 511, connect the output turning off comparator U3, the output of described first NOR gate U5 connects the first input end h of the 3rd NOR gate U7, the output of described 3rd NOR gate U7 connects the first input end g of the second NOR gate U6, the output of described second NOR gate U6 connects the second input h ' of the 3rd NOR gate U7 and the R end of d type flip flop U8, the C end of described d type flip flop U8 connects the first output 1 ' of logical AND driver module 540 ', the D of described d type flip flop U8 holds the output of connection first inverter U4, the Q of described d type flip flop holds the first input end I of connection first or door U9, described first or the second input I ' of door U9 connect the first output 1 ' of logical AND driver module 540 ', first or the output of door U9 be the output of logic control element 511, connect the grid of discharge control switch pipe Q3.Wherein, described first threshold selects control switch K1 and Second Threshold to select the switch that control switch K2 is high level conducting, low level turns off.Described first threshold selects control switch K1 by the control of opening the signal ON that comparator U2 output exports; The control of the signal ON_hys that described Second Threshold selects control switch K2 to export by the first inverter U4 output; Namely first threshold selects control switch K1 and Second Threshold to select the disconnected state of leading of control switch K2 to be contrary all the time.
Start with supply module 510 startup stage, the lower <V3 of VCC terminal voltage, the signal OFF turning off comparator U3 output is high level, the signal EN that then the second NOR gate U6 exports is low level, d type flip flop U8 is exported and resets, first output 1 ' of logical AND driver module 540 ' the signal PWM that exports is low level, therefore logic control element 511 exports as low level, and discharge control switch pipe Q3 turns off; Along with the rising of Drain terminal voltage, because high_voltage isolation pipe Q5 is in conducting state, the source voltage of high_voltage isolation pipe Q5 and the grid voltage of charging control valve Q4 rise thereupon, when the grid voltage of the control valve Q4 that charges is greater than the threshold value of charging control valve Q4, charging control valve Q4 conducting, at this moment Drain end charges to the first electric capacity C1 by high_voltage isolation pipe Q5 and charging control valve Q4, and VCC terminal voltage rises.As V3<VCC terminal voltage <V2, the signal ON opening comparator U2 output is high level, first threshold selects control switch K1 conducting, Second Threshold selects control switch K2 to disconnect, and the first feedback voltage V 1 is imported into the normal phase input end opening comparator U2.As VCC terminal voltage >V1, the output signal ON opening comparator U2 is low level, the output signal OFF now turning off comparator U3 is also low level, the signal EN that second NOR gate U6 exports is high level, and the output of d type flip flop U8 controls by pwm signal and the output signal ON opening comparator U2; Meanwhile, first threshold selects control switch K1 to disconnect, and Second Threshold selects control switch K2 conducting, and the second feedback voltage V 2 is imported into the normal phase input end opening comparator U2; If pwm signal does not have pulse to export, keep low level, then discharge control switch pipe Q3 is in off state always, the grid voltage of charging control valve Q4 is still greater than the unlatching threshold value of charging control valve Q4, first electric capacity C1 continues charging, until reach the pinch-off threshold of high_voltage isolation pipe Q5, high_voltage isolation pipe Q5 turns off, and charging terminates; When PWM is high level, the signal Charge that logic control element 511 exports is high level, discharge control switch pipe Q3 conducting, and the grid voltage of charging control valve Q4 is dragged down, and charging control valve Q4 turns off, and VCC holds to internal module electric discharge, and VCC terminal voltage declines; If before pwm signal trailing edge, VCC terminal voltage is still greater than the second feedback voltage V 2, the output signal ON then opening comparator U2 is still low level, the output signal ON_hys of the first inverter U4 is high level, the signal of the R end input of d type flip flop U8 is still high level, and when pwm signal trailing edge comes interim, the output (Q end) of d type flip flop U8 is high level, the output signal Charge of logic control element 511 is still high level, and VCC end is still in discharge condition; Until VCC terminal voltage <V2, open comparator U2 and output signal ON recovery high level, normal phase input end is V1, now VCC terminal voltage >V3, the output signal OFF therefore turning off comparator U3 is still low level, and the signal EN that the second NOR gate U6 exports maintains high level, if now period is opened on former limit, pwm signal is high level, and the output signal Change of logic control element 511 is still high level, and VCC end is still in discharge condition; Have no progeny in former frontier juncture, pwm signal trailing edge, d type flip flop U8 output low level, pwm signal is low level, the output signal Charge of logic control element 511 becomes low level, and discharge control switch pipe Q3 turns off, and the grid voltage of charging control valve Q4 is driven high, charging control valve Q4 conducting, VCC holds charging, before VCC terminal voltage arrives the first feedback voltage V 1, if open period on former limit, pwm signal is high level, and VCC end is still discharge condition; Loop control VCC like this holds the discharge and recharge to electric capacity C1, VCC terminal voltage is maintained between the first feedback voltage V 1 and the second feedback voltage V 2.Wherein, VCC terminal voltage, turn off comparator U3 output signal OFF, open the first output 1 ' that comparator U2 outputs signal ON, signal EN that the second NOR gate U6 exports, logical AND driver module 540 ' oscillogram of the signal PWM that exports and time limit ON time Tons as shown in Figure 6.
Refer to Fig. 7, in the former limit feedback LED drive circuit that the utility model provides, described time limit ON time detecting module 550 comprises current source U10, first switching tube Q6, second switch pipe Q7, 3rd switching tube Q8, 4th switching tube Q9, 5th switching tube Q10, 6th switching tube Q11, 7th switching tube Q12, 8th switching tube Q13, Schmidt trigger U11, second inverter U13, 3rd inverter U18, 4th inverter U19, four nor gate U14, 5th NOR gate U15, two inputs or door U16 and three input NOR gate U17, also comprise high level conducting, low level turns off, the first K switch 3 controlled by the output end signal A of three input NOR gate U17 and high level conducting, low level turns off, by two input or door U16 output end signal B control second switch K4, the source electrode of described first switching tube Q6 connects the output (namely the VCC of converter chip hold) started with supply module 510, and the drain electrode of described first switching tube Q6 is one end of the input of secondary limit ON time detecting module 550, the grid of connection power switch pipe Q1, the drain electrode of second switch pipe Q7, the grid of the 3rd switching tube Q8, the grid of the 4th switching tube Q9 and the first K switch 3, the grid of described second switch pipe Q7 connects the first output of logical AND driver module, the source electrode of described second switch pipe Q7 connects the drain electrode of the 3rd switching tube Q8, the source electrode of described 3rd switching tube Q8 connects the source electrode of the 4th switching tube Q9 and the negative pole of current source U10, the drain electrode of described 4th switching tube Q9 connects the source electrode of the 5th switching tube Q10, and the grid of described 5th switching tube Q10 connects the first output of logical AND driver module, the positive pole of described current source U10 connects the grid of the drain electrode of the 6th switching tube Q11, the grid of the 6th switching tube Q11, the grid of the 7th switching tube Q12 and the 8th switching tube Q13, the source ground of described 6th switching tube Q11, the drain electrode of described 7th switching tube Q12 connect the drain electrode of the 5th switching tube Q10, Schmidt trigger U11 input, also by second switch K4 ground connection, the source ground of described 7th switching tube Q12, the drain electrode of described 8th switching tube Q13 connects the other end of the first K switch 3, the source ground of described 8th switching tube Q13, the output of described Schmidt trigger U11 connects the input of the second inverter U13, the output of described second inverter U13 connects the first input end of four nor gate U14, the output of described four nor gate U14 connects the first input end of the 5th NOR gate U15, second input of described 5th NOR gate U15 connects the first output of logical AND driver module and the first input end of two inputs or door U16, the output of described 5th NOR gate U15 connects second input of four nor gate U14, second input of two inputs or door U16 and the first input end of three input NOR gate U17, the output of described two inputs or door U16 connects the input of the 3rd inverter U18, the output of described 3rd inverter U18 connects the grid of the first switching tube Q6, second input of described three input NOR gate U17 connects the first output of logical AND driver module, 3rd input of described three input NOR gate U17 connects the output of the 4th inverter U19, and the output of described three input NOR gate U17 is time output of limit ON time detecting module, connects the input of constant-current control module, the input of described 4th inverter sU19 is Enable Pin, normal work time be high level.Wherein, described first switching tube Q6, second switch pipe Q7, the 3rd switching tube Q8, the 4th switching tube Q9 and the 5th switching tube Q10 are P channel MOS tube; Described 6th switching tube Q11, the 7th switching tube Q12 and the 8th switching tube Q13 are N-channel MOS pipe.
Seeing also Fig. 7 and Fig. 2, when former limit is opened, the first output 1 ' of logical AND driver module 540 ' the signal PWM that exports is high level, source drive pipe Q2 conducting, second switch pipe Q7 disconnects, the output signal A of three input NOR gate U17 is low level, first K switch 3 disconnects, the output signal B of two inputs or door U16 is high level, 3rd inverter U18 output low level, the first switching tube Q6 conducting, is pulled to high level by the grid of power switch pipe Q1, power switch pipe Q1 conducting, the drain terminal voltage of power switch pipe Q1 is pulled to low level, the output end signal B of two inputs or door U16 is high level, second switch K4 conducting, and the 5th switching tube Q10 disconnects, and the drain electrode of the 5th switching tube Q10 is pulled to low level, and namely the input of Schmidt trigger U11 is low level, pwm signal is high level, the 5th NOR gate U15 output low level, former limit is opened, former limit inductive current rises, voltage on primary current sampling resistor (the first resistance R1) rises thereupon, until reach the threshold voltage Vocp of Cycle by Cycle current comparator OCP, first output 1 ' of control logic and driver module 540 ' output low level signal, namely pwm signal is low level, source drive pipe Q2 disconnects, the drain terminal voltage of power switch pipe Q1 is elevated to and is greater than input line voltage, make time polygonal voltage higher than the cathode voltage Vout of LED group 40, first diode D1 conducting, secondary limit starts electric discharge, at whole limit interdischarge interval, the drain terminal voltage of power switch pipe Q1 maintains and is greater than input line voltage, now, the output of the 5th NOR gate U15 still maintains low level, and the output end signal B of two inputs or door U16 is low level, and second switch K4 disconnects, and the first switching tube Q6 disconnects, input due to the 4th inverter U19 is Enable Pin, normal work time be high level, therefore the 4th inverter U19 output low level, three input NOR gate U17 output end signal A are high level, and also namely break in former frontier juncture.Pwm signal low level is for opening starting point in time limit, now, 5th switching tube Q10 and the equal conducting of second switch pipe Q7, first K switch 3 conducting, the grid voltage of power switch pipe Q1 equals the grid source pressure drop Vgsp that VCC terminal voltage deducts the 3rd switching tube Q8, by the ratio of appropriate design the 7th switching tube Q12 and the 8th switching tube Q13 and the ratio of the 3rd switching tube Q8 and the 4th switching tube Q9, the input voltage of now Schmidt trigger U11 is made still to maintain low level, after the demagnetization of secondary limit terminates, the drain terminal voltage of power switch pipe Q1 falls after rise rapidly, represent because power switch pipe Q1 has dotted line in gate-drain parasitic capacitances Cgd(Fig. 7), and according to circuit theory, electric capacity both end voltage difference can not be suddenlyd change, the sharply decline of drain terminal voltage (gate-drain parasitic capacitances Cgd top crown voltage), the grid end of power switch pipe Q1 (gate-drain parasitic capacitances Cgd bottom crown) voltage is also decreased, the electric current of the 3rd switching tube Q8 is increased rapidly, the electric current of the 4th switching tube Q9 increases thereupon, and be greater than the electric current of the 7th switching tube Q12, the input voltage of Schmidt trigger U11 is pulled to high level, four nor gate U14 output low level, 5th NOR gate U15 exports high level, the output signal A of three input NOR gate U17 becomes low level.Therefore the signal A exported at secondary limit discharge regime secondary limit ON time detecting module 550 is high level, low level is in all the other times, namely the time of signal A output high level is time limit Tons discharge time, thus has detected secondary limit Tons discharge time exactly.
Refer to Fig. 2, in the former limit feedback LED drive circuit that the utility model provides, described snubber module 20 comprises the 5th resistance R5, the 4th electric capacity C4 and the 3rd diode D3, described alternating current input J1 connects one end of one end of the 5th resistance R5, one end of the 4th electric capacity C4 and transformer 30 former limit winding Np by rectifying and voltage-stabilizing module 10, described 5th resistance R5 and the other end of the 4th electric capacity C4 are all connected the negative pole of the 3rd diode D3, and the positive pole of described 3rd diode D3 connects the other end of former limit winding Np and the Drain end of converter chip U1.
In sum, described converter chip U1 adopts 700V superhigh pressure technique, by power switch pipe Q1 Single-Chip Integration, while improving integrated level, reduces the requirement to encapsulation cavity volume; By by built-in for former limit sampling resistor, eliminate CS pin; Indirectly detect the erasing time by the parasitic gate leakage capacitance of built-in power switching tube Q1, eliminate FB pin; By the combination of above technology, make chip only need three pins, TO-92 can be adopted to encapsulate, and packaging cost is low.Built-in startup and supply module, high voltage startup and power supply can be realized, compared with legacy system, eliminate starting resistance, auxiliary winding, auxiliary limit rectifier diode, auxiliary limit divider resistance and primary current sampling resistor, simplify transformer manufacturing technological process, decrease peripheral component quantity, reduce further cost.
Be understandable that; for those of ordinary skills; can be equal to according to the technical solution of the utility model and utility model design thereof and replace or change, and all these change or replace the protection range that all should belong to the claim appended by the utility model.
Claims (10)
1. a former limit feedback LED drive circuit, is characterized in that, comprise alternating current input, the first electric capacity, the second electric capacity, the first diode;
There is the transformer of former limit winding and secondary winding;
Alternating current for inputting alternating current input carries out rectification and voltage stabilizing, and exports to the rectifying and voltage-stabilizing module of snubber module;
For absorbing the snubber module of the self-induced e.m.f of described former limit winding;
Be DC voltage by AC voltage transitions, and export the converter chip of constant current;
Described alternating current input is by rectifying and voltage-stabilizing model calling snubber module, one end of the former limit winding of described snubber model calling transformer, the other end of described former limit winding connects the Drain end of converter chip, the VCC end of described converter chip is by the first capacity earth, the GND of described converter chip holds ground connection, one end of described secondary winding connects the positive pole of the first diode, the negative pole of described first diode by the second capacity earth, also by LED group ground connection, the other end ground connection of described secondary winding;
Described converter chip produces power supply, inner integrated primary current sampling resistor by Drain end, by the gate leakage capacitance sampling time limit ON time of built-in power switching tube, and described power switch pipe Single-Chip Integration.
2. former limit according to claim 1 feedback LED drive circuit, it is characterized in that, described converter chip comprises power switch pipe, source drive pipe, the first resistance, the second diode;
For generation of startup and the supply module of built-in power supply;
The biasing module started with supply module is fed back to for generation of reference voltage;
For detecting former limit peak current, keep the Cycle by Cycle current comparator module that the peak current of each cycle is constant;
Utilize the gate-drain parasitic capacitances of power switch pipe, indirectly the secondary limit ON time detecting module of sampling time limit ON time;
For coming control logic and driver module according to time limit ON time, thus control the constant-current control module of output current;
For carrying out logical operation, output drive signal controls the logical AND driver module of the turn-on and turn-off of power switch pipe and source drive pipe;
The input of described startup and supply module is that the Drain of converter chip holds, connect the drain electrode of power switch pipe, described startup is connected converter chip VCC with the output of supply module holds, also connect the input of biasing module, the output of described biasing module connects the first input end of Cycle by Cycle current comparator module, the output of described Cycle by Cycle current comparator module connects the first input end of logical AND driver module, first output of described logical AND driver module connects the grid of source drive pipe, the source electrode of described source drive pipe connects the second input of Cycle by Cycle current comparator module, also by the first grounding through resistance, the grid of described power switch pipe connects the second output of logical AND driver module, the input of secondary limit ON time detecting module, the output of described limit ON time detecting module connects the input of constant-current control module, the output of described constant-current control module connects the second input of logical AND driver module, the source electrode of described power switch pipe connects the drain electrode of source drive pipe and the positive pole of the second diode, and the negative pole of described second diode connects the output started with supply module.
3. former limit according to claim 2 feedback LED drive circuit, it is characterized in that, first feedback signal output of described biasing module connects the first feedback signal input terminal started with supply module, second feedback signal output of biasing module connects the second feedback signal input terminal started with supply module, and the 3rd feedback signal output of biasing module connects the 3rd feedback signal input terminal started with supply module, described startup and supply module comprise unlatching comparator, turn off comparator, first threshold selects control switch, Second Threshold selects control switch, logic control element, second resistance, 3rd resistance, 4th resistance, discharge control switch pipe, high_voltage isolation pipe and charging control valve, described first threshold selects one end of control switch to be start the first feedback signal input terminal with supply module, connect the first feedback signal output of biasing module, described first threshold selects the other end of control switch to connect the normal phase input end opening comparator, described Second Threshold selects one end of control switch to be start the second feedback signal input terminal with supply module, connect the second feedback signal output of biasing module, described Second Threshold selects the other end of control switch to connect the normal phase input end opening comparator, the output of described unlatching comparator connects the first input end of logic control element, the normal phase input end of described shutoff comparator is start the 3rd feedback signal input terminal with supply module, connect the 3rd feedback signal output of biasing module, the output of described shutoff comparator connects the second input of logic control element, the output of described logic control element connects the grid of discharge control switch pipe, the source ground of described discharge control switch pipe, the drain electrode of described discharge control switch pipe connects the grid of charging control valve, also connect the source electrode of high_voltage isolation pipe and the drain electrode of charging control valve by the second resistance, the grounded-grid of described high_voltage isolation pipe, the drain electrode of described high_voltage isolation pipe is start the input with supply module, the source electrode of described charging control valve is start the output with supply module, connect one end of the 3rd resistance, the other end of described 3rd resistance connects the inverting input opening comparator and the inverting input turning off comparator, also by the 4th grounding through resistance.
4. former limit according to claim 3 feedback LED drive circuit, it is characterized in that, first feedback signal output of described biasing module exports the first feedback voltage, second feedback signal output of described biasing module exports the second feedback voltage, 3rd feedback signal output of described biasing module exports the 3rd feedback voltage, described first feedback voltage is greater than the second feedback voltage, and described second feedback voltage is greater than the 3rd feedback voltage.
5. former limit according to claim 4 feedback LED drive circuit, is characterized in that, described logic control element comprises the first inverter, d type flip flop, the first NOR gate, the second NOR gate, the 3rd NOR gate and first or door, the input of described first inverter and the first input end of the first NOR gate are the first input end of logic control element, connect the output opening comparator, second input of described first NOR gate and the second input of the second NOR gate are the second input of logic control element, connect the output turning off comparator, the output of described first NOR gate connects the first input end of the 3rd NOR gate, the output of described 3rd NOR gate connects the first input end of the second NOR gate, the output of described second NOR gate connects the second input of the 3rd NOR gate and the R end of d type flip flop, the C end of described d type flip flop connects the first output of logical AND driver module, the D of described d type flip flop holds the output of connection first inverter, the Q of described d type flip flop holds the first input end of connection first or door, described first or the second input of door connect the first output of logical AND driver module, first or the output of door be the output of logic control element, connect the grid of discharge control switch pipe.
6. former limit according to claim 5 feedback LED drive circuit, it is characterized in that, described time limit ON time detecting module comprises current source, first switching tube, second switch pipe, 3rd switching tube, 4th switching tube, 5th switching tube, 6th switching tube, 7th switching tube, 8th switching tube, Schmidt trigger, second inverter, 3rd inverter, 4th inverter, four nor gate, 5th NOR gate, two inputs or door and three input NOR gate, also comprise high level conducting, low level turns off, the first switch controlled by the output end signal of three input NOR gate and high level conducting, low level turns off, by two input or door output end signal control second switch, the source electrode of described first switching tube connects the output started with supply module, and the drain electrode of described first switching tube is time input of limit ON time detecting module, the grid connecting power switch pipe, the drain electrode of second switch pipe, the grid of the 3rd switching tube, the grid of the 4th switching tube and one end of the first switch, the grid of described second switch pipe connects the first output of logical AND driver module, the source electrode of described second switch pipe connects the drain electrode of the 3rd switching tube, the source electrode of described 3rd switching tube connects the source electrode of the 4th switching tube and the negative pole of current source, the drain electrode of described 4th switching tube connects the source electrode of the 5th switching tube, and the grid of described 5th switching tube connects the first output of logical AND driver module, the positive pole of described current source connects the grid of the drain electrode of the 6th switching tube, the grid of the 6th switching tube, the grid of the 7th switching tube and the 8th switching tube, the source ground of described 6th switching tube, the drain electrode of described 7th switching tube connect the drain electrode of the 5th switching tube, Schmidt trigger input, also by second switch ground connection, the source ground of described 7th switching tube, the drain electrode of described 8th switching tube connects the other end of the first switch, the source ground of described 8th switching tube, the output of described Schmidt trigger connects the input of the second inverter, the output of described second inverter connects the first input end of four nor gate, the output of described four nor gate connects the first input end of the 5th NOR gate, second input of described 5th NOR gate connects the first output of logical AND driver module and the first input end of two inputs or door, the output of described 5th NOR gate connects the second input of four nor gate, second input of two inputs or door and the first input end of three input NOR gate, the output of described two inputs or door connects the input of the 3rd inverter, the output of described 3rd inverter connects the grid of the first switching tube, second input of described three input NOR gate connects the first output of logical AND driver module, 3rd input of described three input NOR gate connects the output of the 4th inverter, and the output of described three input NOR gate is time output of limit ON time detecting module, connects the input of constant-current control module, the input of described 4th inverter is Enable Pin, normal work time be high level.
7. former limit according to claim 6 feedback LED drive circuit, it is characterized in that, described first switching tube, second switch pipe, the 3rd switching tube, the 4th switching tube and the 5th switching tube are P channel MOS tube; Described 6th switching tube, the 7th switching tube and the 8th switching tube are N-channel MOS pipe.
8. former limit according to claim 6 feedback LED drive circuit, is characterized in that, the 3rd electric capacity that described rectifying and voltage-stabilizing module comprises rectifier bridge and is connected in parallel with rectifier bridge.
9. former limit according to claim 8 feedback LED drive circuit, it is characterized in that, described snubber module comprises the 5th resistance, the 4th electric capacity and the 3rd diode, described alternating current input is by one end of rectifying and voltage-stabilizing model calling the 5th resistance, one end of the 4th electric capacity and one end of transformer primary side winding, described 5th resistance and the other end of the 4th electric capacity are all connected the negative pole of the 3rd diode, and the positive pole of described 3rd diode connects the other end of former limit winding and the Drain end of converter chip.
10. former limit according to claim 9 feedback LED drive circuit, it is characterized in that, described power switch pipe is 700V extra high tension power switching tube.
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| CN201520163735.6U CN204482091U (en) | 2015-03-23 | 2015-03-23 | A kind of former limit feedback LED drive circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107733241A (en) * | 2017-11-14 | 2018-02-23 | 深圳睿舍智能科技有限公司 | Double primary side insulating power supplies |
| CN107733255A (en) * | 2017-10-20 | 2018-02-23 | 福建省福芯电子科技有限公司 | A kind of double winding power circuit |
| CN113037070A (en) * | 2019-12-25 | 2021-06-25 | 上海芯熠微电子有限公司 | Fast starting circuit of switching power supply |
-
2015
- 2015-03-23 CN CN201520163735.6U patent/CN204482091U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107733255A (en) * | 2017-10-20 | 2018-02-23 | 福建省福芯电子科技有限公司 | A kind of double winding power circuit |
| CN107733241A (en) * | 2017-11-14 | 2018-02-23 | 深圳睿舍智能科技有限公司 | Double primary side insulating power supplies |
| CN113037070A (en) * | 2019-12-25 | 2021-06-25 | 上海芯熠微电子有限公司 | Fast starting circuit of switching power supply |
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