CN106954307B - A kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power - Google Patents

A kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power Download PDF

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CN106954307B
CN106954307B CN201710227358.1A CN201710227358A CN106954307B CN 106954307 B CN106954307 B CN 106954307B CN 201710227358 A CN201710227358 A CN 201710227358A CN 106954307 B CN106954307 B CN 106954307B
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CN106954307A (en
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邓小兵
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SHENZHEN TPOWER SEMICONDUCTOR Co Ltd
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SHENZHEN TPOWER SEMICONDUCTOR Co Ltd
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10Controlling the intensity of the light
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The invention discloses a kind of PWM adjusting control circuits for High Power Factor primary side feedback LED drive power, including:One voltage reference generates unit;One PWM processing units;One current sampling unit;One error amplifying unit;One constant-current control unit;One zero passage detection unit;One transformer secondary output winding free time control unit, for being controlled when PWM is dimmed transformer secondary output winding free time size, the signal of output control power switch pipe conducting;One logical AND driving unit, for carrying out logic control, and then driving power switching tube and control transformer secondary output winding free time control unit to the output signal of constant-current control unit and transformer secondary output winding free time control unit.

Description

A kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power
Technical field
The present invention relates to a kind of PWM light adjusting circuits more particularly to a kind of High Power Factor primary side feedback LED that is used for drive electricity The PWM light adjusting circuits in source.
Background technology
With the development of LED drive power and the requirement of energy-saving and environment friendly, LED drive power is generally with tune at present Light function.In various dimming modes, PWM light modulations are using one kind the most universal and abundant.The PWM tune of LED drive power Optical circuit controls the output current of LED drive power using the pwm signal of external MCU outputs, so as to adjust the brightness of LED, To realize the purpose of PWM light modulations.
For the primary side feedback LED drive power of High Power Factor, in the output electricity of pwm signal control LED drive power In terms of stream, traditional solution is that the external MCU pwm signals exported are converted into corresponding analog voltage, is believed according to PWM Number duty ratio difference be converted into the analog voltage of different voltages size.Benchmark electricity of the analog voltage as LED output currents Pressure, so as to obtain different size of LED output currents.
Fig. 1 is traditional High Power Factor primary side feedback LED drive power with PWM dimming functions, is generally included:It is whole Bridge D1~D4, input filter capacitor C1 are flowed, starts resistance R1, power supply capacitor C2, control chip U1, FB divider resistance R1, R2 is whole Flow diode D5, primary winding peak point current sampling resistor R4, power switch pipe Q1, transformer T1, secondary commutation two Pole pipe D6, output capacitance C3, output resistance R5 and LED load LEDs.Inside control chip U1, generally include:PWM light modulation controls Unit processed, current sampling unit, error amplifying unit, voltage reference cell, constant-current control unit and logical AND driving unit;Its The circuit of middle PWM dimming control units is as shown in Figure 2.When pwm signal is high level, switch S1 is closed, switch S2 is disconnected, this When LED output currents reference voltage REF charge to filter capacitor C1;When pwm signal is low level, switch S1 breaks It opens, switch S2 closures, filter capacitor C1 starts to discharge over the ground at this time;Therefore switched by the low and high level of pwm signal, most The reference voltage REF filtering of LED output currents becomes the analog voltage of a REFD at last, LED outputs electricity when being dimmed as PWM The reference voltage of stream.With the change in duty cycle of pwm signal, then the reference voltage REFD of LED output currents also phases when PWM is dimmed It should change, so as to obtain different size of LED output currents, to realize the purpose of PWM light modulations.
Fig. 3 is accounted for for traditional High Power Factor primary side feedback LED drive power with PWM dimming functions in different PWM Sky than when corresponding key node oscillogram.From the figure, it can be seen that when PWM duty cycle is 50%, since LED is exported at this time Current reference voltage for it is uncomfortable smooth when half, then corresponding primary winding peak current level and control chip work Make the period also for it is uncomfortable smooth when half.Further, when PWM duty cycle is 25%, due to LED output currents base at this time Quasi- voltage for it is uncomfortable smooth when 1/4, then corresponding primary winding peak current level and control chip work period 1/4 when being also uncomfortable smooth.It is hereby achieved that in the PWM light modulations of High Power Factor primary side feedback LED drive power, this Kind reduces merely the circuit of LED output current reference voltages by pwm signal, in the PWM light modulations purpose for realizing LED simultaneously Also the working frequency of LED drive power is persistently increased.
The PWM light adjusting circuits for being traditionally used for High Power Factor primary side feedback LED drive power have the following disadvantages:Tradition PWM light adjusting circuits in dimming process with the duty ratio of pwm signal reduction can increase LED drive power work frequency Rate.The increase of LED drive power working frequency can then increase the power consumption of power switch pipe and whole system, can also increase entire The Wen Sheng of LED drive power, so as to reduce the efficiency and reliability of system;More seriously, the increase of working frequency can make The electromagnetic interference for obtaining entire LED drive power becomes larger, this needs to increase additional anti-electromagnetic interference circuit, so as to increase system Cost and debugging difficulty.In addition, traditional PWM light adjusting circuits in dimming process with the duty ratio of pwm signal reduce meeting The corresponding peak point current for reducing primary winding.When peak point current reduces to a certain extent, due to controlling chip interior The effect of minimum turn-on time can cause peak point current no longer to reduce with the reduction of pwm signal duty ratio so that LED is exported Electric current does not change with the variation of PWM dim signal duty ratios.So as to cause PWM light modulations, in low duty ratio, there are poor tune Actinic degree, therefore limited to the range of PWM dimming duty cycles.
It is set in the High Power Factor primary side feedback LED drive power of PWM dimming behaviors be particular about cost and pursue high quality In meter, this traditional PWM adjusting control circuits increasingly have limitation.
Invention content
For the limitation of traditional PWM dimming control techniques, the invention discloses one kind to be used for High Power Factor primary side The PWM adjusting control circuits of LED drive power are fed back, which includes:One voltage reference generates unit, uses In output current reference voltage and other reference voltages needed for generation;One PWM processing units, for external input PWM to be believed Number it is converted into the current reference analog voltage signal of chip interior;One current sampling unit, for primary winding Peak point current is sampled;One error amplifying unit, for the voltage and PWM for sampling primary winding peak point current The benchmark simulation voltage being converted into carries out error amplification;One constant-current control unit, for carrying out constant current control to output LED current System, the signal that output control power switch pipe is closed;One zero passage detection unit, during for transformer secondary output winding current zero passage Quarter is detected;One transformer secondary output winding free time control unit, for empty to transformer secondary output winding when PWM is dimmed Size is controlled between idle, the signal of output control power switch pipe conducting;One logical AND driving unit, for constant current control The output signal of unit and transformer secondary output winding free time control unit processed carries out logic control, and then driving power switchs Pipe and control transformer secondary output winding free time control unit.
Further, the invention discloses a kind of High Power Factor primary side feedback LED constant current driving power, LED perseverances Stream driving power further includes:One rectifier bridge, an input filter capacitor, one starts resistance, a power supply capacitor, a FB voltage-splitter resistance nets Network, a rectifier diode, a primary winding peak point current sampling resistor, a power switch pipe, a transformer, a grade Output diode, an output capacitance, an output resistance and a LED load.
Further, first output terminal of the voltage reference cell connects first input of the PWM processing units End, second output terminal and third output terminal connect the first of the transformer secondary output winding free time control unit respectively A input terminal and second input terminal;Another input terminal of the PWM processing units connects externally input pwm signal, defeated Outlet connects first input terminal and the transformer secondary output winding free time control unit of the error amplifying unit respectively Third input terminal;The input terminal of the current sampling unit connects the output of the primary winding peak point current sampling resistor End, output terminal connect another input terminal of the error amplifying unit;The input terminal of the constant-current control unit connects the error The output terminal of amplifying unit, output terminal connect first input terminal of the logical AND driving unit;The zero passage detection unit Input terminal connects the output terminal of the FB resistor voltage divider networks, and it is single that output terminal connects the control of transformer secondary output winding free time 4th input terminal of member;The output terminal of the transformer secondary output winding free time control unit connects the logical AND driving unit Another input terminal;The output terminal of the logical AND driving unit connects the input terminal and the transformer of the power switch pipe respectively 5th input terminal of secondary windings free time control unit.
Further, which includes:One switch control logic unit, one Operational amplifier unit, a resistance, a NMOS transistor, a current mirror, first switch, second switch, a delay capacitor, first Comparator unit and the second comparator unit.One positive input terminal of the first comparator unit connects the voltage reference cell Second output terminal, negative input end connect the output terminal of the PWM processing units, and output terminal connects the switch control logic unit First input terminal;Second input terminal of the unit of the switch control logic connects the output terminal of the zero passage detection unit, Its another input terminal connects the output terminal of the logical AND driving unit, and output terminal controls first switch and second to open respectively It closes;One positive input terminal of the operational amplifier unit and the negative input end of first comparator connect, negative input end and the NMOS The source electrode connection of transistor, output terminal are connect with the grid of the NMOS transistor;The resistance one end is grounded, and the other end is with being somebody's turn to do The source electrode connection of NMOS transistor;The current mirror one end is connect with the drain electrode of the NMOS transistor, the other end and the first switch One end connection;The other end of the first switch connects the negative input end of second comparator unit;One end of the second switch Ground connection, the other end connect the negative input end of second comparator unit;One end ground connection of the delay capacitor, the other end is with being somebody's turn to do The negative input end connection of second comparator unit;The positive input terminal of second comparator unit connects the of the voltage reference cell Three output terminals, output terminal connect another input terminal of the logical AND driving unit.
With being traditionally used for compared with the PWM dimming control techniques of High Power Factor primary side feedback LED drive power, this hair The bright PWM adjusting control circuits for High Power Factor primary side feedback LED drive power, by reduction output current benchmark The free time of transformer secondary output winding is increased while voltage, this can control the working frequency of LED drive power one In a suitable range, the working frequency of LED drive power is avoided as PWM dimming duty cycles reduce and continue increased ask Topic;Simultaneously as increasing the free time of transformer secondary output winding, then the peak point current of primary winding is believed in PWM It is still controlled in a rational range during number duty ratio very little, which improve LED output currents when PWM is low duty ratio The light modulation linearity.Therefore, pass through the PWM adjusting control circuits of the present invention, the LED drive power of High Power Factor primary side feedback It can realize superior PWM dimming effects.
Description of the drawings
It can be obtained further by following detailed description of the invention and institute's accompanying drawings about the advantages and spirit of the present invention Solution.
Fig. 1 is traditional High Power Factor primary side feedback constant current driver circuit for LED with PWM dimming functions;
Fig. 2 is the PWM adjusting control circuits for being traditionally used for High Power Factor primary side feedback constant current driver circuit for LED;
Fig. 3 is the key node oscillogram of traditional constant current driver circuit for LED with PWM dimming functions;
Fig. 4 is the High Power Factor primary side feedback constant current driver circuit for LED with PWM dimming functions of the present invention;
Fig. 5 is a specific implementation figure of the transformer secondary output winding free time control unit of the present invention;
Fig. 6 is the key node oscillogram of the constant current driver circuit for LED with PWM dimming functions of the present invention.
Specific embodiment
Specific embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings.
The present invention solves the PWM dimming control techniques for being traditionally used for High Power Factor primary side feedback LED drive power The working frequency of LED drive power reduce the problem of persistently increase with PWM dimming duty cycles, while also solve tradition PWM dimming control techniques pwm signal be low duty ratio when output current dim linearity effect it is undesirable the problem of, provide The PWM adjusting control circuits that solve the above problems.Transformer is increased while by reduction output current reference voltage The method of the free time of secondary windings controls the working frequency of LED drive power in a suitable range, while handle The peak point current of primary winding is still controlled in pwm signal duty ratio very little in a rational range, is solved The problem of working frequency of LED drive power persistently increases as PWM dimming duty cycles reduce;And it is defeated to improve LED Go out the light modulation linearity of the electric current when PWM is low duty ratio, realize superior PWM dimming effects.
The output current of the LED drive power of High Power Factor primary side feedback can be represented by the following formula:
Wherein, output current reference voltage when VREFD is dimmed for PWM;RCS is sampled for primary winding peak point current Resistance value;NP is primary umber of turn;NS is transformer secondary output umber of turn.It can be seen that, PWM is being carried out from above formula During light modulation, traditional solution is simple reduction output current reference voltage V REFD, defeated so as to be proportionally reduced LED Go out electric current, to realize the purpose of light modulation.For High Power Factor primary side feedback LED drive power, output current base when PWM is dimmed Quasi- voltage VREFD reduces, and the armature winding peak point current and secondary windings peak point current that can cause transformer reduce, so as to power The turn-on time of switching tube is corresponding to the erasing time of transformer secondary output winding to be reduced.Therefore, the working frequency of LED drive power It can continue to increase with the reduction of PWM dimming duty cycles.As seen from Figure 3, gradually subtracting with the duty ratio of pwm signal Small, primary winding peak point current is gradually decrease to the value of a very little, and the frequency of power switch pipe is gradually increased to one A very high value.
The output current of the LED drive power of High Power Factor primary side feedback and primary winding peak point current, change There are following relationships for the free time of depressor secondary windings and the working frequency of power switch pipe:
Wherein, IPPKFor primary winding peak point current;TDISFor the transformer secondary output winding erasing time;TONFor work( Rate switching tube turn-on time;TFREEFor transformer secondary output winding free time.From above formula it can be seen that, when PWM is dimmed, LED Output current can reduce as PWM duty cycle reduces, at this time by transformer secondary output winding free time TFREEIt increases Method can cause the working frequency fosc of power switch pipe not reduce with PWM duty cycle and persistently increase;While but also Primary winding peak point current IPPKIt is still controlled in PWM duty cycle very little in a rational range.Therefore, this hair The circuit of the bright free time that transformer secondary output winding is increased while disclose output current reference voltage reduction a kind of, It is undesirable to solve the problems, such as that working frequency during PWM light modulations continues to increase and dim the linearity, realizes superior PWM light modulations effect Fruit.
As shown in figure 4, the PWM brightness adjustment controls electricity for High Power Factor primary side feedback LED drive power for the present invention Road.Control circuit for LED drive power PWM light modulations includes:Voltage reference generates unit 415, PWM processing units 416, electricity Flow sampling unit 417;Error amplifying unit 418, constant-current control unit 419, zero passage detection unit 420, transformer secondary output winding Free time control unit 421, logical AND driving unit 422.
In PWM dimming process, the voltage reference is generated the output current of unit 415 by the PWM processing units 416 Reference voltage REF carries out switch filtering, and the output current reference voltage V REFD exported when PWM is dimmed amplifies to the error First input terminal of unit 418;With the reduction of pwm signal duty ratio, the output current reference voltage when PWM is dimmed VREFD also follows reduction;The error amplifying unit 418 is amplified during the work time by loop feedback and error so that institute The output current reference voltage V REFD stated when the output voltage SENSE of current sampling unit 417 is dimmed with the PWM is equal, then The crest voltage of the transformer peak point current sampling resistor 408 also accordingly reduces, so as to the armature winding of the transformer 409 Peak point current also accordingly reduces.When the duty ratio of the pwm signal is reduced to the output electricity so that the PWM processing units 416 When stream reference voltage V REFD is reduced to VREF1, the transformer secondary output winding free time control unit 421 is started to work, control Make the secondary windings free time of the transformer 409.The secondary windings free time of the transformer 409 is with the PWM The reduction of output current reference voltage V REFD during light modulation and increase so that the working frequency of the power switch pipe 407 Will not the lasting increase with the reduction of pwm signal duty ratio, be operated in a rational range.Simultaneously as the transformation The increase of the secondary windings free time of device 409, the error amplifying unit 418 under loop feedback and error amplification, So that the peak primary currents of the transformer 409 are still controlled in PWM duty cycle very little in a rational range.
Fig. 5 is a specific implementation figure of the transformer secondary output winding free time control unit 421 of the present invention.The change Depressor secondary windings free time control unit 421 is by operational amplifier unit 500, resistance 501, NMOS transistor 502, electric current Mirror 503, first comparator unit 504, switch control logic unit 505, first switch 506, second switch 507, delay capacitor 508 and second comparator unit 509 form.When the duty ratio of the pwm signal is reduced to so that the PWM processing units 416 Output current reference voltage V REFD when being reduced to VREF1, the first comparator unit 504 exported described in high level EN arrives First input terminal of switch control logic unit 505, then the switch control logic unit 505 start to work, described in control The disconnection of first switch 506 and the second switch 507 and closure.The operational amplifier unit 500 is single to PWM processing The output current reference voltage V REFD of member 416 carries out error amplification, when the output current reference voltage V REFD is smaller, then The electric current flowed through on the resistance 501 is smaller.The electric current flowed through on the resistance 501 carries out mirror image by the current mirror 503, The zero passage detection unit 420 exports ZCD high level in the 409 secondary winding current zero passage of transformer, described at this time to open Closing 505 output switch control signal of control logic unit causes the first switch 506 to be closed, and the second switch 507 disconnects, Then the output current of the current mirror 503 charges to the delay capacitor 508, the voltage on the delay capacitor 508 When RAMP rises to the positive input terminal voltage REF2 of second comparator, the second comparator output control signal ON to institute Logical AND driving unit 422 is stated, the output of logical AND driving unit 422 at this time controls what the power switch pipe 407 was connected Signal GD, at this time 505 output switch control signal of switch control logic unit disconnect the first switch 506, it is described Second switch 507 is closed, and the voltage RAMP on the delay capacitor 508 drops to ground at this time.With the output current benchmark Voltage VREFD is smaller, then the electric current flowed through on the resistance 501 is also smaller, then the RAMP voltages of the delay capacitor 508 rise Time to the positive input terminal voltage REF2 of second comparator is longer, idle so as to the secondary windings of the transformer 409 Time is also longer.It is achieved thereby that the secondary windings free time of the transformer 409 is controlled by pwm signal duty ratio Purpose.
Fig. 6 is the key node oscillogram of the constant current driver circuit for LED with PWM dimming functions of the present invention.From figure It can be seen that the free time of transformer secondary output winding is increased while by reduction output current reference voltage, The working frequency of LED drive power is controlled in a suitable range, meanwhile, the peak point current of primary winding is also controlled System is in a suitable range.Therefore, PWM adjusting control circuits of the invention solve the working frequency of LED drive power The problem of persistently increasing as PWM dimming duty cycles reduce;And LED output currents are improved when PWM is low duty ratio The light modulation linearity, realize superior PWM dimming effects, improve the q&r of LED drive power.
Described in this specification is only the preferable specific embodiment of the present invention, for illustrating the technical side of the present invention Case rather than limitation of the present invention, the design of all those skilled in the art according to the present invention by logic analysis, reasoning or Limited experiment come the present invention is made that some adjustment and change obtained from technical solution, such as by the present invention PWM tune The technology of light control circuit is applied to the non-isolated Boost topology of High Power Factor, non-isolated buck topology and non-isolated buck and opens up In the LED drive power flutterred.It is still the main idea place of the present invention, it all should be within the scope of the present invention.

Claims (5)

  1. A kind of 1. PWM light adjusting circuits for High Power Factor primary side feedback LED drive power, which is characterized in that the PWM tune Optical circuit includes:One voltage reference generates unit, for generating required output current reference voltage and other reference voltages;One PWM processing units, for external input pwm signal to be converted into the current reference analog voltage signal of chip interior;One electric current Sampling unit samples for the peak point current to primary winding;One error amplifying unit, for will be at the beginning of transformer The benchmark simulation voltage that the voltage and PWM that grade winding peak point current samples are converted into carries out error amplification;One current constant control list Member, for carrying out current constant control, the signal that output control power switch pipe is closed to output LED current;One zero passage detection unit, For being detected to transformer secondary output winding current zero-acrross ing moment;One transformer secondary output winding free time control unit is used In being controlled when PWM is dimmed transformer secondary output winding free time size, output controls the letter of power switch pipe conducting Number;One logical AND driving unit, for the output to constant-current control unit and transformer secondary output winding free time control unit Signal carries out logic control, and then driving power switching tube and control transformer secondary output winding free time control unit.
  2. 2. a kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power as described in claim 1, It is characterized in that, the PWM light adjusting circuits further include:One rectifier bridge, input filter capacitor start resistance, power supply capacitor, FB partial pressures Resistor network, rectifier diode, primary winding peak point current sampling resistor, power switch pipe, transformer, secondary output Diode, output capacitance, output resistance and LED load.
  3. 3. a kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power as claimed in claim 2, It being characterized in that, the voltage reference generates first input terminal of first output terminal connection PWM processing units of unit, Its second output terminal and third output terminal connect the first of the transformer secondary output winding free time control unit respectively A input terminal and second input terminal;Another input terminal of the PWM processing units connects externally input pwm signal, Output terminal connects first input terminal of the error amplifying unit and transformer secondary output winding free time control respectively The third input terminal of unit;The input terminal of the current sampling unit connects the primary winding peak point current sampling The output terminal of resistance, output terminal connect another input terminal of the error amplifying unit;The constant-current control unit it is defeated Enter the output terminal that end connects the error amplifying unit, output terminal connects first input of the logical AND driving unit End;The input terminal of the zero passage detection unit connects the output terminal of the FB resistor voltage divider networks, and output terminal connects the change 4th input terminal of depressor secondary windings free time control unit;The transformer secondary output winding free time control unit Output terminal connect another input terminal of the logical AND driving unit;The output terminal of the logical AND driving unit connects respectively Connect the input terminal of the power switch pipe and the 5th input terminal of the transformer secondary output winding free time control unit.
  4. 4. a kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power as described in claim 1, Be characterized in that, the transformer secondary output winding free time control unit by switch control logic unit, operational amplifier unit, Resistance, NMOS transistor, current mirror, first switch, second switch, delay capacitor, first comparator unit and the second comparator Unit forms, and a positive input terminal of the first comparator unit connects second output terminal of the voltage reference cell, Negative input end connects the output terminal of the PWM processing units, and output terminal connects first of the switch control logic unit Input terminal;Second input terminal of the unit of the switch control logic connects the output terminal of the zero passage detection unit, another One input terminal connects the output terminal of the logical AND driving unit, and output terminal controls first switch and second switch respectively; One positive input terminal of the operational amplifier unit and the negative input end of first comparator connect, negative input end and the NMOS The source electrode connection of transistor, output terminal are connect with the grid of the NMOS transistor;Resistance one end ground connection, the other end It is connect with the source electrode of the NMOS transistor;Described current mirror one end is connect with the drain electrode of the NMOS transistor, the other end with One end connection of the first switch;The other end of the first switch connects the negative input end of second comparator unit; One end ground connection of the second switch, the other end connect the negative input end of second comparator unit;The delay capacitor One end ground connection, the other end connect with the negative input end of second comparator unit;Second comparator unit is just Input terminal connects the third output terminal of the voltage reference cell, and output terminal connects the another of the logical AND driving unit A input terminal.
  5. 5. a kind of PWM for High Power Factor primary side feedback LED drive power as described in Claims 1 to 4 any one Light adjusting circuit, it is characterised in that:The PWM light adjusting circuits be applied to High Power Factor non-isolated boosting, it is non-isolated decompression and In the Topology Switch power-supply system of non-isolated buck.
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CN108366454A (en) * 2018-03-01 2018-08-03 深圳赫飞物联科技有限公司 A kind of compatible analog, digital dimming PWM primary sides regulate and control method
CN108366455B (en) * 2018-03-01 2019-09-03 深圳赫飞物联科技有限公司 It is a kind of that light-dimming method is simulated by the high P of primary side of pwm signal regulation

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CN206640841U (en) * 2017-04-10 2017-11-14 深圳天源中芯半导体有限公司 A kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power

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