CN103546143A - Feedback detection circuit - Google Patents
Feedback detection circuit Download PDFInfo
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- CN103546143A CN103546143A CN201210235233.0A CN201210235233A CN103546143A CN 103546143 A CN103546143 A CN 103546143A CN 201210235233 A CN201210235233 A CN 201210235233A CN 103546143 A CN103546143 A CN 103546143A
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Abstract
The invention provides a feedback detection circuit which is applicable to providing a feedback detection signal, so that a conversion circuit generates a driving power supply according to the feedback detection signal to drive a load. The feedback detection circuit comprises an operation conversion circuit and a signal limiting circuit, the operation conversion circuit generates the feedback detection signal according to an electrical level of a point to be detected coupled with the load and is provided with an operational amplifier, and the operational amplifier is coupled with the point to be detected to adjust the strength of the feedback detection signal by corresponding to the electrical level of the point to be detected. The signal limiting circuit is coupled with the operation conversion circuit to control the range of the feedback detection signal.
Description
Technical field
The invention relates to a kind of feedback sense circuit, espespecially a kind of feedback sense circuit with better transient response.
Background technology
In feedback control system, sometimes for example,, for the requirement in circuit design (: isolate), can use integrated circuit in feedback sense circuit.For instance, Fig. 1 be traditional optical coupling feedback circuit circuit diagram.Please refer to Fig. 1, the optical coupler PC in optical coupling feedback circuit can provide the good isolation effect between input and output.In order to control optical coupler PC, optical coupling feedback circuit has been used a shunt regulator TL431.One output voltage V out provides a reference edge of a voltage division signal input shunt regulator TL431 through a voltage divider VD.A cathode terminal of shunt regulator TL431 couples one end of a light-emitting diode of optical coupler PC, and an anode tap ground connection.The other end of the light-emitting diode in optical coupler PC couples output voltage V out by a resistance R, to receive luminous required electric power, and exports a feedback detection signal FB.Between the cathode terminal of shunt regulator TL431 and reference edge, can add a compensating circuit CN to stablize feedback loop.Yet, a few thing state constantly switch and to the higher system of the rate request of transient response in, the transient response speed of shunt regulator TL431 often becomes bottleneck, especially, when nonlinear load, its impact is especially obvious.
Fig. 2 is the circuit diagram of light-emitting diode pulse light modulation (Burst Dimming) system of traditional integrating power supply system architecture (LCD Integrated Power System, LIPS).Please refer to Fig. 2, the framework of the feedback sense circuit in the left side of Fig. 2 is identical with the framework of the feedback sense circuit shown in Fig. 1, only output voltage V out is replaced with a system voltage VCC.On the right side of Fig. 2, an anode of a light-emitting diode (LED) module LD couples a driving voltage VLED, and a negative terminal couples a transistor switch M.Transistor switch M receives an impulse width modulation and light adjusting signal DIM with conducting or shutoff accordingly.An anode of one diode D1 couples a dividing point of voltage divider VD, and a negative terminal couples the negative terminal of light-emitting diode (LED) module LD.When transistor switch M turn-offs, a level of the negative terminal of light-emitting diode (LED) module LD can raise.Now, diode D1 oppositely turn-offs, and a working point of shunt regulator TL431 determines (calling state one in the following text) by the voltage of the dividing point of voltage divider VD.When transistor switch M conducting, the level of the negative terminal of light-emitting diode (LED) module LD can reduce makes diode D1 conducting, and the working point of shunt regulator TL431 determines (calling state two in the following text) by the voltage of the negative terminal of light-emitting diode (LED) module LD.Therefore, feedback sense circuit can be switched back and forth between two above-mentioned operating states.For the moment, light-emitting diode (LED) module LD extinguishes state, and load is unloaded, provides a power-supply system (not shown) of driving voltage VLED to stop providing energy to light-emitting diode (LED) module LD.During state two, light-emitting diode (LED) module LD lights, and load is for fully loaded, and power-supply system needs the enough energy of supply immediately to make light-emitting diode (LED) module LD remain lightness stabilized.Yet, being subject to the restriction of shunt regulator TL431 transient response speed, power-supply system can not switch to fully loaded immediately from zero load, thereby causes while switching to state two by state one, and the energy supply of negative supply system is not enough, makes light-emitting diode (LED) module LD flicker.
Summary of the invention
Application restric-tion in the time of can causing state to switch in view of the transient response speed of feedback sense circuit of the prior art, the present invention utilizes a level of the feedback signal that a signal limitations circuit limitations feedback sense circuit produces, when state is switched, the adjusting range of one computing change-over circuit of feedback sense circuit is dwindled even not to be needed to adjust, and reaches therefrom the advantage that improves transient response speed.
For reaching above-mentioned purpose, the invention provides a kind of feedback sense circuit, be applicable to provide a feedback detection signal, make a change-over circuit produce a driving power to drive a load according to feedback detection signal.Feedback sense circuit comprises a computing change-over circuit and a signal limitations circuit.Computing change-over circuit produces feedback detection signal according to a level that couples a tested point of load, and wherein computing change-over circuit has an operational amplifier, and operational amplifier couples tested point with the size of the level adjustment feedback detection signal of corresponding tested point.Signal limitations circuit couples computing change-over circuit, in order to control the scope of feedback detection signal.
The present invention also provides another kind of feedback sense circuit, is applicable to provide a feedback detection signal, makes a change-over circuit produce a driving power to drive a load according to feedback detection signal.Feedback sense circuit comprises a computing change-over circuit and a signal limitations circuit.Computing change-over circuit produces feedback detection signal according to a level of a tested point, and wherein computing change-over circuit has an operational amplifier, and operational amplifier couples tested point with the size of the level adjustment feedback detection signal of corresponding tested point.Signal limitations circuit couples computing change-over circuit, and determine whether to control feedback detection signal according to a pulse signal, wherein a level of signal limitations circuit limit feedback detection signal when pulse signal is positioned at first logic state, at a predetermined level, is positioned at the not level of limit feedback detection signal of one second logic state at pulse signal.
Above general introduction and ensuing detailed description are all exemplary in nature, are in order to further illustrate claim of the present invention.And relevant other objects and advantages of the present invention are set forth the explanation follow-up and accompanying drawing.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of traditional optical coupling feedback circuit;
Fig. 2 is the circuit diagram of the light-emitting diode pulse light modulation system of traditional integrating power supply system architecture;
Fig. 3 is the circuit block diagram of feedback sense circuit of the present invention;
Fig. 4 is the circuit diagram that the feedback sense circuit of one first embodiment according to the present invention is applied to light-emitting diode pulse light modulation system;
Fig. 5 is the circuit diagram of the feedback sense circuit of one second embodiment according to the present invention;
Fig. 6 is the circuit diagram of the feedback sense circuit of one the 3rd embodiment according to the present invention;
Fig. 7 is the circuit diagram of the feedback sense circuit of one the 4th embodiment according to the present invention.
Description of reference numerals:
PC: optical coupler;
TL431: shunt regulator;
Vout: output voltage;
VD: voltage divider;
FB: feedback detection signal;
CN: compensating circuit;
VCC: system voltage;
LD: light-emitting diode (LED) module;
VLED: driving voltage;
M: transistor switch;
DIM: impulse width modulation and light adjusting signal;
D1: diode;
110,210,310,410,510: computing change-over circuit;
120,220,320,420,520: signal limitations circuit;
MP: the level of tested point;
Sd: feedback detection signal;
200: switching controller;
250: voltage conversion circuit;
VLED: driving voltage;
R, R1, R2, R4, R5, R6: resistance;
D1: diode;
I: controlled current source;
PC: optical coupler;
M1, M2, M3, M4: transistor;
PWM: pulse-width signal;
I1, I2: electric current;
Vr: reference voltage;
DIM: impulse width modulation and light adjusting signal;
M: transistor switch;
VD: voltage divider;
CN: compensating circuit;
VCC: system voltage;
LD: light-emitting diode (LED) module;
330,430: state control circuit;
340,440: inverter.
Embodiment
Fig. 3 is the circuit block diagram of feedback sense circuit of the present invention.Please refer to Fig. 3, feedback sense circuit comprises a computing change-over circuit 110 and a signal limitations circuit 120.Computing change-over circuit 110 produces a feedback detection signal Sd according to the level MP that couples a tested point of a load (not shown).Signal limitations circuit 120 couples computing change-over circuit 110, in order to control the scope of feedback detection signal Sd.For example: the maximum level of feedback detection signal Sd is reduced and/or minimum level raising, make to feed back detection signal Sd when feedback sense circuit is carried out state switching according to the level MP of tested point, feedback detection signal Sd need not started to adjust by maximum or minimum value, reaches the advantage of fast reaction speed so the adjusting range of computing change-over circuit 110 is dwindled.Or, also can be according to an impulse width modulation and light adjusting signal, when (OFF) turn-offed in representative, by a level of the direct limit feedback detection signal of feedback detection signal Sd Sd at a predetermined level.Therefore, feedback sense circuit of the present invention goes for providing feedback detection signal Sd to change-over circuit (not shown), make change-over circuit produce a driving power to drive load according to feedback detection signal Sd, and meet in the continuous switching of a few thing state and the system higher to the rate request of transient response.
Fig. 4 is the circuit diagram that the feedback sense circuit of one first embodiment according to the present invention is applied to light-emitting diode pulse light modulation system.Please refer to Fig. 4, for better understanding advantage of the present invention, the light-emitting diode pulse light modulation system shown in Fig. 2 of therefore take illustrates as basis.Certainly, feedback sense circuit of the present invention also can be applied to the different application environment such as linear load and the restriction that not illustrated by embodiment.In the present embodiment, feedback sense circuit comprises a computing change-over circuit 210 and a signal limitations circuit 220.Computing change-over circuit 210 is a shunt regulator, in order to produce a feedback detection signal Sd according to a level MP of a tested point.Feedback detection signal Sd reaches a switching controller 200, to control a voltage conversion circuit 250, produces driving voltage VLED.Signal limitations circuit 220 is coupled between computing change-over circuit 210 and resistance R, reaches the effect of the scope of limit feedback detection signal Sd in order to the maximum of limit feedback detection signal Sd.In the present embodiment, signal limitations circuit 220 comprises a Zener diode.When transistor switch M turn-offs, the level of the negative terminal of light-emitting diode (LED) module LD can raise.Now, diode D1 oppositely turn-offs and makes the level MP of tested point increase, computing change-over circuit 210 reduce flow into the electric current of cathode terminals and make to feed back detection signal Sd an electrical level rising until signal limitations circuit 220 lower than a puncture voltage of Zener diode, turn-off because of its cross-pressure.Compared to the level of the cathode terminal of the shunt regulator TL431 in Fig. 2, can rise to and approach system voltage VCC, the maximum of the feedback detection signal Sd of the present embodiment is subject to 220 restrictions of signal limiting circuit and reduces.The electrical level rising of feedback detection signal Sd can make switching controller 200 downgrade a power output of voltage conversion circuit 250.And when transistor switch M conducting, the level of the negative terminal of light-emitting diode (LED) module LD can decline.Now, the level MP that diode D1 conducting makes tested point also by least lower than system voltage VCC deduct a Zener diode puncture voltage one compared with low level, start to decline.Therefore, the amplitude of computing change-over circuit 210 required adjustment is dwindled and is reached the effect that improves transient response speed.
Fig. 5 is the circuit diagram of the feedback sense circuit of one second embodiment according to the present invention.Please refer to Fig. 5, feedback sense circuit comprises a computing change-over circuit 310, a signal limitations circuit 320 and a state control circuit 330.Compared to the embodiment shown in Fig. 4, in the present embodiment, transistor switch M replaces with a controlled current source I.Computing change-over circuit 310 couples an optical coupler PC to produce a feedback detection signal Sd to reach buffer action.The transistor M2 that signal limitations circuit 320 comprises series connection and a resistance R 2, one end one resistance R couples computing change-over circuit 310, other end ground connection.The transistor M1 that state control circuit 330 comprises series connection and a resistance R 1, one end couples computing change-over circuit 310, other end ground connection.In the present embodiment, transistor can be that MOS field-effect pipe, double carrier transistor or other have the assembly of handoff functionality.
Conducting and the shutoff of the one transistor M2 of pulse-width signal pwm control signal limiting circuit 320 and the transistor M1 of state control circuit 330, and control controlled current source I by an inverter 340.When being low level, pulse-width signal PWM (calls the second logic state in the following text), controlled current source I provides a scheduled current to make a light-emitting diode (LED) module LD luminous, and transistor M1, M2 are signal limitations circuit 320 and the state control circuit 330 nothing effects of making of turn-offing simultaneously.Now, a voltage divider VD provides an electric current I 1 diode D1 that flows through.When pulse-width signal PWM is high level, (call the first logic state in the following text), controlled current source I stops providing electric current, and light-emitting diode (LED) module LD is extinguished.Now, transistor M2 conducting, the electric current of optical coupler PC of making to flow through increases and reduces the level of the feedback detection signal Sd producing, makes a change-over circuit (not shown) that receives feedback detection signal Sd reduce the power that exports light-emitting diode (LED) module LD to.Meanwhile, transistor M1 conducting, makes voltage divider VD that one electric current I 2 state control circuit 330 of flowing through is provided.Electric current I 2 can be set bigger or be slightly less than electric current I 1, and the state of computing change-over circuit 310 and the state of pulse-width signal PWM when the second logic state are approached, and is preferably set as electric current I 2 and equals electric current I 1.By state control circuit 330, when pulse-width signal PWM is positioned at the first logic state, this level having of a tested point while providing a virtual level not have state control circuit 330 to replace, closer to each other or equate while making the state of at least part of internal circuit of computing change-over circuit 310 be positioned at the first logic state and the second logic state with pulse-width signal PWM, and reach the advantage of fast reaction speed.
Fig. 6 is the circuit diagram of the feedback sense circuit of one the 3rd embodiment according to the present invention.Please refer to Fig. 6, at the present embodiment, a computing change-over circuit 410 comprises an operational amplifier and replaces the shunt regulator (generally speaking, also there is operational amplifier shunt regulator inside) in embodiment illustrated in fig. 5.Due to the compensation of carrying out FEEDBACK CONTROL that act as of compensating circuit CN, be not necessary circuitry, and do not need, in the applied environment of isolation, also without optical coupler, at the present embodiment, to be omitted at some.Feedback sense circuit comprises computing change-over circuit 410, a signal limitations circuit 420 and a state control circuit 430.The transistor M4 that signal limitations circuit 420 comprises series connection and a resistance R 4.State control circuit 430 comprises a voltage divider VD and a transistor M3.
When a pulse-width signal PWM is the second logic state, a controlled current source I provides a scheduled current to make a light-emitting diode (LED) module LD luminous, and transistor M3, M4 are signal limitations circuit 420 and the state control circuit 430 nothing effects of making of turn-offing simultaneously.One inverting terminal of the operational amplifier in computing change-over circuit 410 couples a negative terminal of light-emitting diode (LED) module LD by a diode D1, one not inverting terminal receive a reference voltage Vr, to export accordingly a feedback detection signal Sd.Now, signal limitations circuit 420 turn-offs the not level of limit feedback detection signal Sd because of transistor M4.When pulse-width signal PWM is the first logic state, controlled current source I stops providing electric current, makes light-emitting diode (LED) module LD extinguish the electrical level rising of light-emitting diode (LED) module LD negative terminal.Now, transistor M3 conducting, make the voltage divider VD effect in state control circuit 430 that the level of the inverting terminal of the operational amplifier in computing change-over circuit 410 is limited in to a level, making diode D1 is anti-phase shutoff the state that simultaneously maintains the operational amplifier in computing change-over circuit 410.Meanwhile, also conducting of transistor M4, by the dividing potential drop effect of resistance R 4, R5, is also limited in a predetermined level by the level of feedback detection signal Sd, and change-over circuit (not shown) is reduced to be provided to the power of light-emitting diode (LED) module LD.By above-mentioned circuit framework, closer to each other compared with prior art when the state of computing change-over circuit 410 and pulse-width signal PWM are positioned at the first logic state and the second logic state, and reach the advantage of fast reaction speed.
Fig. 7 is the circuit diagram of the feedback sense circuit of one the 4th embodiment according to the present invention.Please refer to Fig. 7, a computing change-over circuit 510 of the present embodiment comprises an operational amplifier, and a signal limitations circuit 520 comprises a transistor, by an optical coupler PC, couples computing change-over circuit 510.One light-emitting diode (LED) module LD is subject to the driving voltage VLED that a change-over circuit (not shown) produces to drive luminous.One controlled current source I provides according to an impulse width modulation and light adjusting signal DIM or stops providing the electric current light-emitting diode (LED) module LD that flows through.One voltage divider VD couples a system voltage VCC by a resistance R 6, and in order to the not inverting terminal of a voltage division signal to the operational amplifier in computing change-over circuit 510 to be provided, and an inverting terminal of operational amplifier receives a reference voltage Vr.An anode of one diode D1 couples the not inverting terminal of operational amplifier, and negative terminal couples a negative terminal of light-emitting diode (LED) module LD.Computing change-over circuit 510 couples optical coupler PC, to produce a feedback detection signal Sd.
When impulse width modulation and light adjusting signal DIM is high level, controlled current source I provides a scheduled current to make light-emitting diode (LED) module LD luminous.Now the negative terminal current potential of light-emitting diode (LED) module LD is compared with low and make diode D1 conducting and drag down the current potential of voltage divider VD dividing point.Now the level of an output signal of the operational amplifier of computing change-over circuit 510 declines, and makes the transistor turns in signal limitations circuit 520.Optical coupler PC produces feedback detection signal Sd according to the level of the output signal of operational amplifier.When impulse width modulation and light adjusting signal DIM is low level, controlled current source I stops providing scheduled current that light-emitting diode (LED) module LD is extinguished.Now the negative terminal current potential of light-emitting diode (LED) module LD is compared with high and diode D1 is oppositely turn-offed.Now, the resistance of the level of the not inverting terminal of the operational amplifier of computing change-over circuit 510 in resistance R 6 and voltage divider VD is determined but level when luminous higher than light-emitting diode (LED) module LD, makes the electrical level rising of the output signal of operational amplifier.And a transistorized control end in signal limitations circuit 520 couples resistance R 6, therefore the resistance that the level of control end also can be in resistance R 6 and voltage divider VD and determining, the potential rise that makes signal limitations circuit 520 and the tie point of optical coupler PC is to stopping during with voltage divider VD tie point one predetermined voltage difference lower than resistance R 6.Namely, when the output signal of computing change-over circuit 510 is during higher than a predetermined control level, transistor in signal limitations circuit 520 now turn-offs and the maximum of restricting signal limiting circuit 520 and the current potential of the tie point of optical coupler PC, thereby has limited the scope of feedback detection signal Sd.
Finally it should be noted that: each embodiment, only in order to technical scheme of the present invention to be described, is not intended to limit above; Although the present invention is had been described in detail with reference to aforementioned each embodiment, those of ordinary skill in the art is to be understood that: its technical scheme that still can record aforementioned each embodiment is modified, or some or all of technical characterictic is wherein equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution depart from the scope of various embodiments of the present invention technical scheme.
Claims (9)
1. a feedback sense circuit, is applicable to provide a feedback detection signal, makes a change-over circuit produce a driving power to drive a load according to this feedback detection signal, it is characterized in that, this feedback sense circuit comprises:
One computing change-over circuit, according to a level that couples a tested point of this load, produce this feedback detection signal, wherein this computing change-over circuit has an operational amplifier, and this operational amplifier couples this tested point this level that should tested point is adjusted to the size of this feedback detection signal; And
One signal limitations circuit, couples this computing change-over circuit, in order to control the scope of this feedback detection signal.
2. feedback sense circuit according to claim 1, is characterized in that, this computing change-over circuit is a shunt regulator.
3. feedback sense circuit according to claim 1 and 2, is characterized in that, this signal limitations circuit comprises a Zener diode.
4. feedback sense circuit according to claim 1 and 2, is characterized in that, this signal limitations circuit comprises a transistor switch, an output signal of this computing change-over circuit during higher than a predetermined control level this transistor switch turn-off.
5. a feedback sense circuit, is applicable to provide a feedback detection signal, makes a change-over circuit produce a driving power to drive a load according to this feedback detection signal, it is characterized in that, this feedback sense circuit comprises:
One computing change-over circuit, according to a level of a tested point, produce a feedback detection signal, wherein this computing change-over circuit has an operational amplifier, and this operational amplifier couples this tested point this level that should tested point is adjusted to the size of this feedback detection signal; And
One signal limitations circuit, couple this computing change-over circuit, and determine whether to control this feedback detection signal according to a pulse signal, the level that wherein this signal limitations circuit limits this feedback detection signal when this pulse signal is positioned at first logic state, at a predetermined level, is positioned at this pulse signal this level that one second logic state does not limit this feedback detection signal.
6. feedback sense circuit according to claim 5, it is characterized in that, also comprise a state control circuit, be coupled to this computing change-over circuit, this state control circuit, when this pulse signal is positioned at this first logic state, provides a virtual level to replace this level of this tested point.
7. according to the feedback sense circuit described in claim 5 or 6, it is characterized in that, this signal limitations circuit comprises a transistor switch, this transistor switch switches according to this pulse signal, makes this level of this feedback detection signal when this pulse signal is positioned at this first logic state, be limited in this predetermined level.
8. according to the feedback sense circuit described in claim 5 or 6, it is characterized in that, this computing change-over circuit is a shunt regulator.
9. feedback sense circuit according to claim 6, it is characterized in that, this state control circuit comprises a transistor switch, and this transistor switch switches according to this pulse signal, makes this state control circuit that this virtual level is provided when this pulse signal is positioned at this first logic state.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210235233.0A CN103546143B (en) | 2012-07-09 | 2012-07-09 | Feedback sense circuit |
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| CN201210235233.0A CN103546143B (en) | 2012-07-09 | 2012-07-09 | Feedback sense circuit |
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| CN103546143A true CN103546143A (en) | 2014-01-29 |
| CN103546143B CN103546143B (en) | 2016-05-18 |
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| US20100283322A1 (en) * | 2009-05-06 | 2010-11-11 | Polar Semiconductor, Inc. | Multiple output power supply |
| CN101902855A (en) * | 2009-05-27 | 2010-12-01 | 登丰微电子股份有限公司 | LED driving circuit and backlight module |
| US20100327761A1 (en) * | 2009-06-30 | 2010-12-30 | Microsemi Corporation | Integrated backlight control system |
| CN102077692A (en) * | 2008-06-30 | 2011-05-25 | 艾沃特有限公司 | Led driver with multiple feedback loops |
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2012
- 2012-07-09 CN CN201210235233.0A patent/CN103546143B/en not_active Expired - Fee Related
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1971352A (en) * | 2005-10-26 | 2007-05-30 | 三星电子株式会社 | Touch sensible display device and method thereof |
| US20080106216A1 (en) * | 2006-10-18 | 2008-05-08 | Advanced Analog Technology, Inc. | Dimming method for light-emitting diodes |
| CN102077692A (en) * | 2008-06-30 | 2011-05-25 | 艾沃特有限公司 | Led driver with multiple feedback loops |
| CN201307951Y (en) * | 2008-11-12 | 2009-09-09 | 登丰微电子股份有限公司 | Light-emitting diode drive circuit |
| CN101772237A (en) * | 2008-12-31 | 2010-07-07 | 凹凸电子（武汉）有限公司 | Circuit for controlling light sources, method and display system |
| US20100283322A1 (en) * | 2009-05-06 | 2010-11-11 | Polar Semiconductor, Inc. | Multiple output power supply |
| CN101902855A (en) * | 2009-05-27 | 2010-12-01 | 登丰微电子股份有限公司 | LED driving circuit and backlight module |
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