CN102695325B - Drive circuit and feedback control circuit - Google Patents
Drive circuit and feedback control circuit Download PDFInfo
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- CN102695325B CN102695325B CN201110161891.5A CN201110161891A CN102695325B CN 102695325 B CN102695325 B CN 102695325B CN 201110161891 A CN201110161891 A CN 201110161891A CN 102695325 B CN102695325 B CN 102695325B
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Abstract
The invention provides a driving circuit and a control circuit. The power supply circuit is used to provide a power to drive a load. The transistor unit has at least one load coupling end for coupling with the load so as to adjust a current flowing through the load. The feedback control circuit controls the power provided by the power supply circuit according to the potential of at least one load coupling end. The feedback control circuit comprises an error amplifying circuit and a feedback control switch, wherein the error amplifying circuit generates an error amplifying signal according to the potential of at least one load coupling end, and the feedback control switch is coupled to an output end of the error amplifying circuit and switches between a conducting state and a closing state according to a dimming signal. The invention can return to the stable state more quickly in the dimming process, so that the dimming is more accurate.
Description
Technical field
The present invention relates to a kind of drive circuit and control circuit, espespecially relate to a kind of drive circuit and control circuit of tool voltage stabilization and current stabilization function.
Background technology
At present, it is maximum for accounting for 14% with electric power in the energy that the whole world is annual, and on electricity usage proportion, illumination proportion is up to 22%.Therefore, under the trend of present stage whole world carbon reduction, the impact of illumination occupies very important status.
Lighting source common is now based on incandescent lamp and fluorescent lamp.Although incandescent lamp is with low cost, but because there is the shortcoming of highly energy-consuming, low luminous efficiency, high heating, do not meet the trend of present stage whole world carbon reduction.Fluorescent tube, with glass manufacture, is equipped with socket to connect the position of power supply and fixing fluorescent tube at two ends.Different from incandescent lamp, fluorescent tube must be provided with ballast (being also called " stabilizer "), coordinates the instantaneous pressure producing and allow gas occur to ionize to light fluorescent lamp with starter.The advantage of fluorescent lamp is the enough low and luminous efficiencies of cost enough well.Such as, but this product also uses problem with some: flicker, preheating etc.The flicker frequency of fluorescent lamp is relevant with the frequency of driving voltage.Although human eye not easily directly perceives the flicker of fluorescent lamp, these flickers can produce fanning effect (Fan Effect) in some environments, and cause restriction, the impact of some applied environments.Brightness changes at the beginning of the preheating of fluorescent lamp can cause lighting and after using a period of time.So the characteristics such as long service life, the luminous efficiency of light-emitting diode are high, brightness stability is fast are regarded as the next luminescence of generation, the main source of illumination.
The applicable lighting field of light-emitting diode is quite wide, comprises the backlight module etc. of room lighting, outdoor lighting, advertising signboard, electronic product.And in above-mentioned application, behave the in the past high cost that denounces and heat dissipation problem of LED backlight improves just fast, overall permeability will continue quick raising future.And replace lighting source now one by one along with light-emitting diode; how suitable driving as light source light-emitting diode and suitable protection is provided, make light-emitting diode can play the advantage of its characteristic and improve the safety on using and become problem important now.
Summary of the invention
For the luminescence that light-emitting diode can be made to provide stable, corresponding different type of drive, the present invention, in the mode of Current Control and Voltage Feedback, makes the luminescence that light-emitting diode can provide stable.And for avoiding LED driving circuit to use any circuit problem that may meet with, the present invention provides defencive function in addition, when being enough to the problem generation affecting circuit normal operation, provides protection with the further damage avoiding circuit.
For reaching above-mentioned purpose, the invention provides a kind of drive circuit, comprising a power supply circuit, a transistor unit and a feedback control circuit.Power supply circuit system is in order to provide an electric power to drive a load.Transistor unit has at least one load coupled end in order to couple load, to adjust the size of current flowing through load.The electric power size that feedback control circuit provides according to the control of Electric potentials power supply circuit of at least one load coupled end.Wherein, feedback control circuit comprises an error amplifying circuit and a feedback control switch, error amplifying circuit produces an error amplification signal according to the current potential of at least one load coupled end, and the output that feedback control switch is coupled to error amplifying circuit switches between a conducting state and a closed condition according to a dim signal.
Present invention provides another kind of drive circuit, comprise a power supply circuit, a transistor unit and a feedback control circuit.Power supply circuit system is in order to provide an electric power to drive a load.Transistor unit has at least one load coupled end in order to couple load, to adjust the size of current flowing through load.The electric power size that feedback control circuit provides according to the control of Electric potentials power supply circuit of at least one load coupled end.Wherein, feedback control circuit comprises a feedback signal and produces circuit and a feedback control switch, feedback signal produces circuit by feedback control switch coupling transistors unit, to produce a feedback signal according to the current potential of at least one load coupled end, feedback control switch is coupled to feedback signal generation circuit and switches between a conducting state and a closed condition according to a dim signal.
Present invention provides a kind of control circuit, in order to control a power-switching circuit, with the output of stabilized power supply change-over circuit.Control circuit comprises an electric capacity, a charhing unit, discharge cell coupling capacitance, a feedback control unit and a duty ratio adjustment unit.Charhing unit has one first current source coupling capacitance, in order to charge to electric capacity.Discharge cell coupling capacitance, in order to discharge to electric capacity.Feedback control unit is according to representing a feedback signal of output state to control charhing unit to capacitor charging.Duty ratio adjustment unit system is in order to produce a control signal, and the duty ratio of Voltage Cortrol control signal according to electric capacity.Wherein, at least wherein one of charhing unit and discharge cell exported size of current is adjusted according to feedback signal.
In one embodiment of this invention; feedback control circuit is when feedback control switch is in conducting state; judge the current potential of these load coupled ends arbitrary whether lower than one first predetermined potential value or higher than one second predetermined potential value time; power supply circuit is stopped to provide electric power if then award control circuit, to reach the effect of protection drive circuit.
Above general introduction and ensuing detailed description are all exemplary in nature, are to further illustrate claim of the present invention.And other objects and advantages for the present invention, set forth in follow-up explanation and accompanying drawing.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of the drive circuit according to one first preferred embodiment of the present invention.
Fig. 2 is the circuit diagram of the drive circuit according to one second preferred embodiment of the present invention.
Fig. 3 is the circuit diagram of the drive circuit according to of the present invention 1 the 3rd preferred embodiment.
Fig. 4 is the circuit diagram of the drive circuit according to of the present invention 1 the 4th preferred embodiment.
Fig. 5 is the circuit diagram of controlled current flow circuit according to a preferred embodiment of the present invention.
Main element symbol description:
100,200: feedback control circuit
102: error amplifying circuit
104: compensating circuit
106: feedback control switch
110,210: control circuit of duty ratio
112,212: feedback control unit
114: charge switch
116: electric capacity
120,220: pulse-width regulating device
130: driver element
150: load
160,260: power supply circuit
170,270: transistor unit
172: current control circuit
174: transistor
203: timing circuit
208: overvoltage comparator
215: second switch
217: the three switches
222: comparator
224:SR trigger
230: driver element
235: protected location
245: the second extreme voltage circuit for detecting
240: the first extreme voltage circuit for detecting
250: light-emitting diode (LED) module
BD: bridge rectifier
C: output capacitance
D, D1, D2: rectifier diode
DIM: dim signal
DS1 ~ DSN: load coupled end
Fault: rub-out signal
FB: feedback signal
FB1: the first feedback signal
FB2: the second feedback signal
FB3: the three feedback signal
I1: the first current source
I2: the second current source
I3: the three current source
Ise: current sense signal
L: inductance
Prot: guard signal
OVP: overvoltage protection signal
Q: output
R: reset end
Ri: current sense resistance
S: setting end
S1: too low guard signal
S2: pulse-width modulation signal
Sc: control signal
Ser: feedback processing signal
SW: transistor
V: reference voltage signal
VAC: alternating current input power supplying
VCC: driving power
Vi: reference voltage
Vin: input power
Vi1-ViN: reference voltage
Vout: output voltage
Vr1: the first reference voltage signal
Vr2: the second reference voltage signal
Vr3: the three reference voltage signal
T: transformer
Ia, Ib, Ic: current source
Is: electric current
Ma, Mb, Mc: current switch
Sa, Sb, Sc: control signal
Vra, Vrb, Vrc: comparison reference signal
Coa, Cob, Coc: comparator
FB-Vr: definitely level is poor
Embodiment
Referring to Fig. 1, is the circuit diagram of the drive circuit of one first preferred embodiment according to the present invention.Drive circuit comprises a feedback control circuit 100, transistor unit 170 and a power supply circuit 160, in order to drive a load 150.In the present embodiment, load 150 is a light-emitting diode (LED) module, has several light-emitting diodes of series connection bunchiness.Power supply circuit 160 couples an input power Vin, to be changed by the electric power of input power Vin (such as: boosting or step-down) according to a control signal Sc, to export an output voltage Vout to drive the light-emitting diode (LED) module of load 150 luminous.In this enforcement, power supply circuit 160 is the DC boosting change-over circuit that always circulates, and comprises an inductance L, a transistor SW, an a rectifier diode D and output capacitance C.One end of inductance L couples input power Vin, one end of other end coupling transistors SW, and the other end ground connection of transistor SW.One end of output capacitance C couples the tie point of inductance L and transistor SW, other end ground connection by rectifier diode D.Transistor unit 170 is a current control circuit, couples load 150 flows through load 150 size of current with adjustment.Transistor unit 170 comprises transistor 174 and a current control circuit 172.Transistor 174 has a current feedback terminal, a control end and a load coupled end, and wherein current feedback terminal couples a current sense resistance Ri, and load coupled end couples load 150 and control end couples the output of current control circuit 172.Current control circuit 172 is an amplifier, its noninverting reception one reference voltage Vi, the current feedback terminal of end of oppisite phase coupling transistors 174, to control the state of transistor 174 according to the current potential of current feedback terminal and reference voltage Vi, namely control the equivalent resistance of transistor 174, regulation and control flow through the size of current of transistor 174 by this.Current control circuit 172 receives a dim signal DIM simultaneously, when dim signal DIM represents " ON " (light-emitting diode (LED) module representing load 150 is luminous), current control circuit 172 as above regulates and controls to flow through the size of current of transistor 174, and when dim signal DIM represents " OFF " (light-emitting diode (LED) module representing load 150 stops luminous), close transistor 174.
The load coupled end of transistor 174 in feedback control circuit 100 coupling transistors unit 170, to receive the feedback signal FB representing transistor unit 170 cross-pressure, namely according to the electric power size that the control of Electric potentials power supply circuit 160 of load coupled end provides.Feedback control circuit 100 comprises control circuit of duty ratio 110, error amplifying circuit 102, compensating circuit 104 and a feedback control switch 106.Error amplifying circuit 102 produces an error amplification signal to compensating circuit 104 according to a feedback signal FB and reference voltage signal Vr and stores to produce a feedback processing signal Ser.Feedback control switch 106 is coupled between the reference-junction compensation circuit 104 of error amplifying circuit 102, and switches between a conducting state and a closed condition according to a dim signal DIM.When dim signal DIM represents " ON ", feedback control switch 106 is in conducting state to transmit error amplification signal to this compensating circuit 104 to produce feedback processing signal Ser.When dim signal DIM represents " OFF ", feedback control switch 106 is in closed condition to stop transmitting error amplification signal to this compensating circuit 104, makes electric capacity 116 maintain the level of feedback processing signal Ser.Control circuit of duty ratio 110 comprises pulse-width regulating device 120 and a driver element 130.Pulse-width regulating device 120 can be a comparator, and its end of oppisite phase receives a ramp signal, and non-oppisite phase end couples compensating circuit 104 to receive feedback processing signal Ser, and produces a pulse-width modulation signal S2 accordingly to driver element 130.Driver element 130 receives dim signal DIM and pulse-width modulation signal S2.When dim signal DIM represents " ON ", driver element 130 produces conducting and the closedown that control signal Sc controls the transistor SW in power supply circuit 160, to adjust the size that power supply circuit 160 provides electric power according to pulse-width modulation signal S2.When dim signal DIM represents " OFF ", driver element 130 controls power supply circuit 160 to be stopped providing electric power.
To sum up illustrate, when dim signal DIM represents " OFF ", the transistor 174 in transistor unit 170 is closed, and flows through electric current and avoid continuing to consume the electric power stored by output capacitance C to stop load 150.Now, power supply circuit 160 stops providing electric power, therefore makes voltage during output voltage Vout maintenance stable operation constant.In addition, the current potential of the feedback control switch 106 in feedback control circuit 100 in time being now in closed condition and making the level of feedback processing signal Ser also maintain stable operation is constant.And when dim signal DIM transfers representative " ON " to, load 150 can flow through size of current during stable operation at once, and driver element 130 also can provide the control signal Sc of the duty ratio (Duty Cycle) when having stable immediately.Compared to LED driving circuit in the past, drive circuit of the present invention can return back to stable state sooner in dimming process, makes light modulation more accurate.
Referring to Fig. 2, is the circuit diagram of the LED driving circuit of one second preferred embodiment according to the present invention.Relatively the present embodiment and the embodiment shown in the first figure, its Main Differences is that error amplifying circuit 102, compensating circuit 104 in feedback control circuit 100 and a feedback control switch 106 produce circuit replacement with feedback signal, is described as follows.
Feedback control circuit 100 comprises control circuit of duty ratio 110, feedback control unit 112, feedback control switch 106 and a feedback signal produces circuit, and wherein feedback signal generation circuit comprises a charhing unit, a discharge cell and an electric capacity 116.Charhing unit has one first current source I1 and charge switch 114, a first current source I1 by charge switch 114 coupling capacitance 116 to provide a charging current to charge to electric capacity 116.Discharge cell has one second current source I2 coupling capacitance 116, provides a discharging current to discharge to electric capacity 116.In the present embodiment, feedback control unit 112 is a comparator, and its non-oppisite phase end receives a reference voltage signal Vr, and end of oppisite phase receiving feedback signals FB is to control conducting and the closedown of charge switch 114 accordingly.Feedback control switch 106 coupling capacitance 116 to the first current source I1 and the second current source I2, and switch between a conducting state and a closed condition according to a dim signal DIM.When dim signal DIM represents " ON ", feedback control switch 106 is in conducting state makes the first current source I1 and the second current source I2 discharge to electric capacity 116 and to charge, and makes the current potential of electric capacity 116 according to feedback signal FB adjustment to produce a feedback processing signal Ser.When dim signal DIM represents " OFF ", feedback control switch 106 is in closed condition to stop the first current source I1 and the second current source I2 to electric capacity 116, makes electric capacity 116 maintain the current potential of now feedback processing signal Ser.
Therefore, the drive circuit of the present embodiment can maintain the level of feedback processing signal Ser as drive circuit as shown in Figure 1 when dim signal DIM represents " OFF ", and when dim signal DIM transfers representative " ON " to, make driver element 130 can provide the control signal Sc of duty ratio when having stable immediately.Therefore the drive circuit of the present embodiment also has the accurate advantage of light modulation.
Drive circuit of the present invention is except the DC-DC voltage up converting circuit in above-described embodiment, and other have the power supply circuit of direct voltage output function, such as: inverse-excitation type change-over circuit, forward formula change-over circuit etc.Following elder generation is with the explanation of forward formula change-over circuit.
Referring to Fig. 3, is the circuit diagram of the drive circuit according to of the present invention 1 the 3rd preferred embodiment.LED driving circuit comprises a feedback control circuit 200, transistor unit 270 and a power supply circuit 260, in order to drive a light-emitting diode (LED) module 250.Light-emitting diode (LED) module 250 has several light-emitting diode string and these light-emitting diode strings are connected in parallel to each other.Power supply circuit 260 couples an alternating current input power supplying VAC by a bridge rectifier BD, to be changed by the electric power of alternating current input power supplying VAC according to a control signal Sc, to drive light-emitting diode (LED) module 250 luminous.In this enforcement, power supply circuit 260 is a forward formula change-over circuit, comprises a transformer T, a transistor SW, rectifier diode D1, D2 and an output capacitance C.One end of the primary side of transformer T couples stream input power VAC, one end of other end coupling transistors SW, and the other end of transistor SW is by a current sense grounding through resistance.One end of output capacitance C couples the primary side of transformer T and other end ground connection by rectifier diode D1, D2.
Predetermined electric current is all flow through in order to ensure the arbitrary light-emitting diode in light-emitting diode (LED) module 250, several load coupled end DS1 ~ DSN of transistor unit 270, couple the several light-emitting diode strings in light-emitting diode (LED) module 250 one to one, make the electric current of several light-emitting diode string all be stable at predetermined current value.In the present embodiment, each in several load coupled end DS1 ~ DSN all couples a current control circuit, and current control circuit comprises a transistor and a current control circuit as previous embodiment.During actual enforcement, transistor unit 270 can use current mirror or other are using transistor as the current source controlled, and is not limited to the circuit that the present embodiment is carried.Owing to often going here and there, light-emitting diode crossfire is not identical through the driving voltage needed for predetermined current value, causes the voltage levels of several load coupled end DS1 ~ DSN different.For the load coupled end DS1 ~ DSN making transistor unit 270 all can normal running, namely the electric current of controllable flow warp is predetermined current value, and the level of load coupled end DS1 ~ DSN must maintain one first predetermined potential value.For this reason, the present invention can increase by one first extreme voltage circuit for detecting 240, couples several load coupled end DS1 ~ DSN, and produces one first feedback signal FB1 according to potential minimum between load coupled end DS1 ~ DSN.First extreme voltage circuit for detecting 240 can comprise several diode, and its negative terminal respectively correspondence is coupled to several load coupled end DS1 ~ DSN, and its anode is connected to each other and be coupled to a driving power VCC by a resistance.So, except the diode corresponding to the load coupled end with potential minimum can except forward conduction, the cross-pressure on all the other diodes is not enough and cannot conducting, makes the current potential of the first feedback signal FB1 be the forward bias that the potential minimum of load coupled end adds diode.In addition, the reference voltage Vi1-ViN that current control circuit in transistor unit 270 receives can not be identical, with the light-emitting diode of the different current drive requirements of correspondence, certain reference voltage Vi1-ViN also can be identical, makes the arbitrary light-emitting diode in light-emitting diode (LED) module 250 all flow through identical electric current.
Feedback control circuit 200 comprises a control circuit of duty ratio 210 and a feedback signal produces circuit.Feedback signal produces circuit and comprises a feedback control unit 212, and feedback control unit 212 can be a comparator, its non-oppisite phase end receives one first reference voltage signal Vr1, end of oppisite phase receives the signal be made up of the first feedback signal FB1 and the 3rd reference voltage signal Vr3, namely the level of the 3rd reference voltage signal Vr3 deducts the level of the first feedback signal FB1, and wherein the level of the 3rd reference voltage signal Vr3 is higher than the level of the first reference voltage signal Vr1.As level arbitrary lower than the first predetermined potential value of load coupled end DS1 ~ DSN, feedback control unit 212 is made to produce a feedback processing signal Ser lower than the level of the first reference voltage signal Vr1 the level of the signal that the end of oppisite phase of feedback control unit 212 is received.Control circuit of duty ratio 210 comprises set-reset flip-floop 224 and a driver element 230.The end R that resets of set-reset flip-floop 224 receives a periodic pulse signal, and setting end S receives feedback processing signal Ser.Therefore, when feedback control unit 212 produces feedback processing signal Ser, set-reset flip-floop 224 will be triggered and produce pulse-width modulation signal S2 to driver element 230 by an output Q.Driver element 230 receives a dim signal DIM and pulse-width modulation signal S2, and transistor unit 270 also receives dim signal DIM simultaneously.When dim signal DIM represents " ON ", driver element 230 produces according to pulse-width modulation signal S2 conducting and the closedown that control signal Sc controls the transistor SW in power supply circuit 260, provide electrical power to adjust alternating current input power supplying VAC the size that power supply circuit 260 provides electric power, and transistor unit 270 also makes power supply circuit 260 supply electric power to light-emitting diode (LED) module 250 to drive it luminous.When dim signal DIM represents " OFF ", the transistor SW that driver element 230 controls in power supply circuit 260 provides electrical power to power supply circuit 260 to stop alternating current input power supplying VAC, and transistor unit 270 also stops power supply circuit 260 to supply electric power to light-emitting diode (LED) module 250.And be avoid feedback control circuit 200 now to occur any possible erroneous judgement because receiving the first feedback signal FB1, feedback signal produces circuit also can comprise a feedback control switch 205, be coupled to the first extreme voltage circuit for detecting 240 and feedback control unit 212, close when dim signal DIM represents " OFF ".Therefore the level that the level of the 3rd reference voltage signal Vr3 deducts the first feedback signal FB1 is not less than the level of the first reference voltage signal Vr1, and now feedback control unit 212 can not output feedack processing signals Ser.
Because the transistor in transistor unit 270 has withstand voltage restriction, the current potential arbitrary as load coupled end DS1 ~ DSN is damaged higher than causing transistor unit 270 during withstand voltage.Such as: when light-emitting diode string open circuit arbitrary in light-emitting diode (LED) module 250, cause feedback control circuit 200 constantly to promote the output voltage of power supply circuit 260 to attempt the load coupled terminal potential of correspondence to be promoted to scheduled voltage, the load coupled terminal potential that other light-emitting diode strings now can be caused corresponding is too high; Or, when part light-emitting diode short circuit in a certain light-emitting diode string, make that the cross-pressure on the light-emitting diode string of short circuit reduces and the load coupled terminal potential that causes this light-emitting diode string corresponding is too high.For avoiding the problems referred to above, can increase by one second extreme voltage circuit for detecting 245, coupling several load coupled end DS1 ~ DSN, and produce one second feedback signal FB2 according to maximum potential between load coupled end DS1 ~ DSN.Second extreme voltage circuit for detecting 245 can comprise several diode, and its anode respectively correspondence is coupled to several load coupled end DS1 ~ DSN, and its negative terminal is connected to each other and by a grounding through resistance.Feedback control circuit 200 also comprises an overvoltage comparator 208, and non-oppisite phase end receives the second feedback signal FB2, and end of oppisite phase receives one second reference voltage signal Vr2.When the current potential of the second feedback signal FB2 is higher than the second reference voltage signal Vr2, represent one of them level of load coupled end DS1 ~ DSN higher than one second predetermined potential value, now overvoltage comparator 208 is by output one overvoltage protection signal OVP.
In addition, when circuit normal operation, the current potential of several load coupled end DS1 ~ DSN all can maintain scheduled voltage or on.When the current potential of arbitrary load coupled end cannot go up to scheduled voltage lower than scheduled voltage, then represent circuit abnormality.But, when circuit is in the first or dimming process started, also will temporarily make the current potential of several load coupled end DS1 ~ DSN lower than scheduled voltage.For avoiding erroneous judgement and get rid of foregoing circuit extremely simultaneously; can increase by a timing circuit 203 in feedback control circuit 200 and couple feedback control unit 212; when the first feedback signal FB1 continues to reach a predetermined period of time lower than the first reference voltage signal Vr1; namely, when the lasting output high levle of feedback control unit 212 reaches predetermined period of time, timing circuit 203 exports a too low guard signal S1.Certainly, timing circuit 203 also can receive an enabling signal or a dim signal, and to decide the time point that timing starts according to enabling signal or dim signal, wherein enabling signal is represent the signal that drive circuit starts startup.And due to the electric power supply capacity of power supply circuit different along with the design of different circuit, the length of required predetermined period of time can be caused different.In order to can various circuit design be coordinated, if during feedback control circuit 200 single integrated circuit of the present invention, additionally can increase by a setting pin position, set above-mentioned predetermined period of time by outer meeting resistance or electric capacity (not shown).
Feedback control circuit 200 also comprises a protected location 235, couples timing circuit 203, overvoltage comparator 208 and driver element 230.In time receiving overvoltage protection signal OVP and too low guard signal S1 arbitrary, export a guard signal Prot and control driver element 230 reaches protection function to stop generation control signal Sc.In addition, protected location 235 can also the current sense signal Ise that produces of received current detecting resistance.When current sense signal Ise continues low level more than a Preset Time, there is open circuit in the circuit representing the input of power supply circuit 260, and protected location 235 also exportable guard signal Prot stops producing control signal Sc to control driver element 230.Or when current sense signal Ise is more than an overcurrent protection value; there is short circuit in the circuit representing the input of power supply circuit 260; now protected location 235 can export a rub-out signal Fault; to notify that the circuit of prime is stopped power supply to LED driving circuit, more element is caused to damage to avoid short circuit.
Referring to Fig. 4, is the circuit diagram of the LED driving circuit according to of the present invention 1 the 4th preferred embodiment.Relatively the present embodiment and the embodiment shown in the 3rd figure, its Main Differences is that power supply circuit 260 is inverse-excitation type change-over circuit, and the feedback controling mode of feedback control circuit 200 is also not identical, is described as follows.
Power supply circuit 260 couples an alternating current input power supplying VAC by a bridge rectifier BD, to be changed by the electric power of alternating current input power supplying VAC according to a control signal Sc, to drive light-emitting diode (LED) module 250 luminous.In this enforcement, power supply circuit 260 is an inverse-excitation type change-over circuit, comprises a transformer T, a transistor SW, an a rectifier diode D and output capacitance C.One end of the primary side of transformer T couples stream input power VAC, one end of other end coupling transistors SW, and the other end of transistor SW is by a current sense grounding through resistance.One end of output capacitance C couples the primary side of transformer T and other end ground connection by rectifier diode D.
Feedback control circuit 200 comprises a control circuit of duty ratio 210 and a feedback signal produces circuit.Feedback signal produces circuit and comprises feedback control unit 212, charhing unit, a discharge cell and an electric capacity 216, to produce a feedback processing signal Ser.Charhing unit has one first current source I1, one the 3rd current source I3 and the 3rd switch 217.First current source I1 coupling capacitance 216 charges to electric capacity 216 to provide a basic charging current, and the 3rd current source I3 is charged to electric capacity 216 to provide a charging current by the 3rd switch 217 coupling capacitance 216.Discharge cell has one second current source I2 and second switch 215, a second current source I2 by second switch 215 coupling capacitance 216, discharges to electric capacity 216 to provide a discharging current.Wherein, the size of current of the first current source I1 is less than the size of current of the second current source I2 and the 3rd current source I3.Feedback control unit 212 can be a comparator, and its end of oppisite phase receives one first reference voltage signal Vr1, and non-oppisite phase end receives the first feedback signal FB1 to control conducting and the closedown of second switch 215 accordingly.When level lower than the first reference voltage signal Vr1 of the level of the first feedback signal FB1, feedback control unit 212 exports low level signal to close second switch 215.Now the first current source I1 charges to electric capacity 216 voltage improving electric capacity 216.When level higher than the first reference voltage signal Vr1 of the level of the first feedback signal FB1, feedback control unit 212 exports high levle signal with conducting second switch 215, second current source I2 is discharged to electric capacity 216, and the first current source I1 charge simultaneously to electric capacity 216.Due to and the electric current of the first current source I1 is less than the electric current of the second current source I2, now the voltage of electric capacity 216 will reduce.Control circuit of duty ratio 210 comprises pulse-width regulating device 220 and a driver element 230.Pulse-width regulating device 220 comprises comparator 222 and a set-reset flip-floop 224.The non-oppisite phase end coupling capacitance 216 of comparator 222 to receive feedback processing signal Ser, end of oppisite phase received current detection signal Ise.One clock signal of the setting end S receive periodic of set-reset flip-floop 224, and reset end R couple comparator 222.When set-reset flip-floop 224 is in time setting end S and receive clock signal, produce a pulse-width modulation signal S2 to driver element 230 by output Q.Driver element 230 receives a pulse-width modulation signal S2 and dim signal DIM, to produce a control signal Sc accordingly with the transistor SW of turn-on power supply circuit 260.When the electric current flowing through transformer T primary side rises the voltage quasi position making the level of current sense signal Ise higher than electric capacity 216, the signal that comparator 222 exports high levle makes set-reset flip-floop 224 be reset, now driver element 230 stops producing control signal Sc, now the transistor SW of power supply circuit 260 closes, and makes the energy being stored in transformer T be sent to the primary side of power supply circuit 260 to provide driven by power light-emitting diode (LED) module 250 luminous.
In order at the beginning of circuit start or dimming process process, the voltage of electric capacity 216 first can rise the transient response speed promoting feedback control circuit 200 fast.Feedback control circuit 200 promotes circuit 204 by transient state and controls the 3rd switch 217.Transient state promotes circuit 204 and receives enabling signal EN and dim signal DIM, when receive enabling signal EN dim signal DIM by represent " OFF " convert " ON " to time, export high levle signal with conducting the 3rd switch 217, now the 3rd current source I3 and the first current source I1 charges to electric capacity 216 simultaneously and makes the voltage of electric capacity 216 increase fast.Transient state promotes circuit 204 and can set a scheduled time length or close the 3rd switch 217 according to the first feedback signal FB1, and namely the 3rd switch 217 cuts out after the conducting set time; Or close the 3rd switch 217 when minimum level arrives a predetermined level in the load coupled end DS1-DSN of transistor unit 270.And a feedback control switch 106 is coupled to electric capacity 216 and between charhing unit and discharge cell, when dim signal DIM represents " OFF ", feedback control switch 206 is in closed condition with the level of the feedback processing signal Ser maintaining electric capacity 216 and produce.
In addition, the overvoltage comparator 208 in the present embodiment, non-oppisite phase end system receives one the 3rd feedback signal FB3, to replace the second feedback signal FB2 of the 3rd figure illustrated embodiment.3rd feedback signal FB3 system detects the output voltage of power supply circuit 260 by a voltage detection circuit 275 and produces.When the output voltage of power supply circuit 260 causes the level of the 3rd feedback signal FB3 higher than level during the second reference voltage signal Vr2 higher than a predetermined protection value, overvoltage comparator 208 output over-voltage protection signal OVP makes protected location 235 export a guard signal Prot and controls driver element 230 stopping output control signal Sc.
Current source used in the present invention (the first current source I1 namely in above-described embodiment, the second current source I2 and the 3rd current source I3) can be fixed current source; Or can be the controlled current source adjusting size according to feedback signal FB, make control circuit have also good transient response.Such as: become large with linear formula, staged or other forms with level difference according to the level difference of feedback signal FB and reference voltage signal and improve the size of current of current source.Referring to Fig. 5, is the circuit diagram of controlled current flow circuit according to a preferred embodiment of the present invention.Controlled current flow circuit comprises current source Io, Ia, Ib, Ic, current switch Ma, Mb, Mc and comparator Coa, Cob, Coc.Comparator Coa compares the absolute level difference FB-Vr(and comparison reference signal Vra of a comparison reference signal Vra and feedback signal and reference voltage signal and the absolute value of feedback signal and reference voltage signal level difference).When absolute level difference FB-Vr is greater than comparison reference signal Vra, comparator Coa exports control signal Sa with On current switch Ma, so that the electric current of current sources la is added electric current I s.Comparator Cob compares a comparison reference signal Vrb and absolute level difference FB-Vr.When absolute level difference FB-Vr is greater than comparison reference signal Vrb, comparator Cob exports control signal Sb with On current switch Mb, so that the electric current of current source Ib is added electric current I s.Comparator Coc compares a comparison reference signal Vrc and absolute level difference FB-Vr.When absolute level difference FB-Vr is greater than comparison reference signal Vrc, comparator Coc exports control signal Sc with On current switch Mc, so that the electric current of current source Ic is added electric current I s.Above-mentioned comparison reference signal Vrb is greater than comparison reference signal Vra, and comparison reference signal Vrc is greater than comparison reference signal Vrb.Therefore, when absolute level difference FB-Vr is less than comparison reference signal Vra, electric current I s equals the electric current of current source Io.When absolute level difference FB-Vr is less than comparison reference signal Vrb but is greater than comparison reference signal Vra, electric current I s equals the electric current summation of current source Io and current sources la.The rest may be inferred, and controlled current flow circuit can be larger along with the level difference of feedback signal and reference signal, provides the transient response capability improving that larger electric current makes control circuit.
The present invention discloses with preferred embodiment hereinbefore, and the those of ordinary skill in right any art it should be understood that this embodiment only for describing the present invention, and should not be read as and limit the scope of the invention.It should be noted, all changes with this embodiment equivalence and displacement, all should be set to and be covered by category of the present invention.Therefore, protection scope of the present invention is when being as the criterion with the claim person of defining above.
Claims (15)
1. a drive circuit, comprises:
One power supply circuit, couples an input power, to convert the electric power of this input power to a driving electric power to drive a load according to a control signal;
One transistor unit, this transistor unit has at least one load coupled end in order to couple this load, to adjust the size of current flowing through this load; And
One feedback control circuit, the feedback signal according to the state representing this load produces this control signal, and this feedback control circuit comprises:
One electric capacity;
One charhing unit, has one first current source, in order to charge to this electric capacity;
One discharge cell, has one second current source and couples this electric capacity, and in order to discharge to this electric capacity, wherein the electric current of this first current source and this second current source improves greatly according to the level difference change of this feedback signal and a reference voltage signal;
One feedback control unit, according to this feedback signal to control this charhing unit to this capacitor charging;
One control circuit of duty ratio, in order to produce this control signal and the duty ratio of this control signal of Voltage Cortrol according to this electric capacity; And
One feedback control switch, couples this electric capacity, this charhing unit and this discharge cell, and switches between a conducting state and a closed condition according to a dim signal.
2. drive circuit according to claim 1, wherein this transistor unit has several transistor and several current control circuit, each this transistor has a control end, a current feedback terminal and this load coupled end, each current control circuit according to the state of this transistor corresponding to the control of Electric potentials of this current feedback terminal of this transistor of correspondence, with the size of current of control flow check through this transistor of correspondence.
3. drive circuit according to claim 2, wherein this several current control circuit also closes this several transistor according to a dim signal.
4. drive circuit according to claim 2, wherein this feedback control circuit is when this feedback control switch is in this conducting state, judge the current potential of those load coupled ends arbitrary whether lower than one first predetermined potential value or higher than one second predetermined potential value time, if then this feedback control circuit stops this power supply circuit to carry out electric power conversion to the electric power of this input power, wherein this second predetermined potential value is higher than this first predetermined potential value.
5. drive circuit according to claim 1, wherein the size of current of this charhing unit adjusts according to this feedback signal.
6. drive circuit according to claim 1, wherein the size of current of this discharge cell adjusts according to this feedback signal.
7. a drive circuit, comprises:
One power supply circuit, in order to provide a driving electric power to drive a load;
One transistor unit, this transistor unit has at least one load coupled end in order to couple this load, to adjust the size of current flowing through this load; And
One feedback control circuit, according to this driving electric power size that this power supply circuit of control of Electric potentials of this at least one load coupled end provides;
Wherein, this feedback control circuit comprises a feedback signal and produces circuit and a feedback control switch, this feedback signal produces circuit and couples this transistor unit by this feedback control switch, to produce a feedback processing signal according to the current potential of this at least one load coupled end, this feedback control switch is coupled to this feedback signal and produces circuit to switch between a conducting state and a closed condition according to a dim signal
Wherein, this feedback signal generation circuit comprises:
One electric capacity, in order to produce this feedback processing signal;
One charhing unit, has one first current source, in order to charge to this electric capacity; And
One discharge cell, has one second current source and couples this electric capacity, and in order to discharge to this electric capacity, wherein the electric current of this first current source and this second current source improves greatly according to the level difference change of this feedback signal and a reference voltage signal.
8. drive circuit according to claim 7, wherein this transistor unit has several transistor and several current control circuit, each this transistor has a control end, a current feedback terminal and this load coupled end, each this current control circuit according to the state of this transistor corresponding to the control of Electric potentials of this current feedback terminal of this transistor of correspondence, with the size of current of control flow check through this transistor of correspondence.
9. drive circuit according to claim 8, wherein this feedback control circuit also comprises a control circuit of duty ratio, the electric power of one input power is changed to provide this electric power according to this this power supply circuit of feedback processing signal controlling, this control circuit of duty ratio, when this feedback control switch is in this closed condition, stops this power supply circuit to carry out electric power conversion.
10. drive circuit according to claim 8, wherein this several current control circuit also closes this several transistor according to a dim signal.
11. drive circuits according to claim 8, wherein this feedback control circuit is when this feedback control switch is in this conducting state, judge the current potential of those load coupled ends arbitrary whether lower than one first predetermined potential value or higher than one second predetermined potential value time, if then this feedback control circuit stops this power supply circuit to carry out electric power conversion to the electric power of an input power, wherein this second predetermined potential value is higher than this first predetermined potential value.
12. 1 kinds of feedback control circuits, in order to control a power-switching circuit, to stablize the output of this power-switching circuit, this feedback control circuit comprises:
One electric capacity;
One charhing unit, has one first current source and couples this electric capacity, in order to charge to this electric capacity;
One discharge cell, has one second current source and couples this electric capacity, and in order to discharge to this electric capacity, wherein the electric current of this first current source and this second current source improves greatly according to the level difference change of this feedback signal and a reference voltage signal;
One feedback control unit, according to representing a feedback signal of this output state to control this charhing unit to this capacitor charging; And
One duty ratio adjustment unit, in order to produce a control signal, and the duty ratio of this control signal of Voltage Cortrol according to this electric capacity;
Wherein, this charhing unit and this discharge cell at least one of them adjusts exported size of current according to this feedback signal.
13. control circuits according to claim 12, wherein this charhing unit has one first switch and is coupled between this first current source and this electric capacity, this feedback control unit has a comparator, this comparator according to this feedback signal and this reference voltage signal to control this first switch conduction and closedown.
14. control circuits according to claim 12, wherein this charhing unit has one first switch and is coupled between this first current source and this electric capacity, this discharge cell has a second switch and one second current source, this second switch is coupled between this second current source and this electric capacity, and this feedback control unit controls conducting and the closedown of this first switch and this second switch according to this feedback signal.
15. control circuits according to claim 12, wherein this charhing unit has one the 3rd switch and one the 3rd current source, 3rd switch is coupled between the 3rd current source and this electric capacity, this discharge cell has a second switch, this second switch is coupled between this second current source and this electric capacity, this feedback control unit is according to this feedback signal to control conducting and the closedown of the 3rd switch and this second switch, and wherein the size of current of the 3rd current source is greater than the size of current of this first current source.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW100109787 | 2011-03-22 | ||
| TW100109787A TWI445440B (en) | 2011-03-22 | 2011-03-22 | Driving circuit |
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| CN102695325A CN102695325A (en) | 2012-09-26 |
| CN102695325B true CN102695325B (en) | 2015-02-04 |
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| CN201110161891.5A Expired - Fee Related CN102695325B (en) | 2011-03-22 | 2011-06-16 | Drive circuit and feedback control circuit |
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| US9197132B2 (en) | 2006-12-01 | 2015-11-24 | Flextronics International Usa, Inc. | Power converter with an adaptive controller and method of operating the same |
| US9246391B2 (en) | 2010-01-22 | 2016-01-26 | Power Systems Technologies Ltd. | Controller for providing a corrected signal to a sensed peak current through a circuit element of a power converter |
| US9190898B2 (en) | 2012-07-06 | 2015-11-17 | Power Systems Technologies, Ltd | Controller for a power converter and method of operating the same |
| US20140091720A1 (en) * | 2012-09-28 | 2014-04-03 | Power Systems Technologies, Ltd. | Controller for Use with a Power Converter and Method of Operating the Same |
| TWI583245B (en) * | 2012-10-05 | 2017-05-11 | 通嘉科技股份有限公司 | Led drivers and led driving methods therefor |
| TWI487253B (en) | 2013-02-20 | 2015-06-01 | Anpec Electronics Corp | Switching regulator controlling method and circuit |
| US9300206B2 (en) | 2013-11-15 | 2016-03-29 | Power Systems Technologies Ltd. | Method for estimating power of a power converter |
| CN105282907B (en) * | 2014-07-07 | 2017-08-25 | 盛群半导体股份有限公司 | LED backlight drive device |
| CN106817022A (en) * | 2015-11-30 | 2017-06-09 | 展讯通信（上海）有限公司 | Optimize the power supply changeover device of transient response characteristic |
| CN105790219A (en) * | 2016-03-21 | 2016-07-20 | 福州福大海矽微电子有限公司 | Flyback switching power supply outputting free-wheeling diode open circuit protection circuit and method |
| CN106714384A (en) * | 2017-01-22 | 2017-05-24 | 湖南电将军新能源有限公司 | Light-emitting diode (LED) drive circuit and LED drive method for automobile starting power supply |
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| TW201240514A (en) | 2012-10-01 |
| CN102695325A (en) | 2012-09-26 |
| TWI445440B (en) | 2014-07-11 |
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