CN103260301B - Drive circuit driving light-emitting diode light source and controller - Google Patents

Drive circuit driving light-emitting diode light source and controller Download PDF

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Publication number
CN103260301B
CN103260301B CN201310009628.3A CN201310009628A CN103260301B CN 103260301 B CN103260301 B CN 103260301B CN 201310009628 A CN201310009628 A CN 201310009628A CN 103260301 B CN103260301 B CN 103260301B
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China
Prior art keywords
signal
current
controller
flowing
electric current
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CN201310009628.3A
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CN103260301A (en
Inventor
阎铁生
林永霖
郭清泉
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O2Micro International Ltd
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O2Micro International Ltd
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Priority claimed from US13/535,561 external-priority patent/US20120268023A1/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/355—Power factor correction [PFC]; Reactive power compensation
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention provides a drive circuit driving a light-emitting diode light source and a controller. The driving circuit for driving the light-emitting diode (LED) light source includes a buck-boost converter and a controller. The buck-boost converter receives an input voltage and an input current and powers the LED light source, and comprises a switch controlled by a driving signal PWM1. The controller receives a first signal IAVG indicating a current through the LED light source, and generates the driving signal based on the first signal to control the switch and to adjust the current through the LED light source. The buck-boost converter further comprises a current sensor which provides a second signal ISEN indicating an instant current flowing through the buck-boost converter, wherein the first signal is derived from the second signal, and wherein a reference ground of the controller is different from a ground of the driving circuit. The drive circuit and the controller not only stabilize current flowing through loads at a target current value and improve current control precision, but also correct power factors of the drive circuit and improve power supply quality.

Description

Drive drive circuit and the controller of LED source
Technical field
The present invention relates to a kind of drive circuit, relate in particular to a kind of drive circuit and controller that drives LED source.
Background technology
Figure 1 shows that a kind of block diagram of traditional light source driving circuit 100.This drive circuit 100 for driving light source as light-emitting diode chain 108.It is drive circuit 100 power supplies that power supply 102 provides input voltage VIN.Drive circuit 100 comprises buck converter, this buck converter under the control of controller 104 for light-emitting diode chain 108 provides the VOUT of the voltage after conversion.This buck converter comprises diode 114, inductance 112, electric capacity 116 and switch 106.Resistance 110 is connected with switch 106.When switch 106 is connected, resistance 110 and inductance 112 and 108 couplings of light-emitting diode chain, the feedback signal of the electric current of the inductance 112 of flowing through is indicated in generation.When switch 106 disconnects, resistance 110 disconnects with inductance 112 and light-emitting diode chain 108, thereby there is no the electric current resistance 110 of flowing through.
Switch 106 is controlled by controller 104.When switch 106 is connected, electric current is flowed through light-emitting diode chain 108, inductance 112, switch 106, resistance 110 to ground.Under the effect of inductance 112, electric current increases gradually.When electric current increases to default lowest high-current value, controller 104 cut-off switch 106.When switch 106 disconnects, electric current flow through light-emitting diode chain 108, inductance 112 and diode 114.Controller 104 is turn on-switch 106 again over time.Therefore, controller 104 is according to described default lowest high-current value controlled hypotension converter.Yet, the fail to be convened for lack of a quorum impact of voltage VOUT at the inductance value, input voltage VIN and light-emitting diode chain 108 two ends that are subject to inductance 112 of the average electrical of inductance 112 and light-emitting diode chain 108 of flowing through, is therefore difficult to the average current of the inductance 112 of flowing through (average current of the light-emitting diode chain 108 of also flowing through) accurately to be controlled.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of drive circuit and controller, to improve the accuracy of the output current of this drive circuit, and makes this drive circuit have higher power factor.
For solving the problems of the technologies described above, the invention provides a kind of drive circuit, this drive circuit comprises and falls booster converter and controller.The described booster converter that falls receives input voltage and input current and provides electric energy for load.The described booster converter that falls comprises by the switch that drives signal controlling.Controller, falls booster converter described in being coupled in, and receives the first induced signal of the electric current of indicating the described load of flowing through, and produces described driving signal to control described switch according to described the first induced signal, the electric current of described load thereby adjusting is flowed through.The described booster converter that falls also comprises the current monitor that is coupled in described switch, wherein said current monitor provides indication to fall the second induced signal of the transient current of booster converter described in flowing through, wherein said the first induced signal obtains from described the second induced signal, and the reference ground of wherein said controller is different from the ground of described drive circuit.
The present invention also provides a kind of controller, for controlling, falls booster converter.The described booster converter that falls receives input voltage and input current, and provides electric energy for load.Described controller comprises: the first sensor port, and the first induced signal of the electric current of the described load of flowing through is indicated in reception; Monitoring port, receive the monitor signal that falls the situation of the energy-storage units in booster converter described in indicating, the electric current of wherein said energy-storage units is controlled by switch, if and wherein described monitor signal indicates the electric current of the described energy-storage units of flowing through to be reduced to predetermined current value, described controller is connected described switch; And driving port, according to described the first induced signal and described monitor signal provide drive signal to described switch to control the transient current that falls booster converter described in flowing through, thereby regulate the described electric current of the described load of flowing through, wherein said the first induced signal is that the second induced signal that falls the described transient current of booster converter described in flowing through from indication obtains.
Drive circuit provided by the invention and controller, not only by the current stabilization of the load of flowing through in target current value, improved Current Control precision, and proofreaied and correct the power factor of drive circuit, improved power supply quality.
Accompanying drawing explanation
Below, by the description in conjunction with its accompanying drawing to some embodiments of the present invention, can further understand object of the present invention, specific structural features and advantage.
Figure 1 shows that a kind of block diagram of conventional light source drive circuit;
Figure 2 shows that the block diagram of light source driving circuit according to an embodiment of the invention;
Figure 3 shows that the circuit diagram of light source driving circuit according to an embodiment of the invention;
Figure 4 shows that the structural representation of Fig. 3 middle controller;
Figure 5 shows that the oscillogram of Fig. 4 middle controller;
Figure 6 shows that the another kind of structural representation of Fig. 3 middle controller;
Figure 7 shows that the signal waveforms that Fig. 6 middle controller generates or receives;
Figure 8 shows that the circuit diagram of light source driving circuit in accordance with another embodiment of the present invention;
Fig. 9 A is depicted as the block diagram of light source driving circuit in accordance with another embodiment of the present invention;
Fig. 9 B is depicted as the signal waveforms that in Fig. 9 A, drive circuit generates or receives;
Figure 10 shows that the circuit diagram of the light source driving circuit of another embodiment according to the present invention;
Figure 11 shows that the structural representation of Fig. 9 A middle controller;
Figure 12 shows that the signal waveforms that light source driving circuit generates or receives according to an embodiment of the invention;
Figure 13 shows that the method flow diagram that drives according to an embodiment of the invention load;
Figure 14 shows that the circuit diagram of the light source driving circuit of another embodiment according to the present invention;
Figure 15 shows that the structural representation of Figure 14 middle controller according to an embodiment of the invention;
Figure 16 shows that according to the present invention again the circuit diagram of the light source driving circuit of another embodiment;
Figure 17 shows that according to the present invention again the circuit diagram of the light source driving circuit of another embodiment;
Figure 18 shows that the signal waveforms that light source driving circuit generates or receives in accordance with another embodiment of the present invention.
Embodiment
To embodiments of the invention be provided to detailed explanation below.Although the present invention is set forth and illustrated by these execution modes, it should be noted that the present invention is not merely confined to these execution modes.On the contrary, all substitutes, variant and the equivalent in the defined invention spirit of appended claim and invention scope contained in the present invention.
In addition, for better explanation the present invention, in embodiment below, provided numerous details.It will be understood by those skilled in the art that and there is no these details, the present invention can implement equally.In other example, the method for knowing for everybody, flow process, element and circuit are not described in detail, so that highlight purport of the present invention.
Figure 2 shows that the block diagram of light source driving circuit 200 according to an embodiment of the invention.Light source driving circuit 200 comprises rectifier 204.Rectifier 204 receives from the input voltage of power supply 202 and for power converter 206 voltage after adjustment is provided.Power converter 206 receives voltage after adjusting and provides output power for load 288.Power converter 206 can be buck converter or booster converter.In one embodiment, power converter 206 comprise energy-storage units 214 and for the current monitor 278(that monitors energy-storage units 214 situations such as a resistance).Current monitor 278 provides induced signal ISEN for controller 210.This induced signal ISEN indicates the transient current of the energy-storage units 214 of flowing through.Light source driving circuit 200 also comprises filter 212, for producing induced signal IAVG according to induced signal ISEN.Induced signal IAVG indicates the average current of the energy-storage units 214 of flowing through.Controller 210 receives induced signal ISEN and induced signal IAVG, and controls the average current of the energy-storage units 214 of flowing through, and this average current is equated with target current value.
Figure 3 shows that the circuit diagram of light source driving circuit 300 according to an embodiment of the invention.In Fig. 3, number identical parts with Fig. 2 and there is similar function.In the example of Fig. 3, light source driving circuit 300 comprises rectifier 204, power converter 206, filter 212 and controller 210.Rectifier 204 can be the bridge rectifier that comprises diode D1-D4.The voltage that rectifier 204 is adjusted from power supply 202.Power converter 206 receives the voltage after the adjustment of rectifiers 204 outputs and produces output power is load (as light-emitting diode chain 208) power supply.
In the example of Fig. 3, power converter 206 is buck converters.This buck converter comprises electric capacity 308, switch 316, diode 314, current monitor 278(such as resistance 218), the inductance 302 intercoupling and inductance 304 and electric capacity 324.Diode 314 is between switch 316 and the ground of light source driving circuit 300.Electric capacity 324 is in parallel with light-emitting diode chain 208.In one embodiment, inductance 302 and inductance 304 electromagnetic coupled each other.Inductance 302 and inductance 304 are all connected to a common node 333.In the example of Fig. 3, common node 333 is between resistance 218 and inductance 302.Yet the present invention is not limited to this structure, common node 333 also can be between switch 316 and resistance 218.Common node 333 for controller 210 provide with reference to ground.In one embodiment, the reference ground of controller 210 is different with the ground of light source driving circuit 300.By switching on and off switch 316, the electric current of the inductance 302 of flowing through can be adjusted, thereby regulates the electric power of light-emitting diode chain 208.The situation of inductance 304 monitoring inductance 302, such as, whether monitoring stream is reduced to default current value through the electric current of inductance 302.
One end of resistance 218 is connected with the node between switch 316 and diode 314 negative electrodes, and the other end is connected with inductance 302.Resistance 218 provides induced signal ISEN, and when switch 316 switches on and off, this induced signal ISEN all can indicate the transient current of the inductance 302 of flowing through.In other words, no matter switch 316 is connected while still disconnecting, the equal energy monitoring stream of resistance 218 is through the transient current of inductance 302.The average current that filter 212 is coupled with resistance 218 and provides induced signal IAVG, this induced signal IAVG indication to flow through inductance 302.In one embodiment, filter 212 comprises resistance 320 and electric capacity 322.
Controller 210 receives induced signal ISEN and induced signal IAVG, and equals target current value by being switched on or switched off switch 316 make the to flow through average current of inductance 302.The electric capacity 324 filterings ripple of electric current of light-emitting diode chain 208 of flowing through, thus the electric current of the light-emitting diode chain 208 that makes to flow through is relatively steadily and the average current of the inductance 302 that equals to flow through.Therefore the electric current of light-emitting diode chain 208 of making to flow through equates with target current value." equate " it is in the situation that do not consider the undesirable situation of circuit element and ignore the electric power that is sent to controller 210 from inductance 304 herein with target current value.
In the example of Fig. 3, the port of controller 210 comprises ZCD, GND, DRV, VDD, CS, COMP and FB.304 couplings of port ZCD and inductance, for receive indication inductance 302 situations (such as, whether the electric current of the inductance 302 of flowing through is reduced to default current value " 0 ") monitor signal AUX.Monitor signal AUX also can indication light diode chain 208 whether in open-circuit condition.Port DRV and switch 316 are coupled and produce and drive signal (as pulse width modulating signal PWM1) to be switched on or switched off switch 316.Port VDD and inductance 304 are coupled and receive the electric power of self-inductance 304.Port CS and resistance 218 are coupled and receive the flow through induced signal ISEN of transient current of inductance 302 of indication.Port COMP is coupled by electric capacity 318 and the reference ground of controller 210.Port FB be coupled by filter 212 and resistance 218 and receives the induced signal IAVG of the average current of indicating the inductance 302 of flowing through.In the example of Fig. 3, port GND(is also the reference ground of controller 210) be connected to the common node 333 between resistance 218, inductance 302, inductance 304.
Switch 316 can be N-type mos field effect transistor (N-type MOSFET).The conducting state of switch 316 is determined by the voltage difference between the grid voltage of switch 316 and the voltage of port GND (being the voltage of common node 333).Therefore, the pulse width modulating signal PWM1 of port DRV output has determined the state of switch 316.When switch 316, connect, the reference ground of controller 210, higher than the ground of light source driving circuit 300, makes circuit of the present invention go for having the power supply of high voltage.
When switch 316 is connected, electric current switch 316, resistance 218, inductance 302, light-emitting diode chain 208 ground to light source driving circuit 300 of flowing through.When switch 316 disconnects, electric current flow through resistance 218, inductance 302, light-emitting diode chain 208 and diode 314.Inductance 304 and inductance 302 couplings and can monitor the situation of inductance 302, such as, whether monitoring stream is reduced to predetermined current value through the electric current of inductance 302.Controller 210 is the electric current through inductance 302 according to signal AUX, ISEN and IAVG monitoring stream, and by pulse width modulating signal PWM1 control switch 316, and the average current of the inductance 302 that makes to flow through equals target current value.So after electric capacity 324 filtering, the electric current of the light-emitting diode chain 208 of flowing through also equals target current value.
In one embodiment, controller 210 judges that according to monitor signal AUX whether light-emitting diode chain 208 is in open-circuit condition.If light-emitting diode chain 208 open circuits, the voltage on electric capacity 324 increases.When switch 316 is during in off-state, the voltage at inductance 302 two ends increases, and the voltage of monitor signal AUX also increases thereupon.Consequently, the electric current by port ZCD ramp metering device 210 increases.Therefore, controller 210 by switch 316 during in off-state the electric current of monitor signal AUX and ramp metering device 210 whether surpass a threshold value and judge that whether light-emitting diode chain 208 is in open-circuit condition.
Controller 210 judges that according to the voltage of port VDD whether light-emitting diode chain 208 is in short-circuit condition.If 208 short circuits of light-emitting diode chain, when switch 316 is during in off-state because inductance 302 two ends all with the ground coupling of light source driving circuit 300, so the voltage at inductance 302 two ends reduces.The voltage at inductance 304 two ends and the voltage of port VDD reduce thereupon.If when the voltage of switch 316 port VDD during in off-state is less than a voltage threshold, controller 210 judgement light-emitting diode chains 208 are in short-circuit condition.
Figure 4 shows that the structural representation of Fig. 3 middle controller 210.Figure 5 shows that the oscillogram of Fig. 4 middle controller 210.Fig. 4 is described in connection with Fig. 3 and Fig. 5.
In the example of Fig. 4, controller 210 comprises error amplifier 402, comparator 404 and pulse width modulating signal generator 408.Error amplifier 402 produces error signal VEA according to the voltage difference between reference signal SET and induced signal IAVG.Reference signal SET indicating target current value.Induced signal IAVG receives by port FB, indicates the average current of the inductance 302 of flowing through.Effect by error signal VEA make the to flow through average current of inductance 302 equals target current value.Comparator 404 and error amplifier 402 couplings, compare error signal VEA and induced signal ISEN.Induced signal ISEN receives by port CS, indicates the transient current of the inductance 302 of flowing through.Monitor signal AUX receives by port ZCD, indicates the electric current of the inductance 302 of flowing through whether to be reduced to predetermined current value (such as being reduced to 0).Pulse width modulating signal generator 408 and comparator 404 and port ZCD coupling, produce pulse width modulating signal PWM1 according to the output of comparator 404 and monitor signal AUX.Pulse width modulating signal PWM1 is by the conducting state of port DRV control switch 316.
The pulse width modulating signal PWM1 that 408 generations of pulse width modulating signal generator have the first state (as logical one) is with turn on-switch 316.When switch 316 is connected, electric current switch 316, resistance 218, inductance 302, light-emitting diode chain 208 ground to light source driving circuit 300 of flowing through.The electric current of inductance 302 of flowing through increases gradually, and the voltage of signal ISEN is increased gradually.In one embodiment, when switch 316 is connected, the voltage of monitor signal AUX is negative value.In controller 210 inside, comparator 404 compares error signal VEA and induced signal ISEN.When the voltage of induced signal ISEN surpasses the voltage of error signal VEA, comparator 404 is output as logical zero, otherwise comparator 404 is output as logical one.In other words, comparator 404 is output as a series of pulse.Under the effect of the trailing edge of exporting at comparator 404, the pulse width modulating signal PWM1 that 408 generations of pulse width modulating signal generator have the second state (as logical zero) is with cut-off switch 316.When switch 316 disconnects, the voltage of monitor signal AUX become on the occasion of.When switch 316 disconnects, electric current flow through resistance 218, inductance 302, light-emitting diode chain 208 and diode 314.The electric current of inductance 302 of flowing through reduces gradually, so the voltage of induced signal ISEN reduces gradually.When the electric current of the inductance 302 of flowing through is reduced to predetermined current value (as being reduced to 0), the voltage of monitor signal AUX can produce a trailing edge.Under the effect of monitor signal AUX trailing edge, the pulse width modulating signal PWM1 that 408 generations of pulse width modulating signal generator have the first state (as logical one) is with turn on-switch 316.
In one embodiment, the duty ratio of pulse width modulating signal PWM1 is determined by error signal VEA.If the voltage of induced signal IAVG is less than the voltage of reference signal SET, the voltage that error amplifier 402 increases error signal VEA is to increase the duty ratio of pulse width modulating signal PWM1, thereby the average current of the inductance 302 that makes to flow through increases, until the voltage of induced signal IAVG increases to the voltage of reference signal SET.If the voltage of induced signal IAVG is greater than the voltage of reference signal SET, the voltage that error amplifier 402 reduces error signal VEA is to reduce the duty ratio of pulse width modulating signal PWM1, thereby the average current of the inductance 302 that makes to flow through reduces, until the voltage of induced signal IAVG is reduced to the voltage of reference signal SET.Like this, the flow through average current of inductance 302 can be adjusted to target current value and equates.
Controller 210 also comprises startup and the low pressure lock-in circuit 401 that is coupled in its port VDD, for optionally start one or more parts of controller 210 inside according to different electric energy situations.In one embodiment, if the voltage on port VDD, higher than the first predeterminated voltage, starts and low pressure lock-in circuit 401 will start all parts in controller 210.If the voltage on port VDD is lower than the second predeterminated voltage, startup and low pressure lock-in circuit 401 are by parts all in closing controller 210.In one embodiment, the first predeterminated voltage is higher than the second predeterminated voltage.Port VDD is used for providing electric energy to controller 210.Port GND is coupled in the reference ground of controller 210.
Figure 6 shows that the another kind of structural representation of Fig. 3 middle controller 210.Figure 7 shows that the oscillogram of Fig. 6 middle controller 210.Fig. 6 is described in connection with Fig. 3 and Fig. 7.
In the example of Fig. 6, controller 210 comprises error amplifier 602, comparator 604, sawtooth signal generator 606, reset signal generator 608 and pulse width modulating signal generator 610.Error amplifier 602 produces error signal VEA according to the voltage difference between reference signal SET and induced signal IAVG.Reference signal SET indicating target current value.Induced signal IAVG receives by port FB, indicates the average current of the inductance 302 of flowing through.Effect by error signal VEA make the to flow through average current of inductance 302 equals target current value.Sawtooth signal generator 606 produces sawtooth signal SAW.Comparator 604 and error amplifier 602 and 606 couplings of sawtooth signal generator, and error signal VEA and sawtooth signal SAW are compared.Reset signal generator 608 produces reset signal RESET.Reset signal RESET acts on sawtooth signal generator 606 and pulse width modulating signal generator 610.Can be so that switch 316 connections under the effect of reset signal RESET.Pulse width modulating signal generator 610 and comparator 604 and reset signal generator 608 couplings, and produce pulse width modulating signal PWM1 according to the output of comparator 604 and reset signal RESET.Pulse width modulating signal PWM1 is by the conducting state of port DRV control switch 316.
In one embodiment, reset signal RESET is the pulse signal with fixed frequency.In another embodiment, reset signal RESET makes the pulse signal that the time of switch 316 in off-state is constant.Such as, in Fig. 7, it is that time of logical zero is constant that reset signal RESET makes pulse width modulating signal PWM1.
Under the effect of the pulse of reset signal RESET, pulse width modulating signal generator 610 produce there is the first state (as logical one) pulse width modulating signal PWM1 with turn on-switch 316.When switch 316 is connected, electric current switch 316, resistance 218, inductance 302, light-emitting diode chain 208 ground to light source driving circuit 300 of flowing through.Under the effect of the pulse of reset signal RESET, the voltage of the sawtooth signal SAW that sawtooth signal generator 606 produces starts to increase from initial value INI.When the voltage of sawtooth signal SAW increases to the voltage of error signal VEA, the pulse width modulating signal PWM1 that 610 generations of pulse width modulating signal generator have the second state (as logical zero) is with cut-off switch 316, and the voltage of sawtooth signal SAW is reset to initial value INI.Until the next pulse of reset signal RESET is when arrive, the voltage of sawtooth signal SAW just starts again to increase from initial value INI.
In one embodiment, the duty ratio of pulse width modulating signal PWM1 is determined by error signal VEA.If the voltage of induced signal IAVG is less than the voltage of reference signal SET, the voltage that error amplifier 602 increases error signal VEA is to increase the duty ratio of pulse width modulating signal PWM1, thereby the average current of the inductance 302 that makes to flow through increases, until the voltage of induced signal IAVG increases to the voltage of reference signal SET.If the voltage of induced signal IAVG is greater than the voltage of reference signal SET, the voltage that error amplifier 602 reduces error signal VEA is to reduce the duty ratio of pulse width modulating signal PWM1, thereby the average current of the inductance 302 that makes to flow through reduces, until the voltage of induced signal IAVG is reduced to the voltage of reference signal SET.Like this, the flow through average current of inductance 302 can be adjusted to target current value and equates.
Figure 8 shows that the circuit diagram of light source driving circuit light source driving circuit 800 in accordance with another embodiment of the present invention.In Fig. 8, number identical parts with Fig. 2, Fig. 3 and there is similar function.
Voltage after the adjustment that the port VDD of controller 210 exports by switch 804 reception rectifiers 204.At switch 804 and controller 210, with reference to the Zener diode 802 between ground, keep the voltage substantially constant of port VDD.In the example of Fig. 8, the port ZCD of controller 210 and inductance 302 couplings, receive the monitor signal AUX that indicates inductance 302 situations.Monitor signal AUX can indicate the electric current of the inductance 302 of flowing through whether to be reduced to predetermined current value (such as whether being reduced to 0).Common node 333 for controller 210 provide with reference to ground.
In sum, the invention provides a kind of power converter of controlling with the circuit to load supplying.This circuit comprises the current monitor through the electric current of energy-storage units (such as inductance) for monitoring stream, and controller.This controller is for controlling the switch with described inductance coupling high, thereby the average current of the described light source that makes to flow through equals target current value.No matter this switch connection or disconnection, the equal energy of this current monitor monitoring stream is through the electric current of described inductance.In one embodiment, power converter is that load (such as light-emitting diode chain) provides direct current.In another embodiment, power converter provides the charging current of direct current for battery.Compare with the traditional circuit in Fig. 1, the electric current that circuit of the present invention offers load or battery can obtain controlling more accurately.And circuit of the present invention goes for having the voltage source of high voltage.
Fig. 9 A is depicted as the block diagram of light source driving circuit 900 in accordance with another embodiment of the present invention.In Fig. 9 A, number identical parts with Fig. 2, Fig. 3 and there is similar function.In one embodiment, light source driving circuit 900 comprises filter 920, rectifier 204, power converter 906, load 288, sawtooth signal generator 902 and the controller 910 being coupled with power supply 202.Power supply 202 produces AC-input voltage V aC(such as, V aCthere is sine wave signal) with exchange input current I aC.Exchange input current I aCflow into filter 920.Electric current I aC' from filter 920, flow out, and flow into rectifier 204.Rectifier 204 receives AC-input voltage V by filter 920 aC, and commutating voltage V is provided on power line 912 iNwith rectified current I iN.Power line 912 is coupled between rectifier 204 and power converter 906.Power converter 906 is by commutating voltage V iNconvert output voltage V to oUT, for load 288 provides electric energy.Controller 910 and power converter 906 couplings, for controlling power converter 906, to regulate the electric current I that flows through load 288 oUT, and the power factor of proofreading and correct drive circuit 900.
Controller 910 produces and drives signal 962.In one embodiment, power converter 906 comprises switch 316.Drive signal 962 control switchs 316, thereby regulate the electric current I of the load 288 of flowing through oUT.Power converter 906 also generates the electric current I of indicating the load 288 of flowing through oUTinduced signal IAVG.
In one embodiment, with the sawtooth signal generator 902 of controller 910 couplings, according to driving signal 962 to generate sawtooth signal 960.For example, driving signal 962 can be pulse width modulating signal.In one embodiment, when driving signal 962 to be logic high, sawtooth signal 960 increases; When driving signal 962 to be logic low, sawtooth signal 960 is reduced to predeterminated voltage value (such as being reduced to 0V).
Advantageously, controller 910 produces driving signal 962 according to sawtooth signal 960 and induced signal IAVG.Drive signal 962 control switchs 316, the electric current I of the load 288 that makes to flow through oUTremain on target current value, to improve the accuracy of Current Control.In addition, drive signal 962 control switchs 316, regulate rectified current I iNaverage current I iN_ aVGwith commutating voltage V iNessence homophase, to proofread and correct the power factor of drive circuit 900.In the application, essence homophase refers to two waveforms same-phase in theory, yet in actual applications, due to the existence of electric capacity in circuit, causes two waveforms to have trickle differing.The operation principle of drive circuit 900 will further describe in Fig. 9 B.
Fig. 9 B is depicted as the oscillogram of the signal in the drive circuit 900 in Fig. 9 A according to one embodiment of present invention, and Fig. 9 B describes in connection with Fig. 9 A.Fig. 9 B has described AC-input voltage V aC, commutating voltage V iN, rectified current I iN, rectified current average current I iN_ aVG, electric current I aCwith exchange input current I aCwaveform.
For convenience of description, AC-input voltage V aCfor (being not limited to) sinusoidal waveform.Rectifier 204 rectification AC-input voltage V aC.In the embodiment of Fig. 9 B, commutating voltage V iNthere is the sinusoidal waveform after rectification, that is, and AC-input voltage V aCforward waveform retain, its negative sense waveform converts corresponding forward waveform to.
In one embodiment, the driving signal 962 that controller 910 produces is controlled rectified current I iN.Rectified current I iNsince a preset value (as zero ampere), increase.As rectified current I iNreach and commutating voltage V iNafter a proportional value, rectified current I iNdrop to preset value.As shown in Figure 9 B, rectified current I iNaverage current I iN_ aVGwaveform and commutating voltage V iNwaveform essence homophase.
Rectified current I iNfrom rectifier 204, flow out and flow into power converter 906.Rectified current I iNit is the electric current I that flows into rectifier 204 aC' electric current after rectification.As shown in Figure 9 B, as AC-input voltage V aCfor on the occasion of time, electric current I aCforward waveform and rectified current I iNforward waveform similar; As input current voltage V aCduring for negative value, electric current I aCnegative sense waveform and rectified current I iNwaveform corresponding.
In one embodiment, by employing, be coupled in the filter 920 between power supply 202 and rectifier 204, exchange input current I aCwith electric current I aC' mean value equate or proportional.Therefore, as shown in Figure 9 B, exchange input current I aCwaveform and AC-input voltage V aCwaveform essence homophase.In theory, exchange input current I aCwith AC-input voltage V aChomophase.Yet, in actual applications, owing to having electric capacity in filter 920 and power converter 906, exchange input current I aCwith AC-input voltage V aCbetween may there is trickle differing.In addition, exchange input current I aCwith AC-input voltage V aCwaveform is also roughly similar.Therefore, the power factor of drive circuit 900 has obtained correction, thereby has improved the power supply quality of drive circuit 900.
Figure 10 shows that the circuit diagram of light source driving circuit 1000 according to still a further embodiment.In Figure 10, number identical parts with Fig. 2, Fig. 3 and Fig. 9 A and there is similar function.Figure 10 is described in connection with Fig. 4, Fig. 5 and Fig. 9 A.
In the example of Figure 10, drive circuit 1000 comprises filter 920, rectifier 204, power converter 906, load 288, sawtooth signal generator 902 and the controller 910 that is coupled in power supply 202.In one embodiment, load 288 comprises LED source (as light-emitting diode chain 208).The present invention is not limited thereto, and load 288 can comprise the light source of other types or the load of other types (as battery pack).Filter 920 can be the inductive-capacitive filter that (being not limited to) comprises a pair of inductance and a pair of electric capacity.In one embodiment, controller 910 comprises a plurality of ports, such as ZCD port, GND port, DRV port, vdd terminal mouth, FB port, COMP port and CS port.
In one embodiment, power converter 906 comprises the input capacitance 1008 that is coupled in power line 912.Input capacitance 1008 reduces commutating voltage V iNripple, with level and smooth commutating voltage V iNwaveform.In one embodiment, electric capacity 1008 has relatively little capacitance (for example, being less than 0.5 microfarad), to help to eliminate or reduce commutating voltage V iNthe distortion of waveform.In addition, in one embodiment, because electric capacity 1008 is less, the electric current of the electric capacity 1008 of flowing through can be ignored.Therefore, when switch 316 is connected, the electric current I of the switch 316 of flowing through 214with the rectified current I flowing out from rectifier 204 iNabout equally.
The class of operation of the power converter 206 in power converter 906 and Fig. 3 seemingly.In one embodiment, energy-storage units 214 comprises inductance 302 and inductance 304, and inductance 302 electromagnetic coupled are in inductance 304.Inductance 302 and switch 316 and 208 couplings of light-emitting diode chain.Therefore, according to the conducting state of switch 316, electric current I 214the inductance 302 of flowing through.More specifically, in one embodiment, controller 910 produces and drives signal 962(as pulse width modulating signal on DRV port), with control switch 316, be switched on or switched off.When switch 316 closures, electric current I 214from power line 912, flow out, flow through switch 316 and inductance 302, and constantly increase.Electric current I 214can be drawn by formula (1):
△I 214=(V IN–V OUT)*T ON/L 302， (1)
Wherein, T oNthe time that represents switch 316 conductings, △ I 214represent electric current I 214variable quantity, L 302the inductance value that represents inductance 302.In one embodiment, controller 910 is controlled and is driven signal 962, makes T oNit is a steady state value.So, if output voltage V oUTsubstantially constant, at T oNin the time interval, electric current I 214variable quantity △ I 214with commutating voltage V iNproportional.In one embodiment, work as electric current I 214while being reduced to preset value (as zero ampere), switch 316 closures.Therefore, electric current I 214peak value and commutating voltage V iNproportional.
When switch 316 disconnects, electric current I 214from ground, flow out, and flow through diode 314 and inductance 302, flow to light-emitting diode chain 208.Accordingly, electric current I 214according to formula (2), reduce:
△I 214=(-V OUT)*T OFF/L 302。(2)
Wherein, T oFFthe turn-off time that represents switch 316.
In one embodiment, when switch 316 conducting, electric current I iNwith electric current I 214equate, when switching tube 316 disconnects, electric current I iNampere equals zero.
The situation of inductance 304 inductive sensors 302, for example, whether the electric current of the inductance 302 of flowing through drops to predetermined current value, for example zero ampere.Described in Fig. 5, in one embodiment, when switch 316 is closed, monitor signal AUX is low level, and when switch 316 disconnects, monitor signal AUX is high level.When the electric current I 214 of the inductance 302 of flowing through is reduced to predetermined current value, the voltage of monitor signal AUX produces a trailing edge.The ZCD port of controller 910 is coupled in inductance 304, is used for receiving monitor signal AUX.
In one embodiment, power converter 906 comprises output filter 1024.Output filter 1024 can be the electric capacity with relatively large capacitance (such as, be greater than 400 microfarads).So, the electric current I of the light-emitting diode chain 208 of flowing through oUTrepresent electric current I 214mean value.
Current monitor 218 produces the induced signal ISEN of the electric current of indicating the inductance 302 of flowing through.In one embodiment, the resistance-capacitance filter of filter 212 for comprising resistance 320 and electric capacity 322.The ripple that filter 212 is removed in current sensing signal ISEN, with the average current induced signal IAVG of generation current induced signal ISEN.So in the embodiment of Figure 10, average current induced signal IAVG indicates the electric current I of the light-emitting diode chain 208 of flowing through oUT.The port FB of controller 910 is used for receiving average current induced signal IAVG.
Sawtooth signal generator 902 is coupled in DRV port and CS port.Sawtooth signal generator 902 produces sawtooth signal 960 according to the driving signal 962 of DRV port on CS port.For example, sawtooth signal generator 902 comprises and is coupled between DRV port and CS port and resistance 1016 parallel with one another and diode 1018, also comprises and is coupled between CS port and ground and resistance 1012 parallel with one another and electric capacity 1014.During work, sawtooth signal 960 is according to driving signal 962 to change.More specifically, in one embodiment, driving signal 962 is pulse width modulating signal.When driving signal 962 to be logic high, electric current I 1 flows out from DRV port, through resistance 1016, flows into electric capacity 1014.Therefore, electric capacity 1014 is recharged, the voltage V of sawtooth signal 960 960increase.When driving signal 962 to be logic low, electric current I 2 flows out from electric capacity 1014, through diode 1018, and flows into DRV port.Therefore, electric capacity 1014 electric discharges, voltage V 960be reduced to zero volt spy.Sawtooth signal generator 902 can also comprise other assemblies, is not limited to the embodiment shown in Figure 10.
In one embodiment, controller 910 is integrated in an integrated circuit (IC) chip.The peripheral circuit assembly that resistance 1016 and 1012, diode 1018 and electric capacity 1014 are this integrated circuit (IC) chip.In another embodiment, sawtooth signal generator 902 and controller 910 also can be integrated in an integrated circuit (IC) chip.In this embodiment, CS port be can omit, thereby size and the cost of drive circuit 1000 reduced.Power converter 906 can also have other structures, is not limited to the embodiment shown in Figure 10.
Figure 11 shows that the structural representation of Fig. 9 A middle controller 910 according to an embodiment of the invention.In Figure 11, number identical parts with Fig. 4 and Fig. 9 A and there is similar function.Figure 11 is described in connection with Fig. 4, Fig. 5, Fig. 9 A and Figure 10.
In one embodiment, controller 910 has similar structure to the controller 210 in Fig. 4, and difference is, CS port reception sawtooth signal 960 rather than current sensing signal ISEN.Controller 910 produces and drives signal 962 according to sawtooth signal 960, average current induced signal IAVG and monitor signal AUX.Controller 910 comprises error amplifier 402, comparator 404 and pulse-width signal generator 408.Error amplifier 402, according to the difference between average current induced signal IAVG and the reference signal SET of expression target current value, produces error signal VEA.Comparator 404 is sawtooth signal 960 and error signal VEA relatively, to produce comparison signal S.Pulse width modulating signal generator 408 produces driving signal 962 according to comparison signal S and monitor signal AUX.
In one embodiment, as monitor signal AUX, indicate the electric current I of the inductance 302 of flowing through 214while dropping to preset value (as zero ampere), drive signal 962 to switch to the first level (as logic high), with Closing Switch 316.When sawtooth signal 960 reaches error signal VEA, drive signal 962 to switch to second electrical level (as logic low), with cut-off switch 316.Advantageously, because CS port receives sawtooth signal 960 rather than current sensing signal ISEN, the electric current I of the inductance 302 of flowing through 214peak value can not be limited to error signal VEA.Therefore, as described in formula (1), the electric current I of the inductance 302 of flowing through 214according to commutating voltage V iNchange.For example, electric current I 214peak value and commutating voltage V iNproportional rather than proportional with error signal VEA.
Controller 910 is controlled and is driven signal 962, so that electric current I oUTremain on the target current value being represented by reference signal SET.For example,, if electric current I oUTbe greater than target current value (as due to commutating voltage V iNvariation), error amplifier 402 reduces error signal VEA, to shorten the time T of switch 316 closures oN.So, electric current I 214average current reduce, to reduce electric current I oUT.Same, if electric current I oUTbe less than target current value, controller 910 extends the time T of switch 316 closures oN, to increase electric current I oUT.
Figure 12 shows that the signal waveforms that light source driving circuit (as drive circuit 900 or 1000) generates or receives according to an embodiment of the invention.Figure 12 is described in connection with Fig. 4, Fig. 9 A, Fig. 9 B and Figure 10.Figure 12 has described commutating voltage V iN, rectified current I iN, rectified current I iNaverage current I iN_ aVG, the light-emitting diode chain 208 of flowing through electric current I oUT, the flow through electric current I of inductance 302 of indication 214induced signal ISEN, error signal VEA, sawtooth signal 960 and drive signal 962.
As shown in figure 12, commutating voltage V iNit is the sine wave signal after rectification.At t1 constantly, drive signal 962 to become logic high.Therefore, switch 316 closures, the flow through electric current I of inductance 302 of indication 214induced signal ISEN increase.Meanwhile, sawtooth signal 960 is according to driving signal 962 to increase.
At t2 constantly, sawtooth signal 960 is increased to error signal VEA.Accordingly, controller 910 regulates and drives signal 962 is logic low, and sawtooth signal 960 drops to zero volt spy.Drive signal 962 cut-off switch 316, therefore, induced signal ISEN declines.In other words, sawtooth signal 960 and error signal VEA have determined to drive the time T of signal 962 logic highs oN.
At t3 constantly, electric current I 214be reduced to predetermined current value (as zero ampere), thus, controller 910 regulates and drives signal 962 is logic high, with Closing Switch 316.
In one embodiment, at commutating voltage V iNone-period in, the electric current I of the light-emitting diode chain 208 of flowing through oUTwith electric current I 214mean value equate or proportional.In conjunction with the description of Figure 11, controller 910 regulates electric current I oUTto the target current value being represented by reference signal SET.In addition, as shown in figure 12, represent electric current I 214induced signal ISEN during t1 to t4 with during t5 to t6, there is identical waveform.So, electric current I 214mean value during t1 to t4 equates with the mean value during t5 to t6.Therefore, electric current I oUTremain on target current value.In one embodiment, T oNby sawtooth signal 960 and error signal VEA, determined.Owing to driving in each cycle of signal 962, the time that sawtooth signal 960 rises to error signal VEA from zero volt spy all equates, so T oNconstant.According to formula (1), at T oNin time, electric current I 214variable quantity △ I 214with commutating voltage V iNproportional.So, as shown in figure 12, the peak value of induced signal ISEN and commutating voltage V iNproportional.
In one embodiment, when switch 316 is closed, electric current I iNwaveform and electric current I 214waveform similar, when switch 316 disconnects, electric current I iNampere equals zero.At t1 to t6 in the time period, rectified current I iNaverage current I iN_ aVGwith commutating voltage V iNessence homophase.Described in conjunction with Fig. 9 B, input current I aCwith input voltage V aCessence homophase, thereby the power factor of having proofreaied and correct drive circuit 900, and then improved power supply quality.
Figure 13 shows that according to an embodiment of the invention for driving the method flow diagram 1300 of the drive circuit (for example,, for driving the drive circuit 900 or 1000 of light-emitting diode chain 208) of load.Figure 13 is described in connection with Fig. 9 A to Figure 12.The concrete steps that Figure 13 is contained are only as example.That is to say, the present invention is also applicable to carry out other rational steps or Figure 13 is carried out to improved step.
In step 1302, receive input voltage (for example, commutating voltage V iN) and input current (for example, rectified current I iN).In step 1304, input voltage is converted into output voltage, for example, for load (, LED source) provides electric energy.In step 1306, for example, for example, according to driving signal (, driving signal 962) to control the electric current of energy-storage units (, energy-storage units 214) of flowing through, to regulate the electric current of the load of flowing through.
In step 1308, receive first induced signal (for example, average current induced signal IAVG) of the electric current of indicating the load of flowing through.In one embodiment, the first induced signal by indication flow through energy-storage units electric current the second induced signal filtering and obtain.In step 1310, according to driving signal to produce sawtooth signal.
In step 1312, by sawtooth signal and the first actuated signal control, drive signal, to regulate the electric current of the load of flowing through to target current value, and by average current and the input voltage essence homophase of control inputs electric current, to proofread and correct the power factor of drive circuit.In one embodiment, according to the difference of the first induced signal and reference signal, produce error signal, reference signal is indicated the target current value of the LED source of flowing through.Compare sawtooth signal and error signal, and receive the monitor signal of indication energy-storage units situation.When the current reduction of energy-storage units is to preset value if monitor signal indication is flowed through, switches and drive signal to the first state, and according to the comparison value of sawtooth signal and error signal, switch and drive signal to the second state.When driving signal in the first state, increase the electric current of the energy-storage units of flowing through, drive signal when the second state, the electric current of the energy-storage units that reduces to flow through.In one embodiment, if the electric current of the LED source of flowing through remains on target current value, the time that sawtooth signal is increased to error signal from preset value is constant.
Figure 14 shows that the circuit diagram of the light source driving circuit 1400 of another embodiment according to the present invention.In Figure 14, number identical parts with Fig. 2 and Fig. 3 and there is similar function.In the example of Figure 14, light source driving circuit 1400 comprises rectifier 204, power converter 1406, filter 212 and controller 1410.For example, rectifier 204 can be the bridge rectifier that comprises diode D1-D4.The alternating voltage that rectifier 204 receives from power supply 202.Power converter 1406 receives the commutating voltage of rectifier 204 outputs and produces output power is load (as light-emitting diode chain 208) power supply.
In the example of Figure 14, power converter 1406 is to fall booster converter (buck-boost converter), and it receives input voltage (for example, the commutating voltage of rectifier 204 outputs) and produces the output voltage that is greater than or less than input voltage.Booster converter falls in utilization, and light source driving circuit 1400 can be adjusted output voltage more neatly according to different loading demands.In addition, adopt the light source driving circuit 1400 that falls booster converter to there is relatively low total harmonic distortion and relative high power factor (PF).
In one embodiment, power converter 1406 comprises electric capacity 1408, switch 1416, resistance 1420, energy-storage units 1414, current monitor 1418(such as resistance 1418), diode 1412 and electric capacity 1424.Power converter 1406 receives input voltage and input currents, and provides electric energy for light-emitting diode chain 208.Switch 1416 is by driving signal controlling.Controller 1410 receives the induced signal IAVG of the electric current of indicating the light-emitting diode chain 208 of flowing through, and produces and drive signal to carry out control switch 1416 according to induced signal IAVG, to regulate the electric current of the light-emitting diode chain 208 of flowing through.
More specifically, in one embodiment, energy-storage units 1414 is coupled between switch 1416 and the ground of light source driving circuit 1400.Energy-storage units 1414 is coupled to the common node 1433 between switch 1416 and current monitor 1418.Common node 1433 for controller 1410 provide with reference to ground.In one embodiment, the reference ground of controller 1410 is different with the ground of light source driving circuit 1400.In the example of Figure 14, energy-storage units 1414 comprises inductance 1402 and inductance 1404.Inductance 1402 be coupled in controller 1410 reference and the ground of light source driving circuit 1400 between.The electric current of energy-storage units 1414 inductance 1402 of flowing through.Inductance 1404 and inductance 1402 electromagnetic coupled, for monitoring the situation of inductance 1402.More specifically, inductance 1402 and inductance 1404 are all connected to common node 1433.
Switch 1416 is controlled the electric current of energy-storage units 1414.The resistance 1420 being coupled between switch 1416 and energy-storage units 1414 provides induced signal VSEN to controller 1410, the state of induced signal VSEN indication energy-storage units 1414.For example, if the voltage of induced signal VSEN is greater than predeterminated voltage value (1.1V), controller 1410 cut-off switch 1416.
One end of current monitor 1418 is connected with node 1433, and the other end is connected with the negative electrode of diode 1412.Current monitor 1418 provides the induced signal ISEN of the transient current (for example indicating the transient current of the diode 1412 of flowing through when switch 1416 disconnects) of indicating the power converter 1406 of flowing through.When switch 1416 is connected, due to diode 1412 reverse bias, there is no the electric current diode 1412 of flowing through.Indicate the induced signal IAVG of the electric current of the light-emitting diode chain 208 of flowing through to obtain from induced signal ISEN.More specifically, the filter 212 being coupled between current monitor 1418 and controller 1410 produces the induced signal IAVG of the electric current of indicating the light-emitting diode chain 208 of flowing through according to induced signal ISEN.In one embodiment, filter 212 comprises resistance 320 and electric capacity 322.In the example of Figure 14, induced signal ISEN indicates the transient current of the power converter 1406 of flowing through, the transient current of the diode 1412 of for example flowing through.The average current of diode 1412 of flowing through equal the to flow through electric current of light-emitting diode chain 208.Yet in other embodiments, induced signal ISEN can indicate the transient current of other element of the power converter 1406 of flowing through, and is not limited to the embodiment shown in Figure 14.
Controller 1410 receives induced signal IAVG and equals target current value by being switched on or switched off switch 1416 make the to flow through average current of diode 1412.The electric capacity 1424 filterings ripple of electric current of light-emitting diode chain 208 of flowing through, thus the electric current of the light-emitting diode chain 208 that makes to flow through is relatively steadily and the average current of the diode 1412 that equals to flow through.Therefore, the flow through electric current of light-emitting diode chain 208 equates with target current value." equate from target current value " to refer to herein the light-emitting diode chain 208 of flowing through electric current can a little be different but within rational scope with target current value, thereby the current ripples being caused by undesirable circuit element can be left in the basket.
In the example of Figure 14, the port of controller 1410 comprises ZCD, GND, DRV, VDD, CS, COMP and FB.Port FB is by filter 212 and current monitor 1418 couplings, for receiving the induced signal IAVG of the average current of indicating the diode 1412 of flowing through.The average current of diode 1412 of flowing through equal the to flow through electric current of light-emitting diode chain 208.So, the port FB of controller 1410 receives the induced signal IAVG of the electric current of indicating the light-emitting diode chain 208 of flowing through.1404 couplings of port ZCD and inductance, for receive indication energy-storage units 1414 situation (such as, whether the electric current of the inductance 1402 of flowing through is reduced to the first predetermined current value, for example zero ampere) monitor signal AUX.The electric current of energy-storage units 1414 is controlled by switch 1416.If flowed through, the electric current of inductance 1402 is reduced to the first predetermined current value, for example zero ampere, and controller 1410 turn on-switchs 1416.Monitor signal AUX also can indication light diode chain 208 whether in open-circuit condition.Port DRV and switch 1416 couplings.Controller 1410 produces and drives signal (as pulse width modulating signal PWM1) at port DRV according to induced signal IAVG and monitor signal AUX.Pulse width modulating signal PWM1 controls the transient current of the power converter 1406 of flowing through, the transient current of the diode 1412 of for example flowing through, the electric current of light-emitting diode chain 208 thereby adjusting is flowed through.In one embodiment, pulse width modulating signal PWM1 has the first state (as logical one) and the second state (as logical zero).If pulse width modulating signal PWM1 is in the first state, switch 1416 is connected; And if pulse width modulating signal PWM1 is in the second state, switch 1416 disconnects.When driving signal in the first state, the electric current of the inductance 1402 of flowing through increases; And when driving signal in the second state, the electric current of the inductance 1402 of flowing through reduces.Port VDD and inductance 1404 couplings, for receiving the electric power of self-inductance 1404.Port CS and resistance 1420 couplings, for example, for receiving the induced signal VSEN of the state (whether the energy that energy-storage units 1414 is stored increases to default energy value) of indication energy-storage units 1414.Induced signal VSEN also can indication light diode chain 208 whether in short-circuit condition.Port COMP is coupled by electric capacity 318 and the reference ground of controller 1410.Port COMP provide error signal.In the example of Figure 14, port GND(is also the reference ground of controller 1410) be connected to the common node 1433 between current monitor 1418 and energy-storage units 1414.
Switch 1416 can be N-type mos field effect transistor (N-type MOSFET).The conducting state of switch 1416 is determined by the voltage difference between the grid voltage of switch 1416 and the voltage of port GND (being the voltage of common node 1433).Therefore, the pulse width modulating signal PWM1 of port DRV output has determined the state of switch 1416.When switch 1416, connect, the reference ground of controller 1410, higher than the ground of light source driving circuit 1400, makes circuit of the present invention go for having the power supply of high voltage.
In operation, when switch 1416 is connected, electric current switch 1416, resistance 1420, inductance 1402 ground to light source driving circuit 1400 of flowing through.When switch 1416 disconnects, electric current flow through inductance 1402, light-emitting diode chain 208, diode 1412 and current monitor 1418.Current monitor 1418 provides the induced signal ISEN of the transient current of indicating the diode 1412 of flowing through.Indicate the induced signal IAVG of the electric current of the light-emitting diode chain 208 of flowing through to obtain from induced signal ISEN.Therefore, in one embodiment, controller 1410 produces pulse width modulating signal PWM1 according to induced signal IAVG, and with control switch 1416, the average current of the diode 1412 that makes to flow through equals target current value.After electric capacity 1424 filtering, the electric current of the light-emitting diode chain 208 of flowing through also equals target current value.
In one embodiment, controller 1410 judges that according to monitor signal AUX whether light-emitting diode chain 208 is in open-circuit condition.If light-emitting diode chain 208 open circuit, the voltage on electric capacity 1424 increases, and when switch 1416 is during in off-state, the voltage at inductance 1402 two ends increases, and the voltage of monitor signal AUX also increases thereupon.Consequently, the electric current by port ZCD ramp metering device 1410 increases.Therefore, controller 1410 judges by monitor signal AUX whether the electric current of the inductance 1402 of flowing through during in off-state at switch 1416 surpasses the second predetermined current value (for example, 300 microamperes), thereby judges that whether light-emitting diode chain 208 is in open-circuit condition.
In one embodiment, controller 210 judges that according to induced signal VSEN whether light-emitting diode chain 208 is in short-circuit condition.If 208 short circuits of light-emitting diode chain, the energy of storing in energy-storage units 1414 increases, and the voltage of induced signal VSEN also increases thereupon.Consequently, the voltage of port CS increases thereupon.Therefore, controller 1410 judges by monitor signal VSEN whether the voltage of monitor signal VSEN surpasses predeterminated voltage value and (for example, 1.1V), thereby judge that whether light-emitting diode chain 208 is in short-circuit condition.
Figure 15 shows that the structural representation of Figure 14 middle controller 1410 according to an embodiment of the invention.In Figure 15, number identical parts with Fig. 4 and there is similar function.Figure 15 is described in connection with Figure 14.
In the example of Figure 15, controller 1410 comprises error amplifier 402, comparator 404 and pulse width modulating signal generator 408.Error amplifier 402 produces error signal VEA according to reference signal SET and induced signal IAVG at port COMP.Reference signal SET indicating target current value.Wherein, the voltage of error signal VEA is less than the predeterminated voltage value of judgement light-emitting diode chain 208 when short-circuit condition (for example, 1.1V).Induced signal IAVG receives by port FB, indicates the average current of the diode 1412 of flowing through.Effect by error signal VEA make the to flow through average current of diode 1412 equals target current value.Comparator 404 and error amplifier 402 couplings, for comparison error signal VEA and induced signal VSEN.Induced signal VSEN receives by port CS, the state of indication energy-storage units 1414.Monitor signal AUX receives by port ZCD, indicates the electric current of the inductance 1402 of flowing through whether to be reduced to the first predetermined current value (such as being reduced to zero ampere).Pulse width modulating signal generator 408 and comparator 404 and port ZCD coupling, produce pulse width modulating signal PWM1 according to the output of comparator 404 and monitor signal AUX.Pulse width modulating signal PWM1 is by the conducting state of port DRV control switch 1416.
In operation, when pulse width modulating signal PWM1 is in the first state (as logical one), switch 1416 is connected.When switch 1416 is connected, electric current switch 1416, resistance 1420, inductance 1402 ground to light source driving circuit 1400 of flowing through.The electric current of inductance 1402 of flowing through increases gradually, and the voltage of induced signal VSEN is increased gradually.In one embodiment, when switch 1416 is connected, the voltage of monitor signal AUX is negative value.In controller 1410 inside, comparator 404 compares error signal VEA and induced signal VSEN.When the voltage of induced signal VSEN surpasses the voltage of error signal VEA, comparator 404 is output as logical zero, otherwise comparator 404 is output as logical one.In other words, comparator 404 is output as a series of pulse.Under the effect of the trailing edge of exporting at comparator 404, the pulse width modulating signal PWM1 that 408 generations of pulse width modulating signal generator have the second state (as logical zero) is with cut-off switch 1416.In one embodiment, when switch 1416 disconnects, the voltage of monitor signal AUX be on the occasion of.When switch 1416 disconnects, electric current flow through inductance 1402, light-emitting diode chain 208, diode 1412 and current monitor 1418.The electric current of inductance 1402 of flowing through reduces gradually, so the voltage of induced signal VSEN reduces gradually.If monitor signal AUX indication is flowed through, the electric current of inductance 1402 is reduced to the first predetermined current value (as being reduced to zero ampere), and pulse width modulating signal PWM1 switches to the first state (as logical one).In one embodiment, when the electric current of the inductance 1402 of flowing through is reduced to the first predetermined current value (as being reduced to zero ampere), the voltage of monitor signal AUX can produce a trailing edge.Under the effect of monitor signal AUX trailing edge, the pulse width modulating signal PWM1 that 408 generations of pulse width modulating signal generator have the first state (as logical one) is with turn on-switch 1416.
In one embodiment, for example, if monitor signal AUX indicates the electric current of the inductance 1402 of flowing through to increase to the second predetermined current value (, 300 microamperes) when switch 1416 disconnects, pulse width modulating signal PWM1 remains on the second state (as logical zero).Controller 1410 judgement light-emitting diode chains 208 are in open-circuit condition.In one embodiment, if the voltage of monitor signal VSEN surpasses predeterminated voltage value, (for example, 1.1V), controller 1410 judgement light-emitting diode chains 208 are in short-circuit condition.When controller 1410 judgement light-emitting diode chains 208 are during in open-circuit condition or short-circuit condition, pulse width modulating signal PWM1 remain on the second state (as logical zero) with cut-off switch 1416 until abnormality no longer exist.
In one embodiment, the duty ratio of pulse width modulating signal PWM1 is determined by error signal VEA.If the voltage of induced signal IAVG is less than the voltage of reference signal SET, the voltage that error amplifier 402 increases error signal VEA is to increase the duty ratio of pulse width modulating signal PWM1, thereby the average current of the diode 1412 that makes to flow through increases, until the voltage of induced signal IAVG increases to the voltage of reference signal SET.If the voltage of induced signal IAVG is greater than the voltage of reference signal SET, the voltage that error amplifier 402 reduces error signal VEA is to reduce the duty ratio of pulse width modulating signal PWM1, thereby the average current of the diode 1412 that makes to flow through reduces, until the voltage of induced signal IAVG is reduced to the voltage of reference signal SET.Like this, the flow through average current of diode 1412 can be adjusted to target current value and equates.
Figure 16 shows that according to the present invention again the circuit diagram of the light source driving circuit 1600 of another embodiment.In Figure 16, number identical parts with Figure 14 and there is similar function.Except the structure of power converter 1406, in Figure 16, in the circuit diagram of light source driving circuit 1600 and Figure 14, the circuit diagram of light source driving circuit 1400 is similar.In the example of Figure 16, energy-storage units 1414 comprises inductance 1402.In one embodiment, power converter 1406 also can comprise the Zener diode D5 being coupled between inductance 1402 and controller 1410.Zener diode D5 forms bias level shifter to apply level shift (bias voltage) to the supply voltage of controller 1410, thereby from inductance 1402, provides suitable power supply to controller 1410 via port VDD.
Figure 17 shows that according to the present invention again the circuit diagram of the light source driving circuit 1700 of another embodiment.In Figure 17, number identical parts with Fig. 9 A, Figure 10 and Figure 14 and there is similar function.Except the structure of power converter 1406, in Figure 17, in the circuit diagram of light source driving circuit 1700 and Figure 10, the circuit diagram of light source driving circuit 1000 is similar.
In one embodiment, power converter 1406 comprises the input capacitance 1408 that is coupled in power line 912.Input capacitance 1408 reduces commutating voltage V iNripple, with level and smooth commutating voltage V iNwaveform.In one embodiment, input capacitance 1408 has relatively little capacitance to help to eliminate or reduce commutating voltage V iNthe distortion of waveform.In addition, in one embodiment, because input capacitance 1408 is less, the electric current of the input capacitance of flowing through 1408 can be ignored.Therefore, when switch 1416 is connected, the electric current I of the switch 1416 of flowing through 1402with the rectified current I flowing out from rectifier 204 iNabout equally.
Power converter 1406 in Figure 17 and the class of operation of the power converter 1406 in Figure 14 are seemingly.In one embodiment, according to the conducting state of switch 1416, electric current I 1412flow through diode 1412 and electric current I 1402the inductance 1402 of flowing through.More specifically, controller 910 produces and drives signal 962(as pulse width modulating signal on DRV port), with control switch 1416, be switched on or switched off.When switch 1416 is connected, electric current I 1402from power line 912, flow out, the switch 1416 of flowing through, resistance 1420, inductance 1402 arrive the ground of light source driving circuit 1700.Due to diode 1412 reverse bias, there is no the electric current diode 1412 of flowing through.During switch 1416 is connected, electric current I 1402can increase gradually according to formula (3):
△I 1402=V IN*T ON/L 1402， (3)
Wherein, T oNrepresent the time that switch 1416 is connected, △ I 1402represent electric current I 1402variable quantity, L 1402the inductance value that represents inductance 1402, and the voltage drop of the voltage drop of switch 1416 and resistance 1420 can be left in the basket.In one embodiment, controller 910 is controlled and is driven signals 962, makes T turn-on time in each switching cycle (driving the cycle of signal) of switch 1416 oNit is a steady state value.So, electric current I 1402variable quantity △ I 1402with commutating voltage V iNproportional.In one embodiment, work as electric current I 1402while being reduced to the first preset value (as zero ampere), switch 1416 is connected.Therefore, electric current I 1402peak value and commutating voltage V iNproportional.
At each switching cycle, switch 1416 is being connected T oNafter time period, be disconnected.When switch 1416 disconnects, electric current I 1412flow through inductance 1402, light-emitting diode chain 208, diode 1412 and current monitor 1418.Accordingly, electric current I 1412according to formula (4), reduce:
△I 1412=△I 1402=V OUT*T OFF/L 1402。(4)
Wherein, T oFFrepresent the time that switch 1416 disconnects, △ I 1412represent electric current I 1412variable quantity, and the voltage drop of the voltage drop of diode 1412 and current monitor 1418 can be left in the basket.In one embodiment, when switch 1416 is connected, rectified current I iNwith electric current I 1402equate, when switch 1416 disconnects, rectified current I iNampere equals zero.
In one embodiment, power converter 1406 comprises electric capacity 1424.Electric capacity 1424 can be the electric capacity with relatively large capacitance.So, the electric current I of the light-emitting diode chain 208 of flowing through oUTequal electric current I 1412mean value.
Controller 910 in Figure 17 and the class of operation of the controller 910 in Figure 10 are seemingly.In Figure 17, controller 910 comprises port ZCD, GND, DRV, VDD, CS, COMP and FB.1404 couplings of port ZCD and inductance, for receive indication inductance 1402 situation (such as, whether the electric current of the inductance 1402 of flowing through is reduced to the first predetermined current value, for example zero ampere) monitor signal AUX.Monitor signal AUX also can indication light diode chain 208 whether in open-circuit condition.Port GND is coupled in the common node 1433 between resistance 1418 and energy-storage units 1414.Port DRV and switch 1416 are coupled and produce and drive signal 962(as pulse width modulating signal PWM1) to be switched on or switched off switch 1416.Port VDD and inductance 1404 are coupled and receive the electric power of self-inductance 1404.Port COMP is coupled by electric capacity 318 and the reference ground of controller 910.Port FB is coupled by filter 212 and current monitor 1418 and receives the electric current I of indicating the light-emitting diode chain 208 of flowing through oUTinduced signal IAVG.
Be coupled in the sawtooth signal generator 902 of controller 910 for producing sawtooth signal 960 according to the driving signal 962 of DRV port on CS port.For example, sawtooth signal generator 902 comprises and is coupled between DRV port and CS port and resistance 1016 parallel with one another and diode 1018, also comprises and is coupled between CS port and the reference ground of controller 910 and resistance 1012 and electric capacity 1014 parallel with one another.Sawtooth signal 960 is according to driving signal 962 to change.More specifically, in one embodiment, driving signal 962 is pulse width modulating signal.When driving signal 962 to be logic high, electric current I 1 flows out from DRV port, through resistance 1016, flows into electric capacity 1014.Therefore, electric capacity 1014 is recharged, the voltage V of sawtooth signal 960 960increase.When driving signal 962 to be logic low, electric current I 2 flows out from electric capacity 1014, through diode 1018, and flows into DRV port.Therefore, electric capacity 1014 electric discharges, voltage V 960be reduced to zero volt spy.Sawtooth signal generator 902 can also comprise other assemblies, is not limited to the embodiment shown in Figure 17.
Advantageously, controller 910 produces driving signal 962 according to sawtooth signal 960 and induced signal IAVG.Controller 910 regulates the electric current I of the light-emitting diode chain 208 of flowing through oUTto target current value and by controlling rectified current I iNaverage current I iN_ aVGwith commutating voltage V iNessence homophase, to proofread and correct the power factor of drive circuit 1700.
Figure 18 shows that the signal waveforms that light source driving circuit (as drive circuit 1700) generates or receives in accordance with another embodiment of the present invention.Figure 18 is described in connection with Fig. 4, Fig. 9 A, Fig. 9 B and Figure 17.Figure 18 has described commutating voltage V iN, rectified current I iN, rectified current I iNaverage current I iN_ aVG, the inductance 1402 of flowing through electric current I 1402, the light-emitting diode chain 208 of flowing through electric current I oUT, the flow through electric current I of diode 1412 of indication 1412induced signal ISEN, error signal VEA, sawtooth signal 960 and drive signal 962.There is the light source driving circuit 1700 that falls booster converter and there is relatively low total harmonic distortion and relative high power factor (PF).
As shown in figure 18, commutating voltage V iNit is the sine wave signal after rectification.At t1 constantly, drive signal 962 to become the first state (as logic high).Therefore, switch 1416 is connected, the electric current I of the inductance 1402 of flowing through 1402increase.Due to diode 1412 reverse bias, there is no the electric current diode 1412 of flowing through.Meanwhile, sawtooth signal 960 increases during the first state (as logic high) that drives signal 962.
At t2 constantly, when sawtooth signal 960 is increased to error signal VEA, drive signal 962 to switch to the second state (as logic low).Driving under the effect of signal 962 trailing edges, sawtooth signal 960 drops to zero volt spy and induced signal ISEN increases to electric current I 1402peak value.Drive signal 962 cut-off switch 1416, electric current start to flow through inductance 1402 and diode 1412 so electric current I 1402decline with induced signal ISEN.In other words, sawtooth signal 960 and error signal VEA have determined the time T of turn on-switch 1416 when driving signal 962 for logic high oN.
At t3 constantly, electric current I 1402and electric current I 1412be reduced to the first predetermined current value (as zero ampere), thus, controller 910 switches to logic high by driving signal 962, with turn on-switch 1416.
In one embodiment, at commutating voltage V iNone-period in, the electric current I of the light-emitting diode chain 208 of flowing through oUTwith electric current I 1412mean value equate or proportional.In conjunction with the description of Figure 11, controller 910 is by electric current I oUTbe adjusted to the target current value being represented by reference signal SET.In addition, as shown in figure 18, represent electric current I 1412induced signal ISEN during t1 to t4 with during t5 to t6, there is identical waveform.So, electric current I 1412mean value during t1 to t4 equates with the mean value during t5 to t6.Therefore, electric current I oUTremain on target current value.In one embodiment, T oNby sawtooth signal 960 and error signal VEA, determined.In one embodiment, owing to driving in each cycle of signal 962, the time that sawtooth signal 960 rises to error signal VEA from zero volt spy all equates, so T oNconstant.According to formula (3), at T oNin time, electric current I 1402variable quantity △ I 1402with commutating voltage V iNproportional.So as shown in figure 18, the peak value of induced signal ISEN (is electric current I 1402peak value) with commutating voltage V iNproportional.
In one embodiment, when switch 1416 is connected, rectified current I iNwaveform and electric current I 1402waveform similar, and when switch 1416 disconnects, rectified current I iNampere equals zero.At t1 to t6 in the time period, rectified current I iNaverage current I iN_ aVGwith commutating voltage V iNessence homophase.Described in conjunction with Fig. 9 B, controller 910 has been proofreaied and correct the power factor (PF) of drive circuit 1700 so that exchange input current I aCwith AC-input voltage V aCessence homophase.
The invention provides the drive circuit that drives load.Load can be light source, and for example LED source 208.The present invention is not limited thereto, and load can comprise the light source of other types or the load of other types (as battery pack).Drive circuit comprises electric power converter and controller.Electric power converter converts input voltage to output voltage, thinks that load provides electric energy.Power converter provides the induced signal of the electric current of indicating the load of flowing through.Drive circuit also comprises sawtooth signal generator, for producing sawtooth signal according to driving signal.Advantageously, controller produces driving signal according to induced signal and sawtooth signal.The electric current that driving signal controlling is flowed through energy-storage units, to regulate the electric current of the load of flowing through to target current value, and passes through average current and the input voltage essence homophase of control inputs electric current, to proofread and correct the power factor of drive circuit.
Above embodiment and accompanying drawing are only conventional embodiment of the present invention.Obviously, under the prerequisite that does not depart from the present invention's spirit that claims define and invention scope, can have and variously augment, revise and replace.It should be appreciated by those skilled in the art that the present invention can change to some extent in form, structure, layout, ratio, material, element, assembly and other side according to concrete environment and job requirement in actual applications under the prerequisite that does not deviate from invention criterion.Therefore, embodiment disclosed here is only illustrative rather than definitive thereof, and scope of the present invention is defined by claims and legal equivalents thereof, and is not limited to description before this.

Claims (15)

1. a drive circuit, is characterized in that, described drive circuit comprises:
Booster converter falls, receive input voltage and input current and provide electric energy for load, the described booster converter that falls comprises by the switch that drives signal controlling, be coupled in the current monitor of described switch, and be coupled in the energy-storage units between described switch and the ground of described drive circuit, wherein, the electric current of described energy-storage units is controlled by described switch, described energy-storage units is coupled to the common node between described switch and described current monitor, described common node provides the reference ground of described controller, and described different with reference to ground and described drive circuit of described controller described,
Controller, described in being coupled in, fall booster converter, described controller receives the first induced signal of the electric current of indicating the described load of flowing through, and produces described driving signal to control described switch according to described the first induced signal, thereby regulate the described electric current of the described load of flowing through
Filter, be coupled between described current monitor and described controller, described filter produces described the first induced signal according to the second induced signal being provided by described current monitor, the transient current of booster converter falls described in flowing through in indication, wherein, the described transient current that falls booster converter described in flowing through comprises described in flowing through and falls the transient current of the diode in booster converter, and the average current of the described diode of flowing through equal the to flow through described electric current of described load;
Sawtooth signal generator, is coupled in described controller, according to described driving signal, produces sawtooth signal,
Wherein, described controller comprises error amplifier, described error amplifier produces error signal according to the reference signal of described the first induced signal and indicating target current value, and described controller produces described driving signal according to described sawtooth signal and described error signal and regulates the described electric current of the described load of flowing through to described target current value, and by controlling the average current of described input current and described input voltage essence homophase to proofread and correct the power factor of described drive circuit, and
Wherein, described controller also receives the monitor signal of situation of the described energy-storage units of indication, and wherein, described driving signal has the first state and the second state, and when described driving signal is during in described the first state, the described electric current of the described energy-storage units of flowing through increases; When described driving signal is during in described the second state, the described current reduction of the described energy-storage units of flowing through; Wherein, if the indication of described monitor signal is flowed through, the described electric current of described energy-storage units is reduced to the first preset value, and described driving signal switches to described the first state; And wherein, if monitor signal indicates the described electric current of the described energy-storage units of flowing through to increase to the second preset value described in when described switch disconnects, described driving signal remains on described the second state.
2. drive circuit according to claim 1, it is characterized in that, the described booster converter that falls also comprises the resistance being coupled between described switch and described energy-storage units, described resistance provides voltage induced signal to described controller, the state of energy-storage units described in wherein said voltage induced signal designation, if and wherein the voltage of described voltage induced signal is greater than predeterminated voltage value, described controller disconnects described switch.
3. drive circuit according to claim 1, is characterized in that, described energy-storage units comprises:
The first inductance, be coupled in described controller described reference and the described ground of described drive circuit between, the electric current of wherein said energy-storage units described the first inductance of flowing through; And
The second inductance, with described the first inductance electromagnetic coupled, described the second inductance is monitored the situation of described the first inductance.
4. drive circuit according to claim 1, it is characterized in that, described energy-storage units comprise be coupled in described controller described reference and the described ground of described drive circuit between the first inductance, the electric current of wherein said energy-storage units described the first inductance of flowing through; And the wherein said booster converter that falls also comprises the Zener diode being coupled between described the first inductance and described controller.
5. drive circuit according to claim 1, it is characterized in that, described sawtooth signal increases during the first state of described driving signal, and wherein when described sawtooth signal is increased to described error signal, described driving signal switches to described the second state.
6. drive circuit according to claim 1, is characterized in that, if the described electric current of the described load of flowing through remains on described target current value, the time period that described sawtooth signal is increased to described error signal from the 3rd preset value is constant.
7. drive circuit according to claim 1, is characterized in that, described sawtooth signal generator comprises:
Be connected in diode and the first resistance between first node and Section Point in parallel; And
Be connected in the described with reference to the electric capacity between ground and the second resistance of described Section Point and described controller in parallel,
Wherein, described first node receives described driving signal, and described Section Point provides described sawtooth signal.
8. drive circuit according to claim 1, is characterized in that, described drive circuit also comprises:
Rectifier, receive AC-input voltage and exchange input current, and described input voltage and described input current are provided, wherein, described controller is proofreaied and correct the power factor (PF) of described drive circuit so that described interchange input current and described AC-input voltage essence homophase.
9. a controller, falls booster converter for controlling, described in fall booster converter and receive input voltage and input current, and for load provides electric energy, it is characterized in that, described controller comprises:
The first sensor port, the first induced signal of the electric current of the described load of flowing through is indicated in reception;
Monitoring port, receive the monitor signal that falls the situation of the energy-storage units in booster converter described in indicating, the electric current of wherein said energy-storage units is controlled by switch, if and the flow through described electric current of described energy-storage units of described monitor signal indication is reduced to predetermined current value, described controller is connected described switch; And
Drive port, according to described the first induced signal and described monitor signal, provide and drive signal to control described in flowing through, to fall the transient current of booster converter to described switch, thereby regulate the described electric current of the described load of flowing through,
Wherein, described the first induced signal is that the second induced signal that falls the described transient current of booster converter described in flowing through from indication obtains, and
Wherein, described controller also receives the sawtooth signal changing according to described driving signal, and wherein said controller produces described electric current that described driving signal regulates the described load of flowing through to target current value and controls average current and the described input voltage essence homophase of described input current according to described the first induced signal, described monitor signal and described sawtooth signal.
10. controller according to claim 9, is characterized in that, described controller also comprises:
Compensation port, for providing error signal;
Wherein said driving signal has the first state and the second state, and when described driving signal is during in the first state, the described electric current of the described energy-storage units of flowing through increases; When described driving signal is during in the second state, the described current reduction of the described energy-storage units of flowing through.
11. controllers according to claim 10, is characterized in that, described controller also comprises:
Error amplifier, produces described error signal according to the reference signal of described the first induced signal and indicating target current value at described compensation port; And
With the comparator of described error amplifier coupling, the 3rd signal and described error signal that comparison signal port provides, to produce output signal.
12. controllers according to claim 11, is characterized in that, described controller also comprises:
Pulse width modulating signal generator, is coupled in described comparator, according to the described output signal of described comparator and described monitor signal, produces described driving signal.
13. controllers according to claim 9, it is characterized in that, described driving signal has the first state and the second state, wherein said sawtooth signal increases during the first state of described driving signal, wherein when described sawtooth signal is increased to error signal, described driving signal switches to described the second state, and wherein said error signal is to produce according to the reference signal of described the first induced signal and indicating target current value.
14. controllers according to claim 13, is characterized in that, if the described electric current of the described load of flowing through remains on described target current value, the time period that described sawtooth signal is increased to described error signal from preset value is constant.
15. controllers according to claim 9, it is characterized in that, described controller also receives the voltage induced signal of state of the described energy-storage units of indication, and if wherein the voltage of described voltage induced signal be greater than predeterminated voltage value, described controller disconnects described switch.
CN201310009628.3A 2012-06-28 2013-01-10 Drive circuit driving light-emitting diode light source and controller Expired - Fee Related CN103260301B (en)

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