CN103796389B - High-high brightness hoisting module, controllable silicon light modulation LED drive circuit and system - Google Patents

Abstract

The invention provides a kind of controllable silicon light modulation LED drive circuit, the drain electrode of the second MOS transistor connects the source electrode of a power switch MOS transistor, and its source electrode connects a sampling resistor; The output of high-high brightness hoisting module is connected to peak current comparator first input end and feedforward resistance by the drain electrode electricity of the first MOS transistor of its inside, and the current signal that the first MOS transistor exports flows through feedforward resistance and produces direct current (DC) bias; Peak current comparator first input end is connected with sampling resistor electricity by feedforward resistance, its second input is connected with the output electricity of reference voltage source, its output is coupled to the grid of the second MOS transistor, peak current comparator is used for the voltage magnitude sum of feedforward resistance and sampling resistor to compare with the voltage threshold of reference voltage source, controls conducting and the closedown of the second MOS transistor.The present invention by high-high brightness hoisting module improve drive circuit connect controllable silicon dimmer time maximum current.

Description

High-high brightness hoisting module, controllable silicon light modulation LED drive circuit and system

Technical field

The present invention relates to field of LED drive, particularly relate to controllable silicon light modulation LED drive circuit and the system of the lifting of a kind of high-high brightness.

Background technology

See Fig. 1, the rough schematic view of the controllable silicon light modulation LED drive circuit of prior art.As shown in Figure 1, input AC AC power 101 is connected a controllable silicon dimmer 102, is connected to two inputs of rectifier bridge 103.Rectifier bridge 103 by after AC rectification through capacitor C1 filtering, produce the sinusoidal voltage after a rectification.Resistance R4 and capacitor C2 produces a low-voltage DC makes control chip 104 start.Transformer T1 has three windings, comprises a former limit winding T11, between the drain electrode being connected to capacitor C1 and power switch MOS transistor M1; A vice-side winding T12, is connected between sustained diode 1 and secondary output capacitor C4; An auxiliary winding T13, is connected to between electric diode D2 and circuit ground.When after circuit start, auxiliary winding T13 is that control chip 104 is powered; Auxiliary winding T13 also provides the information detecting sustained diode 1 current over-zero and detect output voltage overvoltage simultaneously.The controllable silicon light modulation LED drive circuit of prior art usually also comprises a bleeder resistance R1 and and to release switch M2; when anti exciting converter input current is less; control chip 104 opens the switch M2 that releases, for controllable silicon dimmer 102 provides enough maintenance electric currents.

There are following two shortcomings in above-mentioned traditional flyback LED drive circuit:

1) when used controllable silicon dimmer 102 maximum conduction angle degree is less, the output current of drive circuit declines more than output current when not using dimmer;

2) bleeder resistance R1 and switch M2 power consumption of releasing higher, loss LED drive circuit efficiency and temperature rise is higher, reduces system reliability.

Summary of the invention

The object of the invention is to, for controllable silicon light modulation LED drive circuit Problems existing in prior art, a kind of high-high brightness hoisting module, controllable silicon light modulation LED drive circuit and system are provided, by high-high brightness hoisting module, maximum current during drive circuit connection controllable silicon dimmer can be improved, eliminate leadage circuit simultaneously, use the input current of switch converters itself to provide the maintenance electric current of controllable silicon dimmer.

For achieving the above object, the invention provides a kind of high-high brightness hoisting module, comprising: an operational amplifier, one first MOS transistor and a reference voltage source; The first input end of described operational amplifier is the input of described high-high brightness hoisting module, in order to receive a sampled voltage signal, its second input is connected with the output electricity of described reference voltage source, its output electricity is connected to the grid of described first MOS transistor, described operational amplifier controls the conduction impedance of described first MOS transistor, ensures that two input terminal voltages are equal during described operational amplifier Closed loop operation; The source electrode electricity of described first MOS transistor is connected to the first input end of described operational amplifier, and its drain electrode is the output of described high-high brightness hoisting module, exports a current signal in order to control the output current of a LED drive circuit.

For achieving the above object, present invention also offers a kind of controllable silicon light modulation LED drive circuit, comprising: one second MOS transistor, a peak current comparator, feedforward resistance, a reference voltage source and a high-high brightness hoisting module of the present invention; The drain electrode electricity of described second MOS transistor is connected to the source electrode of a power switch MOS transistor, and the source electrode electricity of described second MOS transistor connects a sampling resistor; The output of described high-high brightness hoisting module is connected to described peak current comparator first input end and described feedforward resistance by the drain electrode electricity of described first MOS transistor, and the current signal that described first MOS transistor exports flows through feedforward resistance and produces direct current (DC) bias; Described peak current comparator first input end is connected with sampling resistor electricity by described feedforward resistance, its second input is connected with the output electricity of described reference voltage source, its output is coupled to the grid of described second MOS transistor, described peak current comparator is used for the voltage magnitude sum of described feedforward resistance and sampling resistor to compare with the voltage threshold of described reference voltage source, controls conducting and the closedown of described second MOS transistor.

For achieving the above object, present invention also offers a kind of controllable silicon light modulation LED drive system, comprise a controllable silicon dimmer, a rectifier bridge, a bus capacitor, a sampling resistor and controllable silicon light modulation LED drive circuit of the present invention; Described controllable silicon dimmer and one exchanges input source electricity and is connected, and controls the brightness of LED load by adjusting himself angle of flow; Described rectifier bridge is respectively with described controllable silicon dimmer and exchange input source electricity and be connected, and the sinusoidal signal rectification for exchanging input source is an amplitude is positive voltage signal; Described bus capacitor is coupled to two outputs of described rectifier bridge and is connected with the drain electrode electricity of a power switch MOS transistor, for providing high-frequency current path for described power switch MOS transistor; The input of described high-high brightness hoisting module is connected with the drain electrode electricity of described bus capacitor and described power switch MOS transistor respectively; The drain electrode of described second MOS transistor is connected with the source electrode electricity of described power switch MOS transistor, and the source electrode of described second MOS transistor is connected with described sampling resistor electricity; Described peak current comparator first input end is connected with described sampling resistor electricity by described feedforward resistance; Described sampling resistor is connected to LED load by a transformer or inductance electricity.

The invention has the advantages that: by high-high brightness hoisting module, improve maximum current during drive circuit connection controllable silicon dimmer; Eliminate leadage circuit simultaneously, use the input current of switch converters itself to provide the maintenance electric current of controllable silicon dimmer, improve LED drive circuit efficiency and system reliability.

Accompanying drawing explanation

Fig. 1, the rough schematic view of the controllable silicon light modulation LED drive circuit of prior art;

Fig. 2, the configuration diagram of controllable silicon light modulation LED drive circuit of the present invention;

Fig. 3, the schematic diagram of voltage-dropping type controllable silicon light modulation LED drive system of the present invention;

Fig. 4, the work typical waveform figure of voltage-dropping type controllable silicon light modulation LED drive system of the present invention;

Fig. 5, the Vdim voltage of controllable silicon light modulation LED drive system of the present invention and the graph of a relation of Vcs crest voltage;

Fig. 6, the schematic diagram of buck-boost type controllable silicon light modulation LED drive system of the present invention;

Fig. 7, the schematic diagram of flyback controllable silicon light modulation LED drive system of the present invention.

Embodiment

Elaborate below in conjunction with the execution mode of accompanying drawing to controllable silicon light modulation LED drive circuit provided by the invention and system.

With reference to figure 2, the configuration diagram of controllable silicon light modulation LED drive circuit of the present invention, described drive circuit comprises: one second MOS transistor M2, peak current comparator 209, feedforward resistance R6, a reference voltage source ref1 and a high-high brightness hoisting module 21.

Described high-high brightness hoisting module 21 comprises: operational amplifier 210, a 1 first MOS transistor M3, a reference voltage source ref2, a voltage division processing unit and a filter unit.

It is that positive voltage signal Vbus goes forward side by side row relax that described voltage division processing unit receives outside amplitude.As preferred embodiment, described voltage division processing unit to comprise on one divider resistance R2 and once divider resistance R3; It is positive voltage signal Vbus that described upper divider resistance R2 one end receives outside amplitude, and the other end is connected with described lower divider resistance R3 electricity, described lower divider resistance R3 other end ground connection (such as chip ground).Upper divider resistance R2 and lower divider resistance R3 by the process to voltage signal Vbus, can detect the cut angle information of outside controllable silicon dimmer.

Described filter unit respectively electricity is connected to the first input end of described voltage division processing unit and described operational amplifier 210, described filter unit is used for carrying out filtering to the voltage signal after described voltage division processing cell processing, obtains the first input end that d. c. voltage signal Vdim exports described operational amplifier 210 to.As preferred embodiment, described filter unit comprises an a filter resistance R4 and filter capacitor C3; Described filter resistance R4 one end is coupled between described upper divider resistance R2 and lower divider resistance R3, and the other end respectively electricity is connected to the first input end of described filter capacitor C3 and described operational amplifier 210, described filter capacitor C3 other end ground connection.

The first input end of described operational amplifier 210 receives d. c. voltage signal Vdim, its second input is connected with the output electricity of described reference voltage source ref2, its output electricity is connected to the grid G of described first MOS transistor M3, described operational amplifier 210 controls the conduction impedance of described first MOS transistor M3, ensure during described operational amplifier 210 Closed loop operation that two input terminal voltages are equal, thus have electric current to flow through the first MOS transistor M3.

Wherein, described voltage division processing unit and filter unit are selectable unit, the described first input end stating operational amplifier 210 can be directly the input of described high-high brightness hoisting module 21, in order to receive a sampled voltage signal, in order to compare with the voltage signal of described reference voltage source ref2, described sampled voltage signal can be d. c. voltage signal Vdim.

The source S electricity of described first MOS transistor is connected to the first input end of described operational amplifier 210, and its drain D is the output of described high-high brightness hoisting module 21, and output current signal controls the output current of LED drive circuit.The output of described high-high brightness hoisting module 21 is connected to described peak current comparator 209 first input end and described feedforward resistance R6 by the drain D electricity of described first MOS transistor M3, the drain D output current signal of described first MOS transistor M3 is injected into an input of peak current comparator 209, because the input impedance of peak current comparator 209 is very high, this electric current all flows through feedforward resistance R6 and on R6, produces a DC offset voltage.

As optional execution mode, described high-high brightness hoisting module 21 comprises an input resistance R5 further; Described input resistance R5 is serially connected between described filter resistance R4 and the first input end of described operational amplifier 210, and is connected with the source S electricity of described first MOS transistor M3, for obtaining dividing potential drop and exporting described first MOS transistor M3 to.Described input resistance R5 can omit, described input resistance R5 short circuit during omission.Operational amplifier 210 controls the conduction impedance of the first MOS transistor M3, and ensure during operational amplifier 210 Closed loop operation that two input terminal voltages are equal, thus input resistance R5 two ends can obtain a voltage, this voltage is Vdim-Vref2; Generation current on input resistance R5, its size is (Vdim-Vref2)/R5; This electric current flows through the first MOS transistor M3, and is injected into the input of peak current comparator 209, and because the input impedance of peak current comparator 209 is very high, this electric current all flows through feedforward resistance R6 and on R6, produces a DC offset voltage.

The drain D electricity of described second MOS transistor M2 is connected to the source S of a power switch MOS transistor M1, and the source S of M2 connects a sampling resistor R7.

Described peak current comparator 209 first input end is connected with sampling resistor R7 electricity by described feedforward resistance R6, and its second input is connected with the output electricity of described reference voltage source ref1, and its output is coupled to the grid G of the second MOS transistor M2.Described peak current comparator 209, for being compared by the voltage threshold of the voltage magnitude sum of described feedforward resistance R6 and sampling resistor R7 with described reference voltage source ref1, controls conducting and the closedown of described second MOS transistor M2; If the voltage magnitude sum of R6 and R7 reaches the voltage threshold of reference voltage source ref1, then peak current comparator 209 output upset, closes the second MOS transistor M2.

As preferred embodiment, described controllable silicon light modulation LED drive circuit comprise further one maximum service time timer 207, one or gate 208 and a rest-set flip-flop 205.

Described maximum service time timer 207 one end respectively electricity be connected to the output Q of described rest-set flip-flop 205 and the grid G of the second MOS transistor M2, described maximum service time the other end electricity of timer 207 be connected to an input that is described or gate 208; Another input electricity that is described or gate 208 is connected to the output of described peak current comparator 209, and output electricity that is described or gate 208 is connected to the reset terminal R of described rest-set flip-flop 205.When the electric current of described second MOS transistor M2 makes the output of described peak current comparator 209 overturn, or when described maximum service time, timer 207 detected that the service time of described second MOS transistor M2 reaches Preset Time, described or gate 208 output signal makes described rest-set flip-flop 205 reset, thus closes described second MOS transistor M2.Also, namely, in a power frequency period, when Vbus voltage is higher, peak current comparator 209 determines the shutoff moment of the second MOS transistor M2; When Vbus voltage is lower, maximum service time timer 207 determine the shutoff moment of the second MOS transistor M2.

As preferred embodiment, described controllable silicon light modulation LED drive circuit comprises a demagnetization detector 204 further; The input of described demagnetization detector 204 is connected with the source S electricity of described power switch MOS transistor M1, and its output electricity connects the set end S of described rest-set flip-flop 205.Described demagnetization detector 204 is for detecting the source voltage change of described power switch MOS transistor M1, and output signal makes the set of described rest-set flip-flop 205, thus opens described second MOS transistor M2.

As optional execution mode, described controllable silicon light modulation LED drive circuit comprises a switch drive module 206 further, it is serially connected between the output Q of rest-set flip-flop 205 and the second MOS transistor M2 grid, and be connected (when circuit does not arrange maximum service time timer 207, switch drive module 206 is connected with the output electricity of peak current comparator 209) with maximum service time timer 207 electricity.Switch drive module 206, according to the output signal of rest-set flip-flop 205, makes the second MOS transistor M2 close or conducting.

With reference to figure 3, the schematic diagram of voltage-dropping type controllable silicon light modulation LED drive system of the present invention.Described controllable silicon light modulation LED drive system comprises controllable silicon dimmer 202, rectifier bridge 203, bus capacitor C1, a sampling resistor R7 and controllable silicon light modulation LED drive circuit of the present invention (circuit as shown in Figure 2, same components symbol represents same or similar assembly).

Described controllable silicon dimmer 202 is connected with interchange input source 201 electricity, controls the brightness of LED load by adjusting himself angle of flow; Described rectifier bridge 203 is respectively with described controllable silicon dimmer 202 and exchange input source 201 electricity and be connected, and the sinusoidal signal rectification for exchanging input source 201 is an amplitude is positive voltage signal Vbus; Described bus capacitor C1 is coupled to two outputs of described rectifier bridge 203 and is connected with the drain D electricity of a power switch MOS transistor M1, for providing high-frequency current path for described power switch MOS transistor M1; The input of described high-high brightness hoisting module 21 is connected with the drain D electricity of described bus capacitor C1 and described power switch MOS transistor M1 respectively; The drain D of described second MOS transistor M2 is connected with the source S electricity of described power switch MOS transistor M1, and the source S of described second MOS transistor M2 is connected with described sampling resistor R7 electricity; Described peak current comparator 209 first input end is connected with described sampling resistor R7 electricity by described feedforward resistance R6; Described sampling resistor R7 is connected to LED load by inductance L 1 electricity.

The grid G of power switch MOS transistor M1 is coupled between the supplying resistance R1 of series connection and power supply electric capacity C2, simultaneously by a voltage stabilizing didoe ZD1 ground connection further.The further electricity in one end that sampling resistor R7 connects with inductance L 1 is connected to the negative electrode of a sustained diode 1, the negative terminal of the anode connection bus electric capacity C1 of sustained diode 1.LED load two ends also meet an output capacitance C4.In other embodiments, described sampling resistor R7 also can be connected to LED load by a transformer electricity.

As preferred embodiment, described controllable silicon light modulation LED drive circuit comprise further one maximum service time timer 207, one or gate 208 and a rest-set flip-flop 205; Described maximum service time timer 207 one end respectively electricity be connected to the output Q of described rest-set flip-flop 205 and the grid G of the second MOS transistor M2, described maximum service time the other end electricity of timer 207 be connected to an input that is described or gate 208; Another input electricity that is described or gate 208 is connected to the output of described peak current comparator 209, and output electricity that is described or gate 208 is connected to the reset terminal R of described rest-set flip-flop 205.When the electric current of described second MOS transistor M2 makes the output of described peak current comparator 209 overturn, or when described maximum service time, timer 207 detected that the service time of described second MOS transistor M2 reaches Preset Time, described or gate 208 output signal makes described rest-set flip-flop 205 reset, thus closes described second MOS transistor M2.

As preferred embodiment, described controllable silicon light modulation LED drive circuit comprises a demagnetization detector 204 further; The input of described demagnetization detector 204 is connected with the source S electricity of described power switch MOS transistor M1, and it exports the set end S of rest-set flip-flop 205 described in termination.Described demagnetization detector 204 is for detecting the source voltage change of described power switch MOS transistor M1, and output signal makes the set of described rest-set flip-flop 205, thus opens described second MOS transistor M2.

As optional execution mode, described controllable silicon light modulation LED drive circuit comprises a switch drive module 206 further, it is serially connected between the output Q of rest-set flip-flop 205 and the second MOS transistor M2 grid, and be connected (when circuit does not arrange maximum service time timer 207, switch drive module 206 is connected with the output electricity of peak current comparator 209) with maximum service time timer 207 electricity.Switch drive module 206, according to the output signal of rest-set flip-flop 205, makes the second MOS transistor M2 close or conducting.

LED drive circuit of the present invention uses source class type of drive.Electric current on sampling resistor R7 reflects the electric current on the second MOS transistor M2.Voltage on sampling resistor R7 is CS signal, and CS signal is connected to the first input end of peak current comparator 209 by feedforward resistance R6 electricity.When the second MOS transistor M2 opens, power switch MOS transistor M1 also conducting; Inductance L 1 electric current rises, and the voltage on sampling resistor R7 also rises; When the voltage on sampling resistor R7 and feedforward resistance R6 voltage sum reach reference voltage ref1 threshold values, the output upset of peak current comparator 209, or gate 208 output signal makes rest-set flip-flop 205 reset, switch drive module 206 outputs signal closedown second MOS transistor M2.M2 closes power switch MOS transistor M1 simultaneously and also closes, and sustained diode 1 starts conducting simultaneously, and inductance L 1 electric current starts to decline; When the electric current of inductance L 1 drops to zero, the drain voltage of power switch MOS transistor M1 also starts to decline; Due to M1 drain electrode and the capacitive coupling effect of source electrode, the source voltage of M1 also starts decline simultaneously; The detector 204 that now demagnetizes detects that the source voltage of M1 changes and outputs signal makes rest-set flip-flop 205 set, and driving switch driver module 206 makes the second MOS transistor M2 again open-minded.Maximum service time, timer 207 detected the service time of the second MOS transistor M2; When the service time of M2 is greater than systemic presupposition threshold values, output signal to or gate 208, rest-set flip-flop 205 is resetted, driving switch driver module 206 makes the second MOS transistor M2 close.Also, namely in a power frequency period, when Vbus voltage is higher, peak current comparator 209 determines the shutoff moment of the second MOS transistor M2; When Vbus voltage is lower, maximum service time timer 207 determine the shutoff moment of the second MOS transistor M2.

Below in conjunction with accompanying drawing 3-5, the operation principle of voltage-dropping type controllable silicon light modulation LED drive system of the present invention is described.

With reference to figure 4, the work typical waveform figure of voltage-dropping type controllable silicon light modulation LED drive system of the present invention, wherein solid line is circuit working waveform when not connecing controllable silicon dimmer 202, and dotted line is circuit working waveform when connecing controllable silicon dimmer 202.

Composition graphs 3, Fig. 4, when not connecing controllable silicon dimmer 202, the mean value of Vbus voltage is higher, and the voltage signal average value after upper divider resistance R2 and lower divider resistance R3 process is also higher; This voltage signal obtains a d. c. voltage signal Vdim after resistance R4 and filter capacitor C3 after filtering, and equally, when not connecing controllable silicon dimmer 202, this d. c. voltage signal Vdim is also higher.Operational amplifier 210 controls the conduction impedance of the first MOS transistor M3, and ensure during operational amplifier 210 Closed loop operation that two input terminal voltages are equal, thus input resistance R5 two ends can obtain a voltage, this voltage is Vdim-Vref2.Generation current on input resistance R5, its size is (Vdim-Vref2)/R5; This electric current flows through the first MOS transistor M3, and is injected into the input of peak current comparator 209.Because the input impedance of peak current comparator 209 is very high, this electric current all flows through feedforward resistance R6 and on R6, produces a DC offset voltage, and this DC offset voltage is added on CS voltage, makes the peak value V of CS voltage_{cS_TH}reduce, the peak current of inductance L 1 reduces, thus output current is reduced.

When connecing controllable silicon dimmer 202, if the maximum conduction angle degree of controllable silicon dimmer 202 is lower, then the mean value of Vbus voltage is also lower, as shown by dotted lines in figure 3.The d. c. voltage signal Vdim that this voltage signal obtains after upper divider resistance R2, lower divider resistance R3, filter resistance R4 and filter capacitor C3 process is also lower; Thus the voltage Vdim-Vref2 at input resistance R5 two ends is also lower; Electric current on input resistance R5 flows through the first MOS transistor M3 to feedforward resistance R6, and the DC offset voltage that R6 produces is also lower, makes the peak value V of CS voltage_{cS_TH}higher, the peak current of inductance is improved.Thus the maximum output current ratio that maximum output current when making circuit connect controllable silicon dimmer accounts for when not connecing controllable silicon dimmer improves.

When the angle of flow of controllable silicon dimmer 202 continues to reduce, Vdim voltage signal can continue to decline, until be less than Vref2 voltage, now, operational amplifier 210 cannot continue Closed loop operation, and the first MOS transistor M3 closes, input resistance R5 does not have electric current to flow through, feedforward resistance R6 does not have electric current to flow through yet, now feed forward circuit on inductance L 1 peak current without impact, the angle of flow change of what output current was linear follow controllable silicon dimmer.

Composition graphs 3, Fig. 5, wherein Fig. 5 is the Vdim voltage of controllable silicon light modulation LED drive system of the present invention and the graph of a relation of Vcs crest voltage.When Vdim voltage is higher than Vref2 voltage, the crest voltage V of Vcs_{cS_TH}decline, the peak current of inductance L 1 also declines; When Vdim voltage is less than Vref2 voltage, the crest voltage V of Vcs_{cS_TH}remain unchanged, the peak current of inductance L 1 also remains unchanged.

When using controllable silicon dimmer 202 light modulation, controllable silicon dimmer 202 provides dim signal by the mode changing angle of flow.When controllable silicon dimmer 202 blocks input voltage, Vbus voltage is output voltage Vout, and inductance L 1 electric current is also zero.When controllable silicon dimmer 202 conducting, Vbus voltage equals input voltage absolute value, and LED drive circuit normally works, for LED load provides energy.By changing the angle of flow of controllable silicon dimmer 202, the power of LED load changes, and realizes the object of light modulation.By high-high brightness hoisting module 21, improve maximum current during drive circuit connection controllable silicon dimmer 202; Eliminate leadage circuit simultaneously, use the input current of switch converters itself to provide the maintenance electric current of controllable silicon dimmer 202, improve LED drive circuit efficiency and system reliability.

Controllable silicon light modulation LED drive circuit of the present invention can be applied in buck-boost type controllable silicon light modulation LED drive system structure and in flyback controllable silicon light modulation LED drive system structure equally.With reference to figure 6, Fig. 7, wherein Fig. 6 is the schematic diagram of buck-boost type controllable silicon light modulation LED drive system of the present invention, and Fig. 7 is the schematic diagram of flyback controllable silicon light modulation LED drive system of the present invention.Wherein, the LED drive system of voltage-dropping type controllable silicon light modulation shown in the drive principle of controllable silicon light modulation LED drive system and control logic and Fig. 3 is similar, does not repeat them here.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (9)

1. a controllable silicon light modulation LED drive circuit, is characterized in that, comprising: one second MOS transistor, a peak current comparator, feedforward resistance, a reference voltage source and a high-high brightness hoisting module;

Described high-high brightness hoisting module comprises: an operational amplifier, one first MOS transistor and a reference voltage source; The first input end of described operational amplifier is the input of described high-high brightness hoisting module, in order to receive a sampled voltage signal, its second input is connected with the output electricity of described reference voltage source, its output electricity is connected to the grid of described first MOS transistor, described operational amplifier controls the conduction impedance of described first MOS transistor, ensures that two input terminal voltages are equal during described operational amplifier Closed loop operation; The source electrode electricity of described first MOS transistor is connected to the first input end of described operational amplifier, and its drain electrode is the output of described high-high brightness hoisting module, exports a current signal in order to control the output current of a LED drive circuit;

The drain electrode electricity of described second MOS transistor is connected to the source electrode of a power switch MOS transistor, and the source electrode electricity of described second MOS transistor connects a sampling resistor;

The output of described high-high brightness hoisting module is connected to described peak current comparator first input end and described feedforward resistance by the drain electrode electricity of described first MOS transistor, and the current signal that described first MOS transistor exports flows through feedforward resistance and produces direct current (DC) bias;

Described peak current comparator first input end is connected with sampling resistor electricity by described feedforward resistance, its second input is connected with the output electricity of described reference voltage source, its output is coupled to the grid of described second MOS transistor, described peak current comparator is used for the voltage magnitude sum of described feedforward resistance and sampling resistor to compare with the voltage threshold of described reference voltage source, controls conducting and the closedown of described second MOS transistor.

2. controllable silicon light modulation LED drive circuit according to claim 1, is characterized in that, described module comprises further: a voltage division processing unit and a filter unit; It is that positive voltage signal is gone forward side by side row relax that described voltage division processing unit receives outside amplitude; Described filter unit respectively electricity is connected to the first input end of described voltage division processing unit and described operational amplifier, described filter unit is used for carrying out filtering to the voltage signal after described voltage division processing cell processing, obtains the first input end that sampled voltage signal exports described operational amplifier to.

3. controllable silicon light modulation LED drive circuit according to claim 2, is characterized in that, described voltage division processing unit to comprise on one divider resistance and once divider resistance, and described filter unit comprises a filter resistance and a filter capacitor; It is positive voltage signal that described upper divider resistance one end receives outside amplitude, and the other end is connected with described lower divider resistance electricity, described lower divider resistance other end ground connection; Described filter resistance one end is coupled between described upper divider resistance and lower divider resistance, and the other end respectively electricity is connected to one end of described filter capacitor and the first input end of described operational amplifier, described filter capacitor other end ground connection.

4. controllable silicon light modulation LED drive circuit according to claim 3, is characterized in that, described module comprises further: an input resistance; Described input resistance is serially connected between the first input end of described filter resistance and described operational amplifier, and is connected with the source electrode electricity of described first MOS transistor, for obtaining dividing potential drop and exporting described first MOS transistor to.

5. the controllable silicon light modulation LED drive circuit according to Claims 1-4 any one, is characterized in that, described circuit comprise further one maximum service time timer, one or gate and a rest-set flip-flop;

Described maximum service time timer one end respectively electricity be connected to the output of described rest-set flip-flop and the grid of the second MOS transistor, described maximum service time the other end electricity of timer be connected to an input that is described or gate;

Another input electricity that is described or gate connects the output of described peak current comparator, and output electricity that is described or gate is connected to the reset terminal of described rest-set flip-flop;

When the electric current of described second MOS transistor makes the output of described peak current comparator overturn, or it is described when maximum service time, timer detected that the service time of described second MOS transistor reaches Preset Time, described or logic gate output signal makes described rest-set flip-flop reset, thus closes described second MOS transistor.

6. controllable silicon light modulation LED drive circuit according to claim 5, is characterized in that, described circuit comprises a demagnetization detector further; The input of described demagnetization detector is connected with the source electrode electricity of described power switch MOS transistor, its output electricity is connected to the set end of described rest-set flip-flop, described demagnetization detector is for detecting the source voltage change of described power switch MOS transistor, and output signal makes described rest-set flip-flop set, thus open described second MOS transistor.

7. a controllable silicon light modulation LED drive system, comprises a controllable silicon dimmer, a rectifier bridge, a bus capacitor and a sampling resistor, it is characterized in that, comprises the controllable silicon light modulation LED drive circuit described in Claims 1-4 any one further;

Described controllable silicon dimmer and one exchanges input source electricity and is connected, and controls the brightness of LED load by adjusting himself angle of flow;

Described rectifier bridge is respectively with described controllable silicon dimmer and exchange input source electricity and be connected, and the sinusoidal signal rectification for exchanging input source is an amplitude is positive voltage signal;

Described bus capacitor is coupled to two outputs of described rectifier bridge and is connected with the drain electrode electricity of a power switch MOS transistor, for providing high-frequency current path for described power switch MOS transistor;

The input of described high-high brightness hoisting module is connected with the drain electrode electricity of described bus capacitor and described power switch MOS transistor respectively; Described sampling resistor is connected to LED load by a transformer or inductance electricity.

8. controllable silicon light modulation LED drive system according to claim 7, is characterized in that, described controllable silicon light modulation LED drive circuit comprise further one maximum service time timer, one or gate and a rest-set flip-flop; Described maximum service time timer one end respectively electricity be connected to the output of described rest-set flip-flop and the grid of the second MOS transistor, described maximum service time the other end electricity of timer be connected to an input that is described or gate; Another input electricity that is described or gate is connected to the output of described peak current comparator, and output electricity that is described or gate is connected to the reset terminal of described rest-set flip-flop; When the electric current of described second MOS transistor makes the output of described peak current comparator overturn, or it is described when maximum service time, timer detected that the service time of described second MOS transistor reaches Preset Time, described or logic gate output signal makes described rest-set flip-flop reset, thus closes described second MOS transistor.

9. controllable silicon light modulation LED drive system according to claim 7, is characterized in that, described controllable silicon light modulation LED drive circuit comprises a demagnetization detector further; The input of described demagnetization detector is connected with the source electrode electricity of described power switch MOS transistor, its output electricity is connected to the set end of a rest-set flip-flop, described demagnetization detector is for detecting the source voltage change of described power switch MOS transistor, and output signal makes described rest-set flip-flop set, thus open described second MOS transistor.