CN204349778U

CN204349778U - LED drive circuit and switch power controller thereof

Info

Publication number: CN204349778U
Application number: CN201420866408.2U
Authority: CN
Inventors: 朱晓杰
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2014-12-30
Filing date: 2014-12-30
Publication date: 2015-05-20
Anticipated expiration: 2024-12-30

Abstract

The utility model provides a kind of LED drive circuit and switch power controller thereof, and this switch power controller comprises: power drive pipe; Grid zero cross detection circuit, by the grid inflow current of detection power driving tube to realize the zero passage detection of inductive current, in response to described inductive current zero passage, described grid zero cross detection circuit exports zero passage detection signal; Drive circuit, produces drive singal according to zero passage detection signal, and in response to zero passage detection signal, drive singal controls the conducting of power drive pipe.The electric current flowing into the grid of power drive pipe when the utility model is by detecting inductance zero passage realizes the zero passage detection of inductive current, and drive singal can Direct driver power drive pipe, and circuit is simple, and it is convenient to realize, and dramatically saves on circuit cost.

Description

LED drive circuit and switch power controller thereof

Technical field

The utility model relates to switch power technology, particularly relates to a kind of LED drive circuit and switch power controller thereof.

Background technology

As shown in Figure 1, the buck configuration LED drive circuit of traditional employing source pole driving mode comprises resistance R1, electric capacity C2, sustained diode 1, output capacitance C1, inductance L 1, first power switch M1, sampling resistor Rcs and switch power controller 100.Switch power controller comprises the second power switch M2, zero cross detection circuit 101, logic and driver circuitry 102, comparator 103 and rest-set flip-flop 104.Wherein the first power switch M1 is high-voltage circuit breaker, second power switch M2 is drived control switch, zero cross detection circuit 101 detects the voltage signal of the second power switch M2 drain terminal, and drive singal GT controls the second power switch M2 to realize the switch control rule of system.

Fig. 2 shows the work schedule of circuit shown in Fig. 1, composition graphs 1 and Fig. 2, during the second power switch M2 conducting, first power switch M1 also conducting, input current flows through output capacitance C1 and output end vo ut, inductance L 1, first power switch M1, the second power switch M2, sampling resistor Rcs, electric current in inductance L 1 increases, inductance L 1 stored energy; When second power switch M2 turns off, the first power switch M1 also turns off, and the electric current in inductance L 1 is through sustained diode 1 afterflow, and electric current in inductance L 1 reduces, and inductance L 1 releases energy output capacitance C1 and output end vo ut.

When the electric current in inductance L 1 reduces to zero, the drain terminal of the first power switch M1 can produce resonance, resonating conductive is to the drain terminal of the second power switch M2, voltage VA is declined gradually, zero cross detection circuit 101, by inner comparator comparative voltage VDD and voltage VA, detects the zero crossing of the electric current flowing through inductance L 1, produces zero passage detection signal ZCD to rest-set flip-flop circuit 104, through logic and driver circuitry 102, again open power switch M1 and M2.

Power switch M1 and M2 repeats switch motion above, circuit continuous firing, and LED drive circuit is in critical current mode conducting state all the time.

In the system of employing source drive traditional described in Fig. 1, when utilizing inductance zero passage, the mode detecting the drain terminal change in voltage of the second power switch M2 realizes zero passage detection, and principle is comparatively simple, easily realizes.But there is the shortcoming that must use the second power switch M2, cause circuit area to increase, cost increases.

Utility model content

Problem to be solved in the utility model is to provide a kind of LED drive circuit and switch power controller thereof, the electric current flowing into the grid of power drive pipe during by detecting inductance zero passage realizes the zero passage detection of inductive current, drive singal can Direct driver power drive pipe and without the need to extra driving switch, circuit is simple, it is convenient to realize, and dramatically saves on circuit cost.

For solving the problems of the technologies described above, the utility model provides a kind of switch power controller of LED drive circuit, comprising:

Power drive pipe, the inductance in described LED drive circuit forms current path via described power drive pipe;

Grid zero cross detection circuit, its input connects the grid of described power drive pipe, by detecting the grid inflow current of described power drive pipe to realize flowing through the zero passage detection of the inductive current of described inductance, in response to described inductive current zero passage, described grid zero cross detection circuit exports zero passage detection signal;

Drive circuit, produce drive singal according to described zero passage detection signal, described drive singal transfers to the grid of described power drive pipe, and in response to described zero passage detection signal, described drive singal controls the conducting of described power drive pipe.

According to an embodiment of the present utility model, described switch power controller also comprises:

Comparator circuit, sampling obtains sampled voltage and it is compared with the first reference voltage preset, and exceedes described first reference voltage in response to described sampled voltage, and described comparator circuit exports cut-off signals, and described sampled voltage corresponds to described inductive current;

Described drive circuit also produces described drive singal according to described cut-off signals, and in response to described cut-off signals, described drive singal controls described power drive pipe and turns off.

According to an embodiment of the present utility model, described grid zero cross detection circuit comprises:

Current mirror comparator, produces comparative voltage according to described grid inflow current;

Zero passage detection signal generating circuit, compares described comparative voltage with the second reference voltage preset, and generates described zero passage detection signal according to comparative result.

According to an embodiment of the present utility model, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

First triode, its collector electrode connects the second end of described first current source, and its emitter connects the grid of described power drive pipe, and the collector electrode of described first triode exports described comparative voltage;

Second triode, its collector electrode connects the second end of described second current source, and its base stage connects the collector electrode of described second triode and the base stage of described first triode, its grounded emitter.

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

First metal-oxide-semiconductor, its source electrode connects the second end of described first current source, and its grid connects the grid of described power drive pipe, its grounded drain, and the source electrode of described first metal-oxide-semiconductor exports described comparative voltage;

Second metal-oxide-semiconductor, its source electrode connects the second end of described second current source, and its grid connects the source electrode of described second metal-oxide-semiconductor and ground connection.

According to an embodiment of the present utility model, described zero passage detection signal generating circuit comprises:

Comparator, its first input end receives described comparative voltage, and its second input receives described second reference voltage;

NOR gate, its first input end connects the output of described comparator, and its second input receives described drive singal, and its output exports described zero passage detection signal.

3rd metal-oxide-semiconductor, its source electrode connects power supply, and its grid receives described comparative voltage;

3rd current source, its first end connects the drain electrode of described 3rd metal-oxide-semiconductor, its second end ground connection;

Schmidt trigger, its input connects the drain electrode of described 3rd metal-oxide-semiconductor;

NOR gate, its first input end connects the output of described Schmidt trigger, and its second input receives described drive singal, and its output exports described zero passage detection signal.

According to an embodiment of the present utility model, described switch power controller also comprises: high voltage startup power supply circuits, and its first end connects the drain electrode of described power drive pipe, and its second end is via power supply capacity earth.

Comparator circuit, its first input end connects the second end of described high voltage startup power supply circuits, and its second input receives the first reference voltage preset, and its output exports cut-off signals;

According to an embodiment of the present utility model, described drive circuit comprises:

Rest-set flip-flop, its set input receives described zero passage detection signal, and its RESET input receives described cut-off signals;

Logic and driver circuitry, its input connects the output of described rest-set flip-flop, and its output exports described drive singal.

According to an embodiment of the present utility model, described logic and driver circuitry comprises:

4th metal-oxide-semiconductor, its source electrode connects power supply, and its grid connects the output of described rest-set flip-flop, and its drain electrode exports described drive singal;

5th metal-oxide-semiconductor, its source ground, its grid connects the output of described rest-set flip-flop, and its drain electrode connects the drain electrode of described 4th metal-oxide-semiconductor via resistance.

According to an embodiment of the present utility model, described logic and driver circuitry also comprises:

6th metal-oxide-semiconductor, its source ground, its grid receive delay signal, its drain electrode connects the drain electrode of described 4th metal-oxide-semiconductor, and described inhibit signal postpones Preset Time by the output end signal of described rest-set flip-flop and obtains.

For solving the problems of the technologies described above, the utility model provides a kind of LED drive circuit, comprises the switch power controller described in above-mentioned any one.

In order to solve the problems of the technologies described above, the utility model additionally provides a kind of LED drive circuit, comprising:

Fly-wheel diode, its negative electrode connects input voltage incoming end;

Output capacitance, its first end connects the negative electrode of described fly-wheel diode;

Inductance, its first end connects the anode of described fly-wheel diode, and its second end connects the second end of described output capacitance;

Switch power controller, described switch power controller comprises:

Power drive pipe, its drain electrode connects the first end of described inductance, and its source electrode is via sampling resistor ground connection;

Comparator circuit, sampling obtains the sampled voltage at described sampling resistor two ends and it is compared with the first reference voltage preset, and exceedes described first reference voltage in response to described sampled voltage, and described comparator circuit exports cut-off signals;

Drive circuit, drive singal is produced according to described zero passage detection signal and cut-off signals, described drive singal transfers to the grid of described power drive pipe, in response to described zero passage detection signal, described drive singal controls the conducting of described power drive pipe, in response to described cut-off signals, described drive singal controls described power drive pipe and turns off.

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

Second metal-oxide-semiconductor, its source electrode connects the second end of described second current source, and its grid connects the drain electrode of described second metal-oxide-semiconductor and ground connection.

According to an embodiment of the present utility model, described logic and driver circuitry also comprises: the 6th metal-oxide-semiconductor, its source ground, its grid receive delay signal, its drain electrode connects the drain electrode of described first metal-oxide-semiconductor, and described inhibit signal postpones Preset Time by the output end signal of described rest-set flip-flop and obtains.

Fly-wheel diode, its plus earth;

Sampling resistor, its first end connects the negative electrode of described fly-wheel diode, and its second end is connected to floating ground;

Inductance, its first end connects the second end of described sampling resistor;

Output capacitance, its first end connects the second end of described inductance, and its second end connects the anode of described fly-wheel diode and ground connection;

Switch power controller, described switch power controller comprises:

Power drive pipe, its drain electrode connects input voltage incoming end, and its source electrode connects the first end of described sampling resistor and the negative electrode of described fly-wheel diode;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

According to an embodiment of the present utility model, described switch power controller also comprises: high voltage startup power supply circuits, and its first end connects the drain electrode of described power drive pipe, and its second end is connected to floating ground via power supply electric capacity.

Fly-wheel diode, its plus earth, its negative electrode is connected to floating ground;

Sampling resistor, its first end connects the negative electrode of described fly-wheel diode;

Switch power controller, described switch power controller comprises:

Power drive pipe, its drain electrode connects input voltage incoming end, and its source electrode is connected to floating ground;

Comparator circuit, its first input end connects the second end of described sampling resistor, its second input receives the first reference voltage preset, described comparator circuit sampling obtains the sampled voltage at described sampling resistor two ends and it is compared with described first reference voltage, exceed described first reference voltage in response to described sampled voltage, described comparator circuit exports cut-off signals;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

Fly-wheel diode, its negative electrode connects input voltage incoming end;

Switch power controller, described switch power controller comprises:

High voltage startup power supply circuits, its first end connects the drain electrode of described power drive pipe, and its second end is via power supply capacity earth;

Comparator circuit, its first input end connects the second end of described high voltage startup power supply circuits, and its second input receives the reference voltage preset, and its output exports cut-off signals;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

Compared with prior art, the utility model has the following advantages:

In the switch power controller of the utility model embodiment, drive singal Direct driver power drive pipe, the zero passage detection of inductive current is realized by the grid inflow current of power drive pipe during detection inductive current zero passage, circuit is simple, it is convenient to realize, eliminate the drived control switch in traditional source electrode driving LED drive circuit, dramatically saves on circuit cost.

Accompanying drawing explanation

Fig. 1 is the circuit diagram of the voltage-dropping type LED drive circuit of a kind of source drive in prior art;

Fig. 2 is the working signal oscillogram of LED drive circuit shown in Fig. 1;

Fig. 3 is the circuit diagram of the LED drive circuit according to the utility model first embodiment;

Fig. 4 is the circuit diagram of a kind of grid zero cross detection circuit according to the utility model first embodiment and logic and driver circuitry;

Fig. 5 is the working signal oscillogram of the zero cross detection circuit of grid shown in Fig. 4;

Fig. 6 is the circuit diagram of another kind of grid zero cross detection circuit according to the utility model first embodiment and logic and driver circuitry;

Fig. 7 is the circuit diagram of another grid zero cross detection circuit according to the utility model first embodiment and logic and driver circuitry;

Fig. 8 is the circuit diagram of the LED drive circuit according to the utility model second embodiment;

Fig. 9 is the circuit diagram of the LED drive circuit according to the utility model the 3rd embodiment;

Figure 10 is the circuit diagram of the LED drive circuit according to the utility model the 4th embodiment.

Embodiment

Below in conjunction with specific embodiments and the drawings, the utility model is described in further detail, but should not limit protection range of the present utility model with this.

First embodiment

With reference to figure 3, the LED drive circuit of the first embodiment comprises: sustained diode 1, output capacitance C1, inductance L 1, sampling resistor Rcs, power supply electric capacity C2 and switch power controller 300.Switch power controller 300 comprises power drive pipe M1, grid zero cross detection circuit 301, comparator circuit 303, drive circuit 310 and high voltage startup power supply circuits 305.

Wherein, the negative electrode of sustained diode 1 connects input voltage incoming end Vin, to receive input voltage; The first end of output capacitance D1 connects the negative electrode of sustained diode 1; The first end of inductance L 1 connects the anode of sustained diode 1, and the second end of inductance L 1 connects second end of output capacitance C1.

The drain electrode of power drive pipe M1 connects the first end of inductance L 1, and its source electrode is connected to ground via sampling resistor Rcs.Power drive pipe M1 is high-voltage circuit breaker, is equivalent to the first power switch M1 in Fig. 1.Compared to the circuit in Fig. 1, the present embodiment eliminates drived control switch, also namely eliminates the second power switch M2 in Fig. 1.

The input of grid zero cross detection circuit 301 connects the grid of power drive pipe M1, by the grid inflow current of detection power driving tube M1 to realize the zero passage detection of the inductive current of inductance L 1.In response to inductive current zero passage, grid zero cross detection circuit 301 exports zero passage detection signal ZCD.

Comparator circuit 303 sampling obtains the sampled voltage CS at sampling resistor Rcs two ends, and is compared with the reference voltage Vr1 preset by sampled voltage CS, and exceed reference voltage Vr1 in response to sampled voltage CS, comparator circuit 303 exports cut-off signals.

Drive circuit 310 produces drive singal GT according to zero passage detection signal ZCD and cut-off signals, and drive singal GT transfers to the grid of power drive pipe M1.Specifically, control power drive pipe M1 conducting in response to zero passage detection signal ZCD, drive singal GT, in response to cut-off signals, drive singal GT controls power drive pipe M1 and turns off.

As a nonrestrictive example, drive circuit 310 can comprise rest-set flip-flop 304 and logic and driver circuitry 302.Wherein, the set input of rest-set flip-flop 304 connects the output of grid zero cross detection circuit 301 to receive zero passage detection signal ZCD, and the RESET input connects the output of comparator circuit 303 to receive cut-off signals.The input of logic and driver circuitry 302 connects the output of rest-set flip-flop 304, output output drive signal GT.

One end of high voltage startup power supply circuits 305 connects the drain D RAIN of power drive pipe M1, and the other end is via power supply electric capacity C2 ground connection.High voltage startup power supply circuits 305 for providing the electric current needed for circuit, holding circuit work time operating voltage.

The detailed circuit of a kind of grid zero cross detection circuit 401 and logic and driver circuitry 402 is shown with reference to figure 4, Fig. 4.

Grid zero cross detection circuit 401 comprises: current mirror comparator 404, produces comparative voltage VC according to grid input current; Zero passage detection signal generating circuit 403, compares comparative voltage VC with the reference voltage Vref preset, and generates zero passage detection signal ZCD according to comparative result.

Furthermore, current mirror comparator 404 can comprise: the first current source 413, and its first end connects power supply; Second current source 414, its first end connects power supply; Triode 411, its collector electrode connects the second end of the first current source 413, and its emitter connects the grid of power drive pipe M1, and the collector electrode of triode 411 exports comparative voltage VC, and triode 411 can be NPN triode; Triode 412, its collector electrode connects the second end of the second current source 414, the collector electrode of its base stage connecting triode 412 and the base stage of triode 411, its grounded emitter, and triode 412 also can be NPN triode.

Zero passage detection signal generating circuit 403 can comprise: comparator 415, and its first input end receives comparative voltage VC, and its second input receives the reference voltage Vref preset; NOR gate 416, its first input end connects the output of comparator 415, and its second input receives drive singal GT, and its output exports zero passage detection signal ZCD.

Logic and driver circuitry 402 can comprise: metal-oxide-semiconductor 417, and its source electrode connects power supply, and its grid connects the output of rest-set flip-flop, its drain electrode output drive signal GT; Metal-oxide-semiconductor 418, its source ground, its grid connects the output of rest-set flip-flop, and its drain electrode connects the drain electrode of metal-oxide-semiconductor 417 via resistance RS; Metal-oxide-semiconductor 419, its source ground, its grid receive delay signal, its drain electrode connects the drain electrode of metal-oxide-semiconductor 417, and this inhibit signal postpones a Preset Time by the output end signal of rest-set flip-flop and obtains.

When the output signal of rest-set flip-flop makes the drain signal of metal-oxide-semiconductor 417 and metal-oxide-semiconductor 418 overturn from high to low, metal-oxide-semiconductor 419 can be opened simultaneously, and certain hour is maintained under the effect of inhibit signal, in this Preset Time, drive singal GT is dragged down via metal-oxide-semiconductor 419, prevents saltus step and the shake of drive singal GT, after Preset Time, metal-oxide-semiconductor 419 is closed, to enter the state of zero passage detection.

Fig. 5 shows the signal waveform of the grid zero cross detection circuit in Fig. 4, is described the operation principle of the LED drive circuit of the present embodiment below in conjunction with Fig. 3 to Fig. 5.

The LED drive circuit of the present embodiment is buck configuration, and power drive pipe M1 is directly controlled by drive singal GT.When drive singal GT is logic high, power drive pipe M1 conducting, input voltage incoming end forms current path via output capacitance C1 and output end vo ut, inductance L 1, power drive pipe M1, sampling resistor Rcs, the inductive current flowing through inductance L 1 increases, inductance L 1 stored energy, the sampled voltage CS on sampling resistor Rcs rises, when the sampled voltage CS on sampling resistor Rcs reaches the reference voltage Vr1 that comparator circuit 303 receives, export cut-off signals, this cut-off signals makes drive singal GT be logic low via drive circuit 310, power drive pipe M1 turns off, flow through the inductive current of inductance L 1 through sustained diode 1 afterflow, the inductive current flowing through inductance L 1 reduces, and inductance L 1 releases energy output capacitance C1 and output, when the inductive current flowing through inductance L 1 reduces to zero, the drain D RAIN of power drive pipe M1 can produce resonance, owing to there is gate-drain parasitic capacitances Ciss between the drain D RAIN of power drive pipe M1 and grid, and the voltage at gate-drain parasitic capacitances Ciss two ends can not suddenly change, therefore, when the voltage resonance of drain D RAIN declines, have electric current I d from ground GND through metal-oxide-semiconductor 418, resistance RS, gate-drain parasitic capacitances Ciss flows into drain D RAIN, now will produce negative voltage difference Vd between the grid of power drive pipe M1 and ground, Vd=Id* (RS+Ron1), impedance when wherein Ron1 is metal-oxide-semiconductor 418 conducting, Id is the current value of electric current I d, RS is the resistance value of resistance RS.

Grid zero cross detection circuit flows into the grid inflow current of power drive pipe M1 grid by detecting, realize the zero passage detection of inductive current in other words by detecting voltage difference Vd.As mentioned above, along with the generation of the drain electrode resonance of power drive pipe M1, drain voltage can decline gradually, electric current I d also can increase gradually, voltage difference Vd between the grid of power drive pipe M1 and ground GND also increases gradually, and the comparative voltage VC that current mirror comparator 404 exports can be pulled down by logic high, as VC<Vref, the output signal upset of comparator 415, thus export zero passage detection signal ZCD.Zero passage detection ZCD signal, again via rest-set flip-flop 304 and logic and driver circuitry 302, makes drive singal GT be logic high, controls power drive pipe M1 conducting.

Then, power drive pipe M1 repeats shutoff above and opens action, and circuit just always works in critical conduction mode.

The detailed circuit of another kind of grid zero cross detection circuit 401 and logic and driver circuitry 402 is shown with reference to figure 6, Fig. 6.

Zero passage detection signal generating circuit 403 can comprise: metal-oxide-semiconductor 420, and its source electrode connects power supply, and its grid receives comparative voltage; 3rd current source 423, its first end connects the drain electrode of metal-oxide-semiconductor 420, its second end ground connection; Schmidt trigger 421, its input connects the drain electrode of metal-oxide-semiconductor 420; NOR gate 422, its first input end connects the output of Schmidt trigger 421, and its second input receives drive singal GT, and its output exports zero passage detection signal ZCD.

The detailed circuit of another grid zero cross detection circuit 401 and logic and driver circuitry 402 is shown with reference to figure 7, Fig. 7.Compared to Fig. 6, the current mirror comparator 404 in grid zero cross detection circuit 401 have employed different structures.

Specifically, grid zero cross detection circuit 401 comprises: current mirror comparator 404, produces comparative voltage VC according to grid input current; Zero passage detection signal generating circuit 403, compares comparative voltage VC with the reference voltage Vref preset, and generates zero passage detection signal ZCD according to comparative result.

Furthermore, current mirror comparator 404 can comprise: the first current source 413, and its first end connects power supply; Second current source 414, its first end connects power supply; Metal-oxide-semiconductor 411, its source electrode connects the second end of the first current source 413, and its grid connects the grid of power drive pipe M1, its grounded drain, and the source electrode of metal-oxide-semiconductor 411 exports described comparative voltage, and this metal-oxide-semiconductor 411 can be such as PMOS; Metal-oxide-semiconductor 412, its source electrode connects the second end of the second current source 414, and its grid connects the drain electrode of metal-oxide-semiconductor 412 and ground connection, and metal-oxide-semiconductor 412 also can be PMOS.

Second embodiment

With reference to figure 8, the LED drive circuit of the second embodiment is floating ground structure, comprising: sustained diode 1, output capacitance C1, inductance L 1, sampling resistor Rcs, power supply electric capacity C2 and switch power controller 300.Switch power controller 300 comprises power drive pipe M1, grid zero cross detection circuit 301, comparator circuit 303, logic and driver circuitry 302, rest-set flip-flop 304 and high voltage startup power supply circuits 305.

In second embodiment, the internal structure of switch power controller 300 is identical with the first embodiment, and difference is only that the ground of switch power controller 300 is for floating ground, not identical with the ground of input voltage.

Peripheral circuit connected mode beyond second embodiment breaker in middle power-supply controller of electric 300 is different from the first embodiment, in addition, the connected mode of these peripheral circuits and power drive pipe M1 is also different from the first embodiment, inductance L 1, output capacitance C1, sustained diode 1 by global transfer to one end of sampling resistor Rcs.

Specifically, the plus earth of sustained diode 1; The first end of sampling resistor Rcs connects the negative electrode of sustained diode 1, and the second end is connected to floating ground; The first end of inductance L 1 connects second end of sampling resistor Rcs; The first end of output capacitance C1 connects the second end of inductance L 1, and the second end connects the anode of sustained diode 1 and ground connection; The drain electrode of power drive pipe M1 connects input voltage incoming end Vin, and its source electrode connects the first end of sampling resistor Rcs and the negative electrode of sustained diode 1.

Operation principle and first embodiment of the LED drive circuit of the second embodiment are similar, and the more details about the LED drive circuit of the second embodiment refer to the first embodiment, repeat no more here.

3rd embodiment

With reference to figure 9, the LED drive circuit of the 3rd embodiment is another kind of floating ground structure, comprising: sustained diode 1, output capacitance C1, inductance L 1, sampling resistor Rcs, power supply electric capacity C2 and switch power controller 500.Switch power controller 500 comprises power drive pipe M1, grid zero cross detection circuit 501, comparator circuit 503, logic and driver circuitry 502, rest-set flip-flop 504 and high voltage startup power supply circuits 505.

In 3rd embodiment, the internal structure of switch power controller 500 is identical with the first embodiment, and difference is mainly that the ground of switch power controller 500 is for floating ground, not identical with the ground of input voltage.Specifically, high voltage startup power supply circuits 505 are connected to floating ground via power supply electric capacity C2, and the source electrode of power drive pipe M1 is connected to floating ground.

Peripheral circuit connected mode beyond 3rd embodiment breaker in middle power-supply controller of electric 500 is different from the first embodiment, in addition, the connected mode of these peripheral circuits and power drive pipe M1, comparator circuit 503 is also different from the first embodiment, inductance L 1, output capacitance C1, sustained diode 1 by global transfer to one end of sampling resistor Rcs.

Specifically, the negative electrode of sustained diode 1 is connected to floating ground, the plus earth of sustained diode 1; The first end of sampling resistor Rcs connects the negative electrode of sustained diode 1, and the second end is connected to comparator circuit 503; The first end of inductance L 1 connects second end of sampling resistor Rcs; The first end of output capacitance C1 connects the second end of inductance L 1, and the second end connects the anode of sustained diode 1 and ground connection; The drain electrode of power drive pipe M1 connects input voltage incoming end Vin, and its source electrode is connected to floating ground.

Operation principle and first embodiment of the LED drive circuit of the 3rd embodiment are similar, and the more details about the LED drive circuit of the 3rd embodiment refer to the first embodiment, repeat no more here.

4th embodiment

With reference to Figure 10, the LED drive circuit of the 4th embodiment comprises: sustained diode 1, output capacitance C1, inductance L 1, sampling resistor Rcs, power supply electric capacity C2 and switch power controller 700.Switch power controller 700 comprises power drive pipe M1, grid zero cross detection circuit 701, comparator circuit 703, logic and driver circuitry 702, rest-set flip-flop 704 and high voltage startup power supply circuits 705.

In 4th embodiment, the internal structure of switch power controller 700 is substantially identical with the first embodiment, and difference is mainly that the connected mode of comparator circuit 703 is different.Specifically, the first input end of comparator circuit 703 connects the second end of high voltage startup power supply circuits 705, second input of comparator circuit 703 receives the reference voltage Vr1 preset, and the output of comparator circuit 703 exports cut-off signals the RESET input to rest-set flip-flop 704.

Peripheral circuit connected mode beyond 4th embodiment breaker in middle power-supply controller of electric 700 is substantially identical with the first embodiment.

Operation principle and first embodiment of the LED drive circuit of the 4th embodiment are similar, and the more details about the LED drive circuit of the 4th embodiment refer to the first embodiment, repeat no more here.

By upper, in LED drive circuit of the present utility model, drive singal Direct driver power drive pipe, circuit realizes the zero passage detection of inductive current by the grid inflow current of power drive pipe during detection inductive current zero passage, well can be applied in the Switching Power Supply structure of critical current mode conduction mode.

LED drive circuit circuit of the present utility model is simple, realization is convenient, eliminates the drived control switch that traditional source electrode Drive Structure needs, dramatically saves on circuit cost.

The above is only preferred embodiment of the present utility model, not does any pro forma restriction to the utility model.Therefore, every content not departing from technical solutions of the utility model, just according to technical spirit of the present utility model to any simple amendment made for any of the above embodiments, equivalent conversion, all still belong in the protection range of technical solutions of the utility model.

Claims

1. a switch power controller for LED drive circuit, is characterized in that, comprising:

2. switch power controller according to claim 1, is characterized in that, also comprises:

3. switch power controller according to claim 1, is characterized in that, described grid zero cross detection circuit comprises:

4. switch power controller according to claim 3, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

5. switch power controller according to claim 3, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

6. the switch power controller according to claim 4 or 5, is characterized in that, described zero passage detection signal generating circuit comprises:

7. the switch power controller according to claim 4 or 5, is characterized in that, described zero passage detection signal generating circuit comprises:

8. switch power controller according to claim 1, is characterized in that, also comprises:

High voltage startup power supply circuits, its first end connects the drain electrode of described power drive pipe, and its second end is via power supply capacity earth.

9. switch power controller according to claim 8, is characterized in that, also comprises:

10. the switch power controller according to claim 2 or 9, is characterized in that, described drive circuit comprises:

11. switch power controllers according to claim 10, is characterized in that, described logic and driver circuitry comprises:

12. switch power controllers according to claim 11, is characterized in that, described logic and driver circuitry also comprises:

13. 1 kinds of LED drive circuits, is characterized in that, comprise the switch power controller according to any one of claim 1 to 12.

14. 1 kinds of LED drive circuits, is characterized in that, comprising:

Fly-wheel diode, its negative electrode connects input voltage incoming end;

Switch power controller, described switch power controller comprises:

15. LED drive circuits according to claim 14, is characterized in that, described grid zero cross detection circuit comprises:

16. LED drive circuits according to claim 15, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

17. LED drive circuits according to claim 15, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

18. LED drive circuits according to claim 16 or 17, it is characterized in that, described zero passage detection signal generating circuit comprises:

19. LED drive circuits according to claim 16 or 17, it is characterized in that, described zero passage detection signal generating circuit comprises:

20. LED drive circuits according to claim 17, is characterized in that, described drive circuit comprises:

21. LED drive circuits according to claim 20, is characterized in that, described logic and driver circuitry comprises:

22. LED drive circuits according to claim 21, is characterized in that, described logic and driver circuitry also comprises:

6th metal-oxide-semiconductor, its source ground, its grid receive delay signal, its drain electrode connects the drain electrode of described first metal-oxide-semiconductor, and described inhibit signal postpones Preset Time by the output end signal of described rest-set flip-flop and obtains.

23. LED drive circuits according to claim 14, is characterized in that, described switch power controller also comprises:

24. 1 kinds of LED drive circuits, is characterized in that, comprising:

Fly-wheel diode, its plus earth;

Switch power controller, described switch power controller comprises:

25. LED drive circuits according to claim 24, is characterized in that, described grid zero cross detection circuit comprises:

26. LED drive circuits according to claim 25, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

27. LED drive circuits according to claim 25, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

28. LED drive circuits according to claim 26 or 27, it is characterized in that, described zero passage detection signal generating circuit comprises:

29. LED drive circuits according to claim 26 or 27, it is characterized in that, described zero passage detection signal generating circuit comprises:

30. LED drive circuits according to claim 27, is characterized in that, described drive circuit comprises:

31. LED drive circuits according to claim 30, is characterized in that, described logic and driver circuitry comprises:

32. LED drive circuits according to claim 31, is characterized in that, described logic and driver circuitry also comprises:

33. LED drive circuits according to claim 24, is characterized in that, described switch power controller also comprises:

High voltage startup power supply circuits, its first end connects the drain electrode of described power drive pipe, and its second end is connected to floating ground via power supply electric capacity.

34. 1 kinds of LED drive circuits, is characterized in that, comprising:

Switch power controller, described switch power controller comprises:

35. LED drive circuits according to claim 34, is characterized in that, described grid zero cross detection circuit comprises:

36. LED drive circuits according to claim 35, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

37. LED drive circuits according to claim 35, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

38. LED drive circuits according to claim 36 or 37, it is characterized in that, described zero passage detection signal generating circuit comprises:

39. LED drive circuits according to claim 36 or 37, it is characterized in that, described zero passage detection signal generating circuit comprises:

40., according to LED drive circuit according to claim 37, is characterized in that, described drive circuit comprises:

41. LED drive circuits according to claim 40, is characterized in that, described logic and driver circuitry comprises:

42. LED drive circuits according to claim 41, is characterized in that, described logic and driver circuitry also comprises:

43. LED drive circuits according to claim 34, is characterized in that, described switch power controller also comprises:

44. 1 kinds of LED drive circuits, is characterized in that, comprising:

Fly-wheel diode, its negative electrode connects input voltage incoming end;

Switch power controller, described switch power controller comprises:

45. LED drive circuits according to claim 44, is characterized in that, described grid zero cross detection circuit comprises:

46. LED drive circuits according to claim 45, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

47. LED drive circuits according to claim 45, is characterized in that, described current mirror comparator comprises:

First current source, its first end connects power supply;

Second current source, its first end connects power supply;

48. LED drive circuits according to claim 46 or 47, it is characterized in that, described zero passage detection signal generating circuit comprises:

49. LED drive circuits according to claim 46 or 47, it is characterized in that, described zero passage detection signal generating circuit comprises:

50. LED drive circuits according to claim 47, is characterized in that, described drive circuit comprises:

51. LED drive circuits according to claim 50, is characterized in that, described logic and driver circuitry comprises:

52. LED drive circuits according to claim 51, is characterized in that, described logic and driver circuitry also comprises: