CN204086510U - Demagnetization detection control module and demagnetization detection system - Google Patents
Demagnetization detection control module and demagnetization detection system Download PDFInfo
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- CN204086510U CN204086510U CN201420464827.3U CN201420464827U CN204086510U CN 204086510 U CN204086510 U CN 204086510U CN 201420464827 U CN201420464827 U CN 201420464827U CN 204086510 U CN204086510 U CN 204086510U
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Abstract
The utility model discloses demagnetization detection control module and demagnetization detection system.Wherein, a kind of demagnetization detection system, comprises demagnetization detection control module; Demagnetization detection control module is coupled between the source electrode of power switch pipe and peak point current sampling unit by the input end of peak value comparison method unit, is connected the grid of power switch pipe by the output terminal of driver element; When the voltage on peak point current sampling unit arrives a reference voltage, by peak value comparison method unit, switching signal generating unit and driver element switch-off power switching tube; After power switch pipe turns off a lasting Preset Time, the grid being controlled power switch pipe by logical circuit and driver element becomes high-impedance state over the ground, and utilizes the stray capacitance of power switch pipe to detect demagnetization signal; When the grid voltage of power switch pipe is less than reference voltage source, export demagnetization detection signal by comparer.The utility model realizes demagnetization by the drain voltage of the drain-gate capacitance coupled power switching tube of power switch pipe parasitism and detects, and the cost of demagnetization detection mode is low, and peripheral circuit is simple.
Description
Technical field
The utility model relates to the demagnetization detection technique field in Switching Power Supply, particularly relates to a kind of being used in without the demagnetization detection control module in the raster data model LED power scheme of auxiliary winding and demagnetization detection system.
Background technology
The function of LED drive power is to provide the constant output current of LED, and in the Switching Power Supply that critical continuous mode or discontinuous mode control, the de-magnetization point of probe current is most important.Existing de-magnetization point detection mode is that winding (inductor winding or Transformer Winding) is assisted on increase by tunnel, detects de-magnetization point by magnetic-coupled mode; When the electric current in main power inductance is reduced to zero, the voltage vanishing at auxiliary winding two ends, the existing demagnetization change detected by detecting voltage realizes the function detected of demagnetizing.
Fig. 1 is the realizing circuit figure that the demagnetization of existing LED drive power detects.As shown in Figure 1, input power S is connected to two input ends of the rectifier bridge that four diodes (D1-D4) form; After output capacitance Cout is in parallel with pull-up resistor Rload, between the output terminal being coupled in rectifier bridge and main power inductance Lm; Input capacitance Cin is coupled on two output terminals of rectifier bridge; Commutation diode D1 one end is coupled between input capacitance Cin and an output terminal of rectifier bridge, and the other end is coupled between main power inductance Lm and the drain electrode of power switch pipe 110; Power switch pipe 110 source electrode is by peak point current sampling resistor Rcs ground connection.Newly-increased auxiliary winding L s one end is coupled between input capacitance Cin and an output terminal of rectifier bridge, and ground connection, resistance Rd and Ru is the divider resistance of auxiliary winding L s, one input end of the comparer 102 of common port Access Control chip 100 inside of resistance Rd and Ru, another input end of comparer 102 is input as 0V voltage.When the electric current in Lm arrives certain value, the voltage on Rcs exceedes internal reference voltage, and control chip 100 carrys out switch-off power switching tube 110 by the peak value comparison method unit 101 of inside, switching signal generating unit 104 and driver element 105; When in Lm during electric current vanishing, the common port voltage of Rd and Ru reduces to zero, comparer 102 exports demagnetization detection signal ZXC to logical circuit 103, control chip 100 opens power switch pipe 110 by switching signal generating unit 104 and driver element 105, thus the demagnetization realizing LED drive power detects.
Existing demagnetization testing circuit is in order to be detected pressure point, need increase auxiliary winding, two divider resistances, and control chip also wants many one to detect pin position, adds volume and the cost of whole LED drive power, is not suitable for the development trend of existing market LED small size, low cost.
Utility model content
The purpose of this utility model is, for the testing circuit Problems existing that demagnetizes in prior art, a kind of demagnetization detection control module and demagnetization detection system are provided, realize demagnetization by the drain voltage of the drain-gate capacitance coupled power switching tube of power switch pipe parasitism to detect, the cost overcoming tradition demagnetization detection mode is high, the technical matters of peripheral circuit complexity.
For achieving the above object, the utility model provides a kind of demagnetization detection control module, comprising: a peak value comparison method unit, a comparer, a logical circuit, a switching signal generating unit and a driver element; The input end of described peak value comparison method unit is the input end of described demagnetization detection control module, be coupled between the source electrode of the power switch pipe of LED switch power supply and an external peak current sampling unit, the output terminal electricity of described peak value comparison method unit is connected to described switching signal generating unit, described peak value comparison method unit, for when arriving a reference voltage when the voltage on described peak point current sampling unit, turns off described power switch pipe; The first input end electricity of described comparer is connected to the grid of described power switch pipe, second input end electricity of described comparer connects a reference voltage source, the output terminal electricity of described comparer connects described logical circuit, and described comparer is used for exporting demagnetization detection signal when the grid voltage of described power switch pipe is less than the voltage of described reference voltage source; Described logical circuit and described switching signal generating unit form loop; The input end of described driver element respectively electricity connects described switching signal generating unit and described logical circuit, the output terminal of described driver element is connected to the grid of described power switch pipe as the output terminal electricity of described demagnetization detection control module, and described demagnetization detection signal controls the turn-on instant of described power switch pipe by described logical circuit, switching signal generating unit and driver element; Wherein, after described power switch pipe turns off a lasting Preset Time, the grid being controlled described power switch pipe by described logical circuit and driver element becomes high-impedance state over the ground, and utilizes the stray capacitance of described power switch pipe to detect demagnetization signal.
For achieving the above object, the utility model additionally provides a kind of demagnetization detection system, comprise a main power inductance, a rectification unit, a power switch pipe and a peak point current sampling unit, the drain electrode electricity described main power inductance of connection and the rectification unit respectively of described power switch pipe, the source electrode electricity of described power switch pipe connects described peak point current sampling unit, and described demagnetization detection system comprises above-mentioned demagnetization detection control module further; Described demagnetization detection control module is coupled between the source electrode of described power switch pipe and described peak point current sampling unit by the input end of described peak value comparison method unit, is connected to the grid of described power switch pipe by the output terminal electricity of described driver element; Wherein, when the voltage on described peak point current sampling unit arrives a reference voltage, described demagnetization detection control module turns off described power switch pipe by described peak value comparison method unit, switching signal generating unit and driver element; After described power switch pipe turns off a lasting Preset Time, the grid that described demagnetization detection control module controls described power switch pipe by described logical circuit and driver element becomes high-impedance state over the ground, and utilizes the stray capacitance of described power switch pipe to detect demagnetization signal; When the grid voltage of described power switch pipe is less than described reference voltage source, described demagnetization detection control module exports demagnetization detection signal by described comparer, and described demagnetization detection signal controls the turn-on instant of described power switch pipe by described logical circuit, switching signal generating unit and driver element.
The utility model advantage is: realize demagnetization by the drain voltage of the drain-gate capacitance coupled power switching tube of power switch pipe parasitism and detect, and without the need to increasing auxiliary winding and detecting pin position, the cost of demagnetization detection mode is low, and peripheral circuit is simple.
Accompanying drawing explanation
Fig. 1, the realizing circuit figure that existing LED drive power demagnetization detects;
Fig. 2, the schematic diagram of demagnetization detection system one embodiment described in the utility model;
Fig. 3, the principle of work schematic diagram of driver element described in the utility model;
Fig. 4, realizing circuit figure described in an embodiment of driver element described in the utility model and clamping circuit;
Fig. 5, realizing circuit figure described in an embodiment of logical circuit described in the utility model;
Fig. 6, the working waveform figure of the circuit key point of demagnetization detection system described in the utility model.
Embodiment
The realizing circuit discovery that the utility model detects by analyzing the demagnetization of existing LED drive power, in the occasion of raster data model, when the electric current in main power inductance is reduced to zero, the drain voltage of power switch pipe can decline rapidly.Based on above-mentioned principle, the utility model realizes demagnetization by the drain voltage of the drain-gate capacitance coupled power switching tube of power switch pipe parasitism and detects.The demagnetization detection control module provided the utility model below in conjunction with accompanying drawing and demagnetization detection system elaborate.
With reference to figure 2, the schematic diagram of demagnetization detection system one embodiment described in the utility model, it is the voltage-dropping type Buck topology of raster data model conventional in LED switch power supply.Described demagnetization detection system comprises: a main power inductance Lm, a rectification unit, power switch pipe 210, peak point current sampling unit and a demagnetization detection control module 200.
In the present embodiment, described rectification unit adopts commutation diode D1, and in other embodiments, described rectification unit also can adopt other rectifier system to realize one-way conduction.In the present embodiment, described peak point current sampling unit adopts peak point current sampling resistor Rcs to obtain the source voltage terminal of power switch pipe; In other embodiments, described peak point current sampling unit also can adopt the source voltage terminal of other voltage sample mode to power switch pipe to sample.
Main power inductance Lm one end is coupled in an output terminal of the rectifier bridge that four diodes (D1-D4) form by Parallel opertation electric capacity Cout and pull-up resistor Rload; The main power inductance Lm other end is coupled in another output terminal of rectifier bridge by the commutation diode D1 of serial connection and input capacitance Cin.Input power S is connected to two input ends of rectifier bridge.The drain electrode of power switch pipe 210 respectively electricity connects one end of main power inductance Lm and the anode of commutation diode D1, and the source electrode of described power switch pipe 210 is by peak point current sampling resistor Rcs ground connection.
Described demagnetization detection control module 200 comprises: peak value comparison method unit 201, comparer 202, logical circuit 203, switching signal generating unit 204 and a driver element 205; Wherein, each assembly in described demagnetization detection control module 200 can be integrated on one piece of control chip and realize.
The input end of described peak value comparison method unit 201 is the input end of described demagnetization detection control module 200, be coupled between the source electrode of the power switch pipe 210 of LED switch power supply and peak point current sampling unit Rcs, the output terminal electricity of described peak value comparison method unit 201 is connected to described switching signal generating unit 204.Described peak value comparison method unit 201, for when arriving a reference voltage when the voltage on described peak point current sampling unit Rcs, turns off described power switch pipe 210.Described reference voltage can be control chip internal reference voltage.
The first input end electricity of described comparer 202 is connected to the grid of described power switch pipe 210, second input end electricity of described comparer 202 connects a reference voltage source Vb, the output terminal electricity of described comparer 202 connects described logical circuit 203, and described comparer 202 is for exporting demagnetization detection signal ZXC to described logical circuit 203 when the grid voltage of described power switch pipe 210 is less than the voltage of described reference voltage source Vb.
Described logical circuit 203 forms loop with described switching signal generating unit 204, thus be sent to described switching signal generating unit 204 by the demagnetization detection signal ZXC that described comparer 202 exports by described logical circuit 203, and receive the switch controlled signal Gate_ON of described switching signal generating unit 204 output.Described logical circuit 203 simultaneously electricity connects described driver element 205, described driver element 205 is exported to, to control power switch pipe 210 grid high-impedance state to generate control signal ON_HR according to the demagnetization detection signal ZXC of the described switch controlled signal Gate_ON of switching signal generating unit 204 output and the output of described comparer 202.
The input end of described driver element 205 respectively electricity connects described switching signal generating unit 204 and logical circuit 203, and the output terminal of described driver element 205 is connected to the grid of described power switch pipe 210 as the output terminal electricity of described demagnetization detection control module 200.Described demagnetization detection signal ZXC controls the turn-on instant of described power switch pipe 210 by described logical circuit 203, switching signal generating unit 204 and driver element 205.Wherein, after described power switch pipe 210 turns off a lasting preset time T b, the grid being controlled described power switch pipe 210 by described logical circuit 203 and driver element 205 becomes high-impedance state over the ground, and utilizes the stray capacitance of described power switch pipe 210 to detect demagnetization signal.
With reference to figure 3, the principle of work schematic diagram of driver element described in the utility model.Wherein, switch S 2 is connected in series low resistance resistor R1, and switch S 3 is connected in series high-impedance resistors R2.When Gate_ON signal is ' 1 ', switch S 1 conducting, switch S 2, S3 turn off, and the grid of power switch pipe 210 connects noble potential, power switch pipe 210 conducting; When Gate_ON signal is ' 0 ', switch S 1 turns off, switch S 2, S3 conducting, and power switch pipe 210 turns off; After Gate_ON signal became for ' 0 ' time delay a period of time (being designated as Tb), switch S 2 turns off, and now only has switch S 3 to be in conducting state, and because resistance R2 is high impedance, therefore the grid of power switch pipe 210 is high-impedance state, is demagnetization detected state.
In conjunction with reference to figure 2, Fig. 3, the principle of work of the demagnetization detection system described in present embodiment is specially: when described power switch pipe 210 conducting, the electric current of described main power inductance Lm starts to rise linearly over time, the drain current of power switch pipe 210 rises linearly over time, therefore the voltage on peak point current sampling resistor Rcs also rises linearly over time.When the voltage on peak point current sampling resistor Rcs arrives chip internal reference voltage, described demagnetization detection control module 200 is by described peak value comparison method unit 201, switching signal generating unit 204 and driver element 205 switch-off power switching tube 210; Now described commutation diode D1 conducting, the electric current of main power inductance Lm starts to decline linearly over time; Now the grid of power switch pipe 210 is low resistance over the ground, strong cohesiveness ground.After continuing for some time (being designated as Tb), demagnetization detection control module 200 is by logical circuit 203, and the effect of driver element 205 makes the grid of power switch pipe 210 become high-impedance state over the ground, weak ground connection, is demagnetization detected state.When the electric current of main power inductance Lm continues to reduce, and when reducing to zero, the drain voltage of power switch pipe 210 starts to decline; Because its grid resistance state is high-impedance state, by the coupling of stray capacitance Cgd between the drain electrode of power switch pipe 210 and grid level, its grid voltage starts decline with drain voltage and decline.When the grid voltage of power switch pipe 210 drops to the voltage of reference voltage source Vb, comparer 202 exports demagnetization signal ZXC, and now the grid of power switch pipe 210 becomes low resistance state over the ground; Demagnetization signal ZXC, by logical circuit 203, switching signal generating unit 204 and driver element 205, controls the turn-on instant of described power switch pipe 210.When Gate_ON signal in Fig. 2 is ' 1 ', represent power switch pipe 210 conducting, when Gate_ON signal is ' 0 ', represents power switch pipe 210 and turn off.
Continue with reference to figure 2, as preferred embodiment, demagnetization detection control module 200 described in the utility model comprises a clamping circuit 206 further, the input end electricity of described clamping circuit 206 is connected to described switching signal generating unit 204, the output terminal electricity of described clamping circuit 206 is connected to the grid of described power switch pipe 210, described clamping circuit 206 for prevent described power switch pipe 210 from turning off and grid over the ground for high-impedance state time misleading.
With reference to figure 4, realizing circuit figure described in an embodiment of driver element described in the utility model and clamping circuit.In the present embodiment, described driver element 205 comprises further: rejection gate 42, a 1 first NMOS tube MN1, level displacement circuit 44 and a PMOS MP1.Two input ends of described rejection gate 42 are connected to described switching signal generating unit 204 and described logical circuit 203 respectively by a phase inverter (as shown in Figure 4 41,43) electricity, and the output terminal of described rejection gate 42 is connected to the grid of described first NMOS tube MN1 by phase inverter 45 electricity.The source ground of described first NMOS tube MN1, drain electrode electricity is connected to the grid of described power switch pipe 210.The input end of described level displacement circuit 44 respectively electricity is connected to described switching signal generating unit 204 and power voltage terminal (as shown in Figure 4 VDD, VCC), and the output terminal of described level displacement circuit 44 is connected to the grid of described PMOS MP1 by phase inverter 47 electricity; Level displacement circuit effect is that the logical signal of low-voltage is converted to high-tension logical signal.The source electrode electricity of described PMOS MP1 is connected to power voltage terminal (as shown in Figure 4 VCC), and the drain electrode of described PMOS MP1 is to the grid of described power switch pipe 210.In the present embodiment, described clamping circuit 206 comprises one second NMOS tube MN2 further, and the grid of described second NMOS tube MN2 is the input end of described clamping circuit 206, and the drain electrode of described second NMOS tube MN2 is the output terminal of described clamping circuit 206; The source electrode of described second NMOS tube MN2 is by a clamp diode D2 ground connection, the grid of described second NMOS tube MN2 is connected to described switching signal generating unit 204 by phase inverter 43 electricity, and the drain electrode electricity of described second NMOS tube MN2 is connected to the grid of described power switch pipe 210.
The implementation of described driver element and clamping circuit is provided below in conjunction with Fig. 4, wherein Gate_ON signal is the switch controlled signal that switching signal generating unit 204 exports, DRAIN signal represents the drain voltage of power switch pipe 210, GATE signal represents the grid voltage of power switch pipe 210, and ON_HR is the power switch pipe 210 grid high-impedance state control signal that logical circuit 203 exports.When Gate_ON is ' 0 ', the second NMOS tube MN2 conducting of described clamping circuit 206.When ON_HR is ' 1 ' or Gate_ON is ' 1 ', the first NMOS tube MN1 of described driver element 205 turns off.When Gate_ON is ' 0 ', the PMOS MP1 of described driver element 205 turns off; Now, if ON_HR is also ' 0 ', then the first NMOS tube MN1 conducting, the grid (GATE end) of power switch pipe 210 is low resistance state over the ground, and also namely power switch pipe 210 is strong off state; If ON_HR is ' 1 ', then the first NMOS tube MN1 turns off, and now only have the second NMOS tube MN2 conducting, power switch pipe 210 is weak off state.
With reference to figure 5, realizing circuit figure described in an embodiment of logical circuit described in the utility model.In the present embodiment, described logical circuit 203 comprises further: negative edge delay unit 51, rest-set flip-flop, a rejection gate 52.The input end electricity of described negative edge delay unit 51 is connected to described switching signal generating unit 204, and output terminal electricity is connected to an input end of described rejection gate 52.One input end electricity of described rest-set flip-flop is connected to described switching signal generating unit 204, another input end electricity of described rest-set flip-flop is connected to the output terminal of described comparer 202, another input end of rejection gate 52 described in the output termination of described rest-set flip-flop; Wherein, described rest-set flip-flop is made up of two rejection gates 53,54.The output terminal electricity of described rejection gate 52 is connected to described driver element 205.Wherein, the input signal of shown logical circuit 203 is the demagnetization detection signal ZXC of the switch controlled signal Gate_ON of switching signal generating unit 204 output, the output of described comparer 202, outputs signal as power switch pipe 210 grid high-impedance state control signal ON_HR.
With reference to figure 6, the working waveform figure of the circuit key point of demagnetization detection system described in the utility model, wherein, Gate_ON signal is the switch controlled signal that switching signal generating unit 204 exports, DRAIN signal represents the drain voltage of power switch pipe 210, GATE signal represents the grid voltage of power switch pipe 210, and ON_HR is the power switch pipe 210 grid high-impedance state control signal that logical circuit 203 exports, and ZXC signal is the demagnetization detection signal that comparer 202 exports.When Gate_ON signal is ' 1 ', power switch pipe 210 conducting, DRAIN signal is low level; When Gate_ON signal is ' 0 ', power switch pipe 210 turns off, and DRAIN signal becomes high level; After Tb time delay after a while, power switch pipe 210 becomes weak off state from strong off state, enters demagnetization detected state.After demagnetization terminates, power switch pipe 210 drain voltage starts to decline, and the grid G ATE signal of power switch pipe 210 is by voltage couples drain D RAIN signal; When GATE signal is lower than certain level Vb, comparer 202 exports ZXC signal, and power switch pipe 210 becomes strong off state from weak off state.Also namely, the utility model realizes demagnetization by the drain voltage of the drain-gate capacitance coupled power switching tube 210 of power switch pipe 210 parasitism and detects, and without the need to increasing auxiliary winding, the cost of demagnetization detection mode is low, and peripheral circuit is simple.
The above is only preferred implementation of the present utility model; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the utility model principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection domain of the present utility model.
Claims (10)
1. a demagnetization detection control module, is characterized in that, comprising: a peak value comparison method unit, a comparer, a logical circuit, a switching signal generating unit and a driver element;
The input end of described peak value comparison method unit is the input end of described demagnetization detection control module, be coupled between the source electrode of the power switch pipe of LED switch power supply and an external peak current sampling unit, the output terminal electricity of described peak value comparison method unit is connected to described switching signal generating unit, described peak value comparison method unit, for when arriving a reference voltage when the voltage on described peak point current sampling unit, turns off described power switch pipe;
The first input end electricity of described comparer is connected to the grid of described power switch pipe, second input end electricity of described comparer connects a reference voltage source, the output terminal electricity of described comparer connects described logical circuit, and described comparer is used for exporting demagnetization detection signal when the grid voltage of described power switch pipe is less than the voltage of described reference voltage source;
Described logical circuit and described switching signal generating unit form loop;
The input end of described driver element respectively electricity connects described switching signal generating unit and described logical circuit, the output terminal of described driver element is connected to the grid of described power switch pipe as the output terminal electricity of described demagnetization detection control module, and described demagnetization detection signal controls the turn-on instant of described power switch pipe by described logical circuit, switching signal generating unit and driver element;
Wherein, after described power switch pipe turns off a lasting Preset Time, the grid being controlled described power switch pipe by described logical circuit and driver element becomes high-impedance state over the ground, and utilizes the stray capacitance of described power switch pipe to detect demagnetization signal.
2. demagnetization detection control module according to claim 1, it is characterized in that, described driver element comprises further: a rejection gate, one first NMOS tube, a level displacement circuit and a PMOS; Two input ends of described rejection gate are connected to described switching signal generating unit and described logical circuit respectively by a phase inverter electricity, and the output terminal of described rejection gate is connected to the grid of described first NMOS tube by a phase inverter electricity; The source ground of described first NMOS tube, drain electrode electricity is connected to the grid of described power switch pipe; The input end of described level displacement circuit respectively electricity is connected to described switching signal generating unit and power voltage terminal, and the output terminal of described level displacement circuit is connected to the grid of described PMOS by a phase inverter electricity; The source electrode electricity of described PMOS is connected to power voltage terminal, and the drain electrode of described PMOS is to the grid of described power switch pipe.
3. demagnetization detection control module according to claim 1, it is characterized in that, described logical circuit comprises further: a negative edge delay unit, a rest-set flip-flop, a rejection gate; The input end electricity of described negative edge delay unit is connected to described switching signal generating unit, and output terminal electricity is connected to an input end of described rejection gate; One input end electricity of described rest-set flip-flop is connected to described switching signal generating unit, and another input end electricity of described rest-set flip-flop is connected to the output terminal of described comparer, another input end of rejection gate described in the output termination of described rest-set flip-flop; The output terminal electricity of described rejection gate is connected to described driver element.
4. demagnetization detection control module according to claim 1, it is characterized in that, described demagnetization detection control module comprises a clamping circuit further, the input end electricity of described clamping circuit is connected to described switching signal generating unit, the output terminal electricity of described clamping circuit is connected to the grid of described power switch pipe, described clamping circuit for prevent described power switch pipe turn off and grid over the ground for high-impedance state time misleading.
5. demagnetization detection control module according to claim 4, it is characterized in that, described clamping circuit comprises one second NMOS tube further, and the grid of described second NMOS tube is the input end of described clamping circuit, and the drain electrode of described second NMOS tube is the output terminal of described clamping circuit; The source electrode of described second NMOS tube is by a clamp diode ground connection, and the grid of described second NMOS tube is connected to described switching signal generating unit by a phase inverter electricity, and the drain electrode electricity of described second NMOS tube is connected to the grid of described power switch pipe.
6. a demagnetization detection system, comprise a main power inductance, a rectification unit, a power switch pipe and a peak point current sampling unit, the drain electrode electricity described main power inductance of connection and the described rectification unit respectively of described power switch pipe, the source electrode electricity of described power switch pipe connects described peak point current sampling unit, it is characterized in that, comprise demagnetization detection control module according to claim 1 further;
Described demagnetization detection control module is coupled between the source electrode of described power switch pipe and described peak point current sampling unit by the input end of described peak value comparison method unit, is connected to the grid of described power switch pipe by the output terminal electricity of described driver element;
Wherein, when the voltage on described peak point current sampling unit arrives a reference voltage, described demagnetization detection control module turns off described power switch pipe by described peak value comparison method unit, switching signal generating unit and driver element; After described power switch pipe turns off a lasting Preset Time, the grid that described demagnetization detection control module controls described power switch pipe by described logical circuit and driver element becomes high-impedance state over the ground, and utilizes the stray capacitance of described power switch pipe to detect demagnetization signal; When the grid voltage of described power switch pipe is less than described reference voltage source, described demagnetization detection control module exports demagnetization detection signal by described comparer, and described demagnetization detection signal controls the turn-on instant of described power switch pipe by described logical circuit, switching signal generating unit and driver element.
7. demagnetization detection system according to claim 6, is characterized in that, described driver element comprises further: a rejection gate, one first NMOS tube, a level displacement circuit and a PMOS; Two input ends of described rejection gate are connected to described switching signal generating unit and described logical circuit respectively by a phase inverter electricity, and the output terminal of described rejection gate is connected to the grid of described first NMOS tube by a phase inverter electricity; The source ground of described first NMOS tube, drain electrode electricity is connected to the grid of described power switch pipe; The input end of described level displacement circuit respectively electricity is connected to described switching signal generating unit and power voltage terminal, and the output terminal of described level displacement circuit is connected to the grid of described PMOS by a phase inverter electricity; The source electrode electricity of described PMOS is connected to power voltage terminal, and the drain electrode of described PMOS is to the grid of described power switch pipe.
8. demagnetization detection system according to claim 6, is characterized in that, described logical circuit comprises further: a negative edge delay unit, a rest-set flip-flop, a rejection gate; The input end electricity of described negative edge delay unit is connected to described switching signal generating unit, and output terminal electricity is connected to an input end of described rejection gate; One input end electricity of described rest-set flip-flop is connected to described switching signal generating unit, and another input end electricity of described rest-set flip-flop is connected to the output terminal of described comparer, another input end of rejection gate described in the output termination of described rest-set flip-flop; The output terminal electricity of described rejection gate is connected to described driver element.
9. demagnetization detection system according to claim 6, it is characterized in that, described demagnetization detection control module comprises a clamping circuit further, the input end electricity of described clamping circuit is connected to described switching signal generating unit, the output terminal electricity of described clamping circuit is connected to the grid of described power switch pipe, described clamping circuit for prevent described power switch pipe turn off and grid over the ground for high-impedance state time misleading.
10. demagnetization detection system according to claim 9, it is characterized in that, described clamping circuit comprises one second NMOS tube further, and the grid of described second NMOS tube is the input end of described clamping circuit, and the drain electrode of described second NMOS tube is the output terminal of described clamping circuit; The source electrode of described second NMOS tube is by a clamp diode ground connection, and the grid of described second NMOS tube is connected to described switching signal generating unit by a phase inverter electricity, and the drain electrode electricity of described second NMOS tube is connected to the grid of described power switch pipe.
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| CN104166107A (en) * | 2014-08-18 | 2014-11-26 | 上海晶丰明源半导体有限公司 | Demagnetization detecting control module and demagnetization detecting system |
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| CN104166107A (en) * | 2014-08-18 | 2014-11-26 | 上海晶丰明源半导体有限公司 | Demagnetization detecting control module and demagnetization detecting system |
| CN107968567A (en) * | 2017-12-20 | 2018-04-27 | 上海艾为电子技术股份有限公司 | A kind of nmos switch tube drive circuit |
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