CN103887770A - Overvoltage protective circuit in LED driving power supply without auxiliary winding - Google Patents
Overvoltage protective circuit in LED driving power supply without auxiliary winding Download PDFInfo
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Abstract
The invention provides an overvoltage protective circuit in an LED driving power supply without an auxiliary winding. A sampling and holding unit detects a voltage Vcs flowing through a current sampling resistor of the driving power supply; a time detection unit detects conduction time of a secondary side diode of the driving power supply, and the conduction time is utilized to generate a voltage Vref via a current source and a charging capacitor; when the conduction time of the secondary side diode ends, a first comparator compares the voltage Vref and the voltage Vcs, and when the voltage Vref is less than the voltage Vcs, the first comparator outputs an overvoltage signal to a control logic unit; the control logic unit outputs a switching signal to a switching driving unit according to the overvoltage signal; and the switching driving unit turns off a power tube of the driving power supply according to the received switching signal. An independent transformer winding is not needed in detection of the output voltage, and detection of a pin bit is also not needed so that the manufactured LED driving power supply is smaller in volume and lower in cost.
Description
Technical field
The present invention relates to LED over-voltage protection technology field, in particular, relate to a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding.
Background technology
Along with the development of electronic technology, the range of application of LED lamp is also more and more wider.The operation principle of LED lamp is to provide constant output current that LED lamp is lighted by LED driving power.Therefore, in the situation that output LED open circuit or other situation uprise output voltage, LED driving power must take appropriate measures, and allows output voltage be no more than the withstand voltage of output capacitance, otherwise output capacitance is just easily burned.In traditional LED driving power, generally adopt an independent Transformer Winding to detect output voltage, then, by electric resistance partial pressure, be input to the independent pin position of chip and carry out direct-detection output voltage, thereby judge whether driving power overvoltage occurs.
As shown in Figure 1, be the circuit theory diagrams of overvoltage protection part in LED driving power in prior art.What Fig. 1 was given is a kind of typical application drawing of voltage-dropping type Buck circuit.Generally include: rectifier bridge 101, input filter capacitor 102, output capacitance 103, the former limit of voltage device winding 104, transformer is assisted winding 110, rectifier diode 105, power supply electric capacity 109, LED load 113, switching power tube 107, current sampling resistor 108, divider resistance 111, divider resistance 112, control chip 120.In the time of switching power tube 107 conducting, transformer primary side 104 Current rises, the electric current sampling resistor 108 of flowing through produces voltage signal, when current reference voltage in this voltage signal reaches chip 110, switching power tube 107 turn-offs, the electric current of winding 104 the insides, former limit is by rectifying tube 105 afterflows, and in the time that chip 120 detects that electric current in rectifying tube 105 is zero, switching power tube 107 is opened.In the time that switching power tube 107 turn-offs, the output voltage that the voltage difference on former limit winding 104 is LED, now on auxiliary winding 110, the voltage of induction is also the proportional relation of output voltage, the turn ratio that proportionality coefficient is winding.If now LED open circuit, output voltage uprises, if FB voltage higher than the internal reference of chip, chip 120 decision-making systems enter overvoltage condition, realize defencive function.
This shows; volume and the cost of the whole driving power of LED in traditional LED overvoltage protection scheme, are increased; in order to detect pressure point; need to increase a Transformer Winding; two divider resistances; and chip also wants many one to detect pin positions, be not suitable for existing market LED small size, development trend cheaply.
Summary of the invention
In view of this; the invention provides a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding; do not need independent Transformer Winding to detect output voltage, do not need to detect pin position yet, can make the volume of the LED driving power of making less, cost is lower.
For achieving the above object, the invention provides following technical scheme: a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding, be applied to LED driving power, comprise: sample holding unit, current source, charging capacitor, the first comparator, control logic unit, switch drive unit and time detecting unit; Wherein:
Described sample holding unit detects the voltage Vcs on the current sampling resistor that flows through described LED driving power;
The ON time of the secondary diode of LED driving power described in described time detecting unit inspection, and utilize described ON time to produce a voltage Vref by described current source and charging capacitor;
In the time that the described secondary diode current flow time finishes, the more described voltage Vref of described the first comparator and described voltage Vcs, in the time that described voltage Vref is less than described voltage Vcs, described the first comparator output overvoltage signal is to described control logic unit;
Described control logic unit is according to extremely described switch drive unit of the described overvoltage signal output switch signal receiving;
Described switch drive unit turn-offs the power tube of described LED driving power according to the described switching signal receiving.
Preferably, the input of described sample holding unit is connected with the current sampling resistor of described LED driving power, and output is connected with the electrode input end of described the first comparator;
The negative input of described the first comparator is connected with described charging capacitor and described current source, and the output of described the first comparator is connected with the input of described control logic unit;
The output of described control logic unit is connected with the input of described switch drive unit;
The output of described switch drive unit is connected with the grid of the first power switch pipe of described LED driving power;
The input of described time detecting unit is connected with the drain electrode of the first power switch pipe of described LED driving power, and the output of described time detecting unit is connected with described charging capacitor and described current source.
Preferably, described LED driving power also comprises the second power switch pipe, and described time detecting unit comprises: the first electric capacity, current detection circuit, electric current turn potential circuit and the second comparator;
The first end of described the first electric capacity is connected with the grid of the second power switch pipe of described LED driving power, and in the time that the grid voltage of described the second power switch pipe declines, described the first capacitor discharge, produces the first electric current;
The input of described current detection circuit is connected with the second end of described the first electric capacity, detects described the first electric current;
Described electric current turns the input of potential circuit and the output of described current detection circuit is connected, and described the first electric current is converted into described the first voltage V0;
The in-phase input end of described the second comparator meets described predeterminated voltage V1, the inverting input of described the second comparator is connected with the output that described electric current turns potential circuit, for the size of more described the first voltage V0 and described voltage V1, produce described secondary diode current crossover point signal.
Preferably, described current detection circuit comprises: the first metal-oxide-semiconductor, the 3rd metal-oxide-semiconductor and the second electric capacity;
The source electrode of described the first metal-oxide-semiconductor connects external voltage, the grid of described the first metal-oxide-semiconductor is as the output of described current detection circuit, the drain electrode of described the first metal-oxide-semiconductor is connected with the first end of described the second electric capacity and the grid of described the first metal-oxide-semiconductor respectively, the second end of described the second electric capacity is connected with the source electrode of described the second metal-oxide-semiconductor, the drain electrode of described the second metal-oxide-semiconductor is as the input of described current detection circuit, and the grid of described the second metal-oxide-semiconductor connects bias voltage.
Preferably, described electric current turns potential circuit and comprises: the second metal-oxide-semiconductor, the 3rd electric capacity and the first resistance;
The source electrode of described the second metal-oxide-semiconductor connects external voltage, the grid of described the second metal-oxide-semiconductor turns the input of potential circuit as described electric current, the drain electrode of described the second metal-oxide-semiconductor is connected with the first end of described the 3rd electric capacity and the first end of described the first resistance respectively, and turn the output of potential circuit as described electric current, the equal ground connection of the second end of the second end of described the 3rd electric capacity and described the first resistance.
Preferably, described predeterminated voltage V1 is the reference voltage that reference voltage source produces.
Provided by the present invention a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding, detect the voltage on the current sampling resistor that flows through LED driving power by sample holding unit, and the ON time of secondary diode by time detecting unit inspection LED driving power, and utilize ON time to produce a voltage by current source and charging capacitor, by relatively two voltages of the first comparator, in the time that the voltage on current sampling resistor is greater than secondary diode current flow, produce voltage time, the first comparator output overvoltage signal is to control logic unit, the overvoltage signal output switch signal that control logic unit basis receives is to switch drive unit, switch drive unit turn-offs the first power switch pipe of LED driving power according to the switching signal receiving, thereby realize overvoltage protection.This shows, the present invention does not compared with prior art need independent Transformer Winding to detect output voltage, does not need to detect pin position yet, can make the volume of the LED driving power of making less, cost is lower.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skills, do not paying under the prerequisite of creative work, other accompanying drawing can also be provided according to the accompanying drawing providing.
Fig. 1 is LED driving power circuit schematic diagram in prior art;
Fig. 2 is a kind of schematic diagram without the overvoltage crowbar in the LED driving power of auxiliary winding disclosed by the invention;
Fig. 3 is the schematic diagram of another kind disclosed by the invention without the overvoltage crowbar in the LED driving power of auxiliary winding;
Fig. 4 is the structural representation of time detecting disclosed by the invention unit;
Fig. 5 is the structural representation of the current detection circuit in time detecting disclosed by the invention unit;
Fig. 6 is the structural representation that the electric current in time detecting disclosed by the invention unit turns potential circuit;
Fig. 7 is a kind of voltage waveform view without over-voltage protection point in the overvoltage crowbar in the LED driving power of auxiliary winding disclosed by the invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only a part of embodiment of the present invention, rather than whole embodiment.Based on the embodiment in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.
The embodiment of the invention discloses a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding; do not need independent Transformer Winding to detect output voltage; do not need to detect pin position, just can make the volume of the LED driving power of making less, cost is lower yet.
High in order to solve in prior art cost, apply limited problem, the invention provides a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding.Circuit provided by the invention has saved auxiliary winding 110 of the prior art, divider resistance 111 and divider resistance 112, and saved the FB pin of chip 120.And in the application that can change at peak current, detect whether overvoltage of output voltage, thereby reach low cost, the target that reliability is strong.
As shown in Figure 2, for disclosed by the invention a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding.Wherein, LED driving power comprises: rectifier bridge 201, filter inductance 202, electric capacity of voltage regulation 203, transformer 204, transformer secondary diode 205, output capacitance 206, outputting inductance 207, the first power switch pipe 208, current sampling resistor 209.Overvoltage crowbar comprises: sample holding unit 210, current source 211, charging capacitor 212, the first comparator 213, control logic unit 214, switch drive unit 215 and time detecting unit 216.Wherein:
The output of rectifier bridge 201 is connected with the input of filter inductance 202, the output of filter inductance 202 is connected with the input of electric capacity of voltage regulation 203 and the former limit winding of transformer 204, the output head grounding of electric capacity of voltage regulation 203, transformer secondary diode 205 is connected with the secondary of transformer 204, and output capacitance 206 and outputting inductance 207 are connected in parallel on respectively on the secondary winding of transformer 204.The drain electrode of the first power tube 208 is connected with the former limit of transformer 204, and source electrode is connected with the input of current sampling resistor 209, the output head grounding of current sampling resistor 209.
The input of sample holding unit 210 is connected with the input of current sampling resistor 209, and output is connected with the electrode input end of comparator 213; The negative input of comparator 213 is connected with charging capacitor 212 and current source 211, and the output of comparator 213 is connected with the input of control logic unit 214;
The output of control logic unit 214 is connected with the input of described switch drive unit 215; The output of switch drive unit 215 is connected with the grid of the first power switch pipe 208; The input of time detecting unit 216 is connected with the drain electrode of the first power switch pipe 208, and the output of time detecting unit 216 is connected with charging capacitor 212 and current source 211.
The course of work of above-mentioned overvoltage crowbar and principle are: sample holding unit 210 detects the voltage Vcs on current flowing sampling resistor 209, and the peak value sampling of Vcs is out saved as to Vcspeak.Time detecting unit 216 detects the ON time Tons of transformer secondary diode 205, the time T ons that utilization detects produces a voltage Vref by current source 211 and charging capacitor 212, detect that transformer secondary diode 205 ON time Tons finish time, the voltage Vcspeak that the voltage Vref of generation and sample holding unit 210 are detected compares in comparator 213, if Vref<Vcspeak, comparator 213 output overvoltage signal OVP are to control logic unit 214, control logic unit 214 output switching signals are to switch drive unit 215, driver element 215 turn-offs the first power switch pipe 208 according to the switching signal receiving, thereby realize the overvoltage protection to LED.
As shown in Figure 3, for disclosed by the invention a kind of without the overvoltage crowbar in the LED driving power of auxiliary winding.Wherein, LED driving power comprises: rectifier bridge 301, filter inductance 302, electric capacity of voltage regulation 303, supplying resistance 304, power supply electric capacity 305, transformer 306, transformer secondary diode 307, output capacitance 308, outputting inductance 309, the first power switch pipe 310, diode 311, the second power switch pipe 312, current sampling resistor 313.Overvoltage crowbar comprises: sample holding unit 314, current source 315, charging capacitor 316, the first comparator 317, control logic unit 318, switch drive unit 319 and time detecting unit 320.Wherein:
The output of rectifier bridge 301 is connected with the input of filter inductance 302, the output of filter inductance 302 is connected with input, the input of supplying resistance 304 and the former limit winding of transformer 306 of electric capacity of voltage regulation 303 respectively, the output head grounding of electric capacity of voltage regulation 303, the output of supplying resistance 304 is connected with input and the power supply VCC of power supply electric capacity 305 respectively, the output head grounding of power supply electric capacity 305.Transformer secondary diode 307 is connected with the secondary of transformer 306, and output capacitance 308 and outputting inductance 309 are connected in parallel on respectively on the secondary winding of transformer 306.The grid of the second power switch pipe 312 is connected with power supply, and drain electrode is connected with the former limit winding of transformer 306, and source electrode is connected with the anode of diode 311 and the drain electrode of the first power tube 310.The negative electrode of diode 311 is connected with power supply VCC, and the source electrode of the first power tube 310 is connected with the input of current sampling resistor 313, the output head grounding of current sampling resistor 313.
The input of sample holding unit 314 is connected with the input of current sampling resistor 313, and output is connected with the electrode input end of the first comparator 317; The negative input of the first comparator 317 is connected with charging capacitor 316 and current source 315, and the output of the first comparator 317 is connected with the input of control logic unit 318;
The output of control logic unit 318 is connected with the input of described switch drive unit 319; The output of switch drive unit 319 is connected with the grid of the first power switch pipe 310; The input of time detecting unit 320 is connected with the anode of diode 311 and the source electrode of the second power switch pipe 310, and the output of time detecting unit 320 is connected with charging capacitor 316 and current source 315.
The course of work of above-mentioned overvoltage crowbar and principle are: sample holding unit 314 detects the voltage Vcs on current flowing sampling resistor 313, and the peak value sampling of Vcs is out saved as to Vcspeak.Time detecting unit 320 detects the ON time Tons of transformer secondary diode 307, the time T ons that utilization detects produces a voltage Vref by current source 215 and charging capacitor 216, detect that transformer secondary diode 307 ON time Tons finish time, the voltage Vcspeak that the voltage Vref of generation and sample holding unit 314 are detected compares in the first comparator 317, if Vref<Vcspeak, the first comparator 317 output overvoltage signal OVP are to control logic unit 318, control logic unit 318 output switching signals are to switch drive unit 319, driver element 319 turn-offs the second power switch pipe 310 according to the switching signal receiving, thereby realize the overvoltage protection to LED.
Above-mentioned voltage Vref can use following formulae express:
V
ref=K×I
ref×T
ons/C
ref
Wherein, K is the intrinsic coefficient of time detecting unit chip internal, and Iref is current source size, and Tons is the secondary diode current flow time, and Cref is charging capacitor.
Above-mentioned voltage Vcspeak can use following formulae express:
V
cspeak=V
out×N×T
ons×R
cs/L
m
Wherein Lm is the inductance electric weight of transformer primary side coil, and Vout is the size of transformer output voltage, and Rcs is the resistance that circuit adopts sampling resistor, and N is transformer primary side secondary turn ratio.
In the time of Vcs>Vref, think that output voltage is too high, there is OVP protection, over-voltage protection point is
Over-voltage protection point can be by peripheral setting parameter as can be seen from the above equation.
Concrete, as shown in Figure 4, time detecting unit comprises: the first capacitor C 4, current detection circuit 401, electric current turn potential circuit 402 and the second comparator 403.
Its circuit connecting relation is:
The first end of the first capacitor C 4 is connected with the source electrode of the second power tube 310 of LED driving power in Fig. 3, and in the time that the source voltage of the second power tube 310 declines, the first capacitor C 4 is discharged, and produces the first electric current;
The input of current detection circuit 410 is connected with the second end of the first capacitor C 4, detects described the first electric current;
The input that electric current turns potential circuit 402 is connected with the output of current detection circuit 401, and described the first electric current is converted into described the first voltage V0;
The in-phase input end of the second comparator 403 meets described predeterminated voltage V1, the inverting input of the second comparator 403 is connected with the output that electric current turns potential circuit 402, for the size of more described the first voltage V0 and described voltage V1, produce described secondary diode current crossover point signal.
Here it should be noted that, current detection circuit 401 and electric current turn potential circuit 402 realize circuit have a variety of, in the present embodiment, not particularize.Those skilled in the art are inwardly of the present invention, within current detection circuit and electric current being turned to the selecting and all belong to protection scope of the present invention of different structure of potential circuit.
Preferably, the invention provides a kind of concrete current detection circuit, as shown in Figure 5, comprising: the first metal-oxide-semiconductor P1, the 3rd metal-oxide-semiconductor P3 and the second capacitor C C1.
The annexation of each device is:
The source electrode of the first metal-oxide-semiconductor connects external voltage, the grid of the first metal-oxide-semiconductor is as the output of current detection circuit, the drain electrode of the first metal-oxide-semiconductor is connected with the first end of the second electric capacity and the grid of the first metal-oxide-semiconductor respectively, the second end of the second electric capacity is connected with the source electrode of the second metal-oxide-semiconductor, the drain electrode of the second metal-oxide-semiconductor is as the input of current detection circuit, and the grid of the second metal-oxide-semiconductor connects bias voltage.
Its current detecting principle is: in the time that input Iin has electric current outwards to flow out, this electric current can be detected by the first metal-oxide-semiconductor P1, realize the effect of current detecting.It should be noted that, wherein, Vb is the built-in bias voltage of drive circuit.
Same, the present invention also provides a kind of concrete electric current to turn potential circuit, as shown in Figure 6, comprising: the second metal-oxide-semiconductor P2, the 3rd capacitor C C2 and the first resistance R R1.
This electric current turns in potential circuit, and the annexation of each device is as follows:
The source electrode of the second metal-oxide-semiconductor connects external voltage, the grid of the second metal-oxide-semiconductor turns the input of potential circuit as electric current, the drain electrode of the second metal-oxide-semiconductor is connected with the first end of the 3rd electric capacity and the first end of the first resistance respectively, and turn the output of potential circuit as electric current, the equal ground connection of the second end of the second end of the 3rd electric capacity and the first resistance.
The operation principle that its electric current turns voltage is: the electric current being detected by the first metal-oxide-semiconductor flow into the 3rd capacitor C C2 and the first resistance R R1 by the second metal-oxide-semiconductor P2, after the filtering of the 3rd capacitor C C2 and the first resistance R R1 is processed, is converted into the first voltage V0.
Afterwards this first voltage V0 and predeterminated voltage V1 are compared, the second comparator 303 produces a secondary diode current crossover point signal.
It should be noted that, predeterminated voltage V1 in above-mentioned time detecting unit can be the reference voltage that the reference voltage source of drive circuit inside produces, also can be the reference voltage being produced by external voltage source, the production process of predeterminated voltage not limited in the present embodiment.
Visible, time detecting provided by the invention unit, can realize the current over-zero dot information that detects secondary diode, does not need again to adopt independent transformer to assist winding, and it is little that its circuit takies volume, and cost is low.
As shown in Figure 7, be the oscillogram of overvoltage crowbar over-voltage protection point disclosed by the invention.Concrete, when Gate_on is high level, the first power switch pipe conducting, its linear rising of source voltage Vcs, when Gate_on becomes low level time, conducting finishes, the maximum of Vcs is Vcspeak, the secondary diode current flow time starts (Tons is for high) simultaneously, Vref starts linear rising, in the time that secondary diode current flow time T ons finishes (Tons is low), Vref stops rising, by Vref now with sample before and the Vcspeak that maintains compares, if Vref is now less than Vcspeak, output over-voltage protection signal OVP.Chip enters overvoltage protection state.
In this specification, each embodiment adopts the mode of going forward one by one to describe, and what each embodiment stressed is and the difference of other embodiment, between each embodiment identical similar part mutually referring to.For the device providing for embodiment, because its method providing with embodiment is corresponding, so description is fairly simple, relevant part illustrates referring to method part.
To the above-mentioned explanation of provided embodiment, make professional and technical personnel in the field can realize or use the present invention.To be apparent for those skilled in the art to the multiple modification of these embodiment, General Principle as defined herein can, in the situation that not departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle provided in this article and features of novelty.
Claims (6)
1. one kind without the overvoltage crowbar in the LED driving power of auxiliary winding, be applied to LED driving power, it is characterized in that, comprising: sample holding unit, current source, charging capacitor, the first comparator, control logic unit, switch drive unit and time detecting unit; Wherein:
Described sample holding unit detects the voltage Vcs on the current sampling resistor that flows through described LED driving power;
The ON time of the secondary diode of LED driving power described in described time detecting unit inspection, and utilize described ON time to produce a voltage Vref by described current source and charging capacitor;
In the time that the described secondary diode current flow time finishes, the more described voltage Vref of described the first comparator and described voltage Vcs, in the time that described voltage Vref is less than described voltage Vcs, described the first comparator output overvoltage signal is to described control logic unit;
Described control logic unit is according to extremely described switch drive unit of the described overvoltage signal output switch signal receiving;
Described switch drive unit turn-offs the power tube of described LED driving power according to the described switching signal receiving.
2. overvoltage crowbar according to claim 1, is characterized in that, the input of described sample holding unit is connected with the current sampling resistor of described LED driving power, and output is connected with the electrode input end of described the first comparator;
The negative input of described the first comparator is connected with described charging capacitor and described current source, and the output of described the first comparator is connected with the input of described control logic unit;
The output of described control logic unit is connected with the input of described switch drive unit;
The output of described switch drive unit is connected with the grid of the first power switch pipe of described LED driving power;
The input of described time detecting unit is connected with the drain electrode of the first power switch pipe of described LED driving power, and the output of described time detecting unit is connected with described charging capacitor and described current source.
3. overvoltage crowbar according to claim 1 and 2, it is characterized in that, described LED driving power also comprises the second power switch pipe, and described time detecting unit comprises: the first electric capacity, current detection circuit, electric current turn potential circuit and the second comparator;
The first end of described the first electric capacity is connected with the grid of the second power switch pipe of described LED driving power, and in the time that the grid voltage of described the second power switch pipe declines, described the first capacitor discharge, produces the first electric current;
The input of described current detection circuit is connected with the second end of described the first electric capacity, detects described the first electric current;
Described electric current turns the input of potential circuit and the output of described current detection circuit is connected, and described the first electric current is converted into described the first voltage V0;
The in-phase input end of described the second comparator meets described predeterminated voltage V1, the inverting input of described the second comparator is connected with the output that described electric current turns potential circuit, for the size of more described the first voltage V0 and described voltage V1, produce described secondary diode current crossover point signal.
4. overvoltage crowbar according to claim 3, is characterized in that, described current detection circuit comprises: the first metal-oxide-semiconductor, the 3rd metal-oxide-semiconductor and the second electric capacity;
The source electrode of described the first metal-oxide-semiconductor connects external voltage, the grid of described the first metal-oxide-semiconductor is as the output of described current detection circuit, the drain electrode of described the first metal-oxide-semiconductor is connected with the first end of described the second electric capacity and the grid of described the first metal-oxide-semiconductor respectively, the second end of described the second electric capacity is connected with the source electrode of described the second metal-oxide-semiconductor, the drain electrode of described the second metal-oxide-semiconductor is as the input of described current detection circuit, and the grid of described the second metal-oxide-semiconductor connects bias voltage.
5. overvoltage crowbar according to claim 3, is characterized in that, described electric current turns potential circuit and comprises: the second metal-oxide-semiconductor, the 3rd electric capacity and the first resistance;
The source electrode of described the second metal-oxide-semiconductor connects external voltage, the grid of described the second metal-oxide-semiconductor turns the input of potential circuit as described electric current, the drain electrode of described the second metal-oxide-semiconductor is connected with the first end of described the 3rd electric capacity and the first end of described the first resistance respectively, and turn the output of potential circuit as described electric current, the equal ground connection of the second end of the second end of described the 3rd electric capacity and described the first resistance.
6. overvoltage crowbar according to claim 3, is characterized in that, described predeterminated voltage V1 is the reference voltage that reference voltage source produces.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105992435A (en) * | 2015-02-12 | 2016-10-05 | 上海含英微电子有限公司 | Anti-interference LED overvoltage protection module and anti-interference LED overvoltage protection system |
| CN106685236A (en) * | 2017-03-10 | 2017-05-17 | 绍兴光大芯业微电子有限公司 | Circuit structure for isolated switch power without auxiliary winding and with controllable primary side current |
| CN107911899A (en) * | 2017-11-23 | 2018-04-13 | 杰华特微电子（杭州）有限公司 | A kind of Switching Power Supply and LED drive circuit |
| CN111313365A (en) * | 2020-03-30 | 2020-06-19 | 福州京东方光电科技有限公司 | Overvoltage protection circuit, overvoltage protection method and display device |
| CN111725786A (en) * | 2019-03-19 | 2020-09-29 | 比亚迪股份有限公司 | Electronic equipment, power supply and power supply circuit thereof |
| CN112736851A (en) * | 2020-12-30 | 2021-04-30 | 上海晶丰明源半导体股份有限公司 | Voltage detection and processing circuit and method, switching power supply circuit and driving chip |
| CN115190682A (en) * | 2022-09-07 | 2022-10-14 | 深圳利普芯微电子有限公司 | Overvoltage protection circuit and LED drive power supply |
| CN107911899B (en) * | 2017-11-23 | 2024-04-23 | 杰华特微电子股份有限公司 | Switching power supply and LED drive circuit |
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Cited By (13)
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| CN105992435A (en) * | 2015-02-12 | 2016-10-05 | 上海含英微电子有限公司 | Anti-interference LED overvoltage protection module and anti-interference LED overvoltage protection system |
| CN105992435B (en) * | 2015-02-12 | 2019-03-15 | 上海含英微电子有限公司 | Anti-interference LED overvoltage protective module and anti-interference LED overvoltage protective system |
| CN106685236A (en) * | 2017-03-10 | 2017-05-17 | 绍兴光大芯业微电子有限公司 | Circuit structure for isolated switch power without auxiliary winding and with controllable primary side current |
| CN106685236B (en) * | 2017-03-10 | 2019-03-15 | 绍兴光大芯业微电子有限公司 | The controllable circuit structure without auxiliary winding isolation type switching power supply of primary current |
| CN107911899A (en) * | 2017-11-23 | 2018-04-13 | 杰华特微电子（杭州）有限公司 | A kind of Switching Power Supply and LED drive circuit |
| CN107911899B (en) * | 2017-11-23 | 2024-04-23 | 杰华特微电子股份有限公司 | Switching power supply and LED drive circuit |
| CN111725786A (en) * | 2019-03-19 | 2020-09-29 | 比亚迪股份有限公司 | Electronic equipment, power supply and power supply circuit thereof |
| CN111725786B (en) * | 2019-03-19 | 2022-09-16 | 比亚迪半导体股份有限公司 | Electronic equipment, power supply and power supply circuit thereof |
| CN111313365A (en) * | 2020-03-30 | 2020-06-19 | 福州京东方光电科技有限公司 | Overvoltage protection circuit, overvoltage protection method and display device |
| CN112736851A (en) * | 2020-12-30 | 2021-04-30 | 上海晶丰明源半导体股份有限公司 | Voltage detection and processing circuit and method, switching power supply circuit and driving chip |
| CN112736851B (en) * | 2020-12-30 | 2023-11-03 | 上海晶丰明源半导体股份有限公司 | Voltage detection and processing circuit and method, switching power supply circuit and driving chip |
| CN115190682A (en) * | 2022-09-07 | 2022-10-14 | 深圳利普芯微电子有限公司 | Overvoltage protection circuit and LED drive power supply |
| CN115190682B (en) * | 2022-09-07 | 2022-12-20 | 深圳利普芯微电子有限公司 | Overvoltage protection circuit and LED drive power supply |
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| CN103887770B (en) | 2017-10-24 |
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Effective date of registration: 20210127 Address after: No. 1600, Zixing Road, Minhang District, Shanghai 200241 Patentee after: BCD (SHANGHAI) MICRO-ELECTRONICS Ltd. Address before: 800 Yishan Road, Xuhui District, Shanghai Patentee before: BCD Semiconductor Manufacturing Ltd. |