CN203398768U - Low-cost AC input overvoltage protection circuit and switching power supply - Google Patents

Low-cost AC input overvoltage protection circuit and switching power supply Download PDF

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Publication number
CN203398768U
CN203398768U CN201320526544.2U CN201320526544U CN203398768U CN 203398768 U CN203398768 U CN 203398768U CN 201320526544 U CN201320526544 U CN 201320526544U CN 203398768 U CN203398768 U CN 203398768U
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China
Prior art keywords
voltage
power supply
switching tube
protection circuit
control chip
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Expired - Fee Related
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CN201320526544.2U
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Chinese (zh)
Inventor
廖邦勇
范继光
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Hunan tech-power Technology Co., Ltd.
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SONGSHUN ELECTRONIC (SHENZHEN) CO Ltd
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Priority to CN201320526544.2U priority Critical patent/CN203398768U/en
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Abstract

The utility model discloses a low-cost AC input overvoltage protection circuit and a switching power supply. The protection circuit comprises a voltages sampling end used for being connected to an AC/DC module output end of a power supply, a high-voltage suppression diode, a voltage-dividing resistor, a biasing resistor and a switching tube, wherein a control end of the switching tube is connected on a serial connecting junction of the voltage-dividing resistor and the biasing resistor for receiving high level to conduct the switching tube, one end of a switch channel of the switching tube is grounded, and the other end of the switch channel is sued for connecting a feedback input end of a power supply control chip. The low-cost AC input overvoltage protection circuit adopts the high-voltage suppression diode as a detection switch, can be broken down and conducted to provide a bias voltage for the biasing resistor upon overhigh input so as to conduct the switching tube, pulls down the voltage at the feedback end of the control chip to make the control chip stop working, can realize the automatic restoration function after the high voltage, realizes the detection protection of the input overvoltage with only four simple components, and has the advantages of being simple in structure, being safe and reliable, being low in cost, and being easy in wide popularization and application.

Description

Low-cost protection circuit against input over-voltage and the Switching Power Supply of exchanging
Technical field
The utility model relates to switch power technology field, is specifically related to a kind of low-cost protection circuit against input over-voltage and Switching Power Supply of exchanging.
Background technology
In field of switch power, generally all comprise the PWM type accessory power supply of promising main power conversion circuit power supply.Accessory power supply generally all directly utilizes the input high pressure (exchanging input through rectifies filtering) of main translation circuit to obtain required direct voltage through high frequency conversion.And in some electrical network less developed country or area, such as India, due to suitable unstable of AC-input voltage, time low when high, the power supply of can breaking moment when voltage is high.Thus, need to design a kind of protection circuit against input over-voltage, to reach protection object.But; an existing Switching Power Supply part is not done the design of input overvoltage protection; or just by set up the simple protective elements such as overvoltage protector or fuse at ac input end; and even other Switching Power Supplies have designed input overvoltage protection voltage also due to high cost, complex circuit designs and be difficult to apply.
Utility model content
The utility model provides a kind of low-cost protection circuit against input over-voltage and Switching Power Supply of exchanging, and can address the above problem.
A kind of low-cost protection circuit against input over-voltage that exchanges that the utility model embodiment provides, comprise: one for being connected to the voltage sample end of the AC/DC module output of power supply, one high pressure twin zener dioder, one divider resistance, one biasing resistor and a switching tube, wherein, voltage sample end, high pressure twin zener dioder, divider resistance and biasing resistor are connected in series successively to earth terminal, the control end of switching tube is connected on the node of connecting of divider resistance and biasing resistor and makes switching tube conducting to receive high level, switch passage one end ground connection of switching tube, the switch passage other end is for connecting the feedback input end of power supply control chip.
Preferably, control chip is pwm chip.
Preferably, the withstand voltage of described high pressure twin zener dioder is 350V.
Preferably, control chip is pwm chip.
Low cost based in above-described embodiment exchanges protection circuit against input over-voltage, the utility model embodiment also provides a kind of Switching Power Supply, comprise: AC/DC module, transformer, metal-oxide-semiconductor and control chip, AC/DC module is converted to interchange the primary coil of input transformer after direct current, transformer primary side coil passes through switch passage and a current-limiting resistance ground connection of metal-oxide-semiconductor successively, the switch that control chip is controlled metal-oxide-semiconductor makes to produce oscillating voltage on transformer primary side coil, this oscillating voltage is coupled to transformer secondary coil and powers to the load through filtration module, also comprise that the low cost described in above-described embodiment exchanges protection circuit against input over-voltage.
Preferably, also comprise that one for feeding back to switch power source output voltage the optocoupler feedback loop of control chip feedback end.
Technique scheme can be found out; because the utility model embodiment is usingd high pressure twin zener dioder and is used as sense switch; when input is too high, can breakdown conducting for providing bias voltage, biasing resistor make switching tube conducting; drag down rapidly the voltage of control chip feedback end; control chip is quit work; high pressure can be realized auto restore facility again later; only with four simple parts, realized the detection protection to input overvoltage; simple in structure and safe and reliable; with low cost, be easy to apply widely.
Accompanying drawing explanation
In order to be illustrated more clearly in the utility model embodiment 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 embodiment more of the present utility model, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the circuit theory diagrams of protective circuit in the utility model embodiment;
Fig. 2 is the circuit theory diagrams of the Switching Power Supply in the utility model embodiment.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is clearly and completely described, obviously, described embodiment is only the utility model part embodiment, rather than whole embodiment.Embodiment based in the utility model, those of ordinary skills are not making all other embodiment that obtain under creative work prerequisite, all belong to the scope of the utility model protection.
Embodiment:
The utility model embodiment provides a kind of low-cost protection circuit against input over-voltage that exchanges, as shown in Figure 1, comprise: for being connected to the voltage sample end J of the AC/DC module output of power supply, high pressure twin zener dioder DB, divider resistance R2, biasing resistor R15 and switching tube Q2, wherein, voltage sample end J, high pressure twin zener dioder DB, divider resistance R2 and biasing resistor R15 are connected in series successively to earth terminal, in the utility model embodiment, switching tube Q2 adopts NPN type triode, the base stage of NPN type triode is as the control end of switching tube, the collector electrode of NPN type triode is to the switch passage of emitter path as switching tube, the control end of switching tube Q2 is connected on the node of connecting of divider resistance R2 and biasing resistor R15 and makes switching tube conducting to receive high level, switch passage one end of switching tube Q2 (being the emitter of NPN type triode) ground connection, the switch passage other end (being the collector electrode of NPN type triode) is for connecting the feedback input end of power supply control chip.
In concrete switching power circuit, AC/DC module can be filtered the voltage after rectification to form stably through a filter circuit and be exported after voltage again, voltage sample end J in the utility model embodiment can be connected on the output of this filter circuit so, and effect can be better.
Be appreciated that; the parameter of each element of the protective circuit in the utility model embodiment can be adjusted according to the demand of Switching Power Supply; for example; the withstand voltage parameter of the high pressure twin zener dioder in the utility model embodiment protective circuit can be adjusted according to use occasion; the withstand voltage of the utility model embodiment mesohigh twin zener dioder is 350V, when the breakdown conducting of high pressure twin zener dioder during higher than 350V of the voltage of voltage sample end.If need the higher input voltage of monitoring, can select the high pressure twin zener dioder that withstand voltage is higher, therefore on circuit Adapter Property, there is higher suitability.
The Switching Power Supply that the control chip of usining is below pwm chip is introduced the specific works principle of protective circuit in the utility model embodiment as example.
This Switching Power Supply comprises: AC/DC module, transformer, metal-oxide-semiconductor and control chip; AC/DC module is converted to interchange the primary coil of input transformer after direct current; transformer primary side coil passes through switch passage and a current-limiting resistance ground connection of metal-oxide-semiconductor successively; the switch that control chip is controlled metal-oxide-semiconductor makes to produce oscillating voltage on transformer primary side coil; this oscillating voltage is coupled to transformer secondary coil and powers to the load through filtration module, also comprises that above-mentioned low cost exchanges protection circuit against input over-voltage.
Specifically as shown in Figure 2, this AC/DC module is usingd rectifier bridge that diode D1, D2, D3, D4 form as rectification core component, in the front end importation of AC/DC module, be provided with fuse F1, temperature coefficient of resistance RV1 and common mode disturbances and suppress coil L1, to guarantee the input safety of Switching Power Supply.
In AC/DC module the voltage of rectification through and the filtration of the capacitor C 1 that connects and electrochemical capacitor C2 after, obtain voltage comparatively stably, and voltage sample end J is connected to electrochemical capacitor C2 upper (being on the output of AC/DC module) just to obtain the detection to input voltage, voltage on electrochemical capacitor C2 offers the primary coil of transformer T1 simultaneously, the other end of the primary coil of transformer T1 is connected to earth terminal through metal-oxide-semiconductor Q1 and current-limiting resistance R4 successively, the grid of metal-oxide-semiconductor is as controlling the utmost point, between the source electrode of metal-oxide-semiconductor and drain electrode, form switch passage, at the two ends of the primary coil of transformer T1, be connected with series connection sustained diode 5 and energy consumption resistor (being formed by resistance R 5 and resistance R 6 parallel connections).
The control end GATE of pwm chip connects the grid of metal-oxide-semiconductor by resistance R 10, control conducting and the shutoff of metal-oxide-semiconductor, therefore can on transformer primary side coil, form oscillating voltage, this oscillating voltage is coupled to transformer T1 secondary coil and powers to the load through the filtration module of output.This filtration module is divided into rectifying and wave-filtering part, comprise double diode D7, D8, and be attempted by double diode two ends by resistance R 16 and capacitor C 8 filter branch in series, on the output of rectifying and wave-filtering part, also connect the π type filter circuit being formed by capacitor C 10, inductance L 2 and capacitor C 11, on the output of π type filter circuit, also connect a common mode interference filter inductance L 3, after inductance L 3, connect a voltage stabilizing didoe ZD1, to guarantee the stability to load output, in addition in filter capacitor C11 two ends parallel connection a bleeder resistance R24.
In order further to solve the stable problem of power supply, Switching Power Supply in the utility model embodiment also comprises an auxiliary power supply branch road, comprise the resistance R 7 of series connection successively, resistance R 14 and voltage stabilizing didoe ZD2, the plus earth of voltage stabilizing didoe ZD2, on the output of the AC/DC module of the other end connecting valve power supply of resistance R 7, the negative electrode of voltage stabilizing didoe ZD2 is the feeder ear VDD power supply of pwm chip, the capacitor C 6 for filtering also in parallel and for the electrochemical capacitor C3 of energy storage at voltage stabilizing didoe ZD2 two ends, simultaneously, the utility model embodiment has increased an ancillary coil, energy for coupling transformer primary coil, ancillary coil passes through resistance R 15 and diode D6 successively to the feeder ear VDD power supply of pwm chip, therefore can be continual and steady power for pwm chip.
In the utility model embodiment, Switching Power Supply also comprises that one for feeding back to switch power source output voltage the optocoupler feedback loop of control chip feedback end.Particular circuit configurations for optocoupler feedback loop can adopt various ways to realize, and specifically can adopt any one existing optocoupler feedback loop to carry out FEEDBACK CONTROL to the output of Switching Power Supply.In the utility model embodiment in order to realize more accurately FEEDBACK CONTROL, feedback loop comprises opto-coupler chip U2 and an a reference source chip U3, the light-emitting diodes tube anode of opto-coupler chip is connected to through resistance R 18 on the negative electrode of double diode of Switching Power Supply output, the negative electrode of double diode also connects the cathode terminal of a reference source chip U3 through resistance R 19, the anode tap ground connection of a reference source chip U3, the negative electrode of the light-emitting diode of opto-coupler chip U2 is also connected to the cathode terminal of a reference source chip U3; On electrochemical capacitor C11, connect a bleeder circuit, this bleeder circuit comprises resistance R 21 and the resistance R 22 of serial connection successively, resistance R 22 ground connection, and the dividing potential drop in resistance R 22 is input to a reference source voltage input end of a reference source chip U3.Owing to having added a reference source chip U3 in this feedback loop, opto-coupler chip U2Yuan limit is controlled more accurate.
The grounded emitter of the phototriode of opto-coupler chip U2 secondary, the collector electrode of phototriode is connected to the feedback end FB of pwm chip through a resistance R 1.As can be seen here, the Switching Power Supply in the utility model embodiment can have the function of two-way FEEDBACK CONTROL, and interchange input is detected with power supply output detections and combined, and assurance Switching Power Supply is inputted the safety and stability with output.
General input overvoltage protection circuit; because the electric pressure that will detect is higher; and do not isolate with major loop; so will be separately for overvoltage crowbar provides power supply circuits; this has not only increased complexity and the cost of accessory power supply; and this part circuit really connects and be connected altogether with main circuit, easily there is strong electromagnetic and damage.And protection circuit against input over-voltage in utility model embodiment only can be realized by a high pressure twin zener dioder and switching tube and biasing resistor, saved existing labyrinth.
High pressure twin zener dioder is directly linked the high-pressure side (being the output of AC/DC module) that exchanges output filtering, when AC network exceeds certain limit, when the high direct voltage after rectifying and wave-filtering exceeds the withstand voltage of diode, the conducting of high pressure twin zener dioder, through divider resistance dividing potential drop, make to obtain suitable bias voltage (high level) on biasing resistor, this bias voltage is applied to the base stage of NPN type triode, and then making the conducting of NPN type triode, its collector electrode is approximate short circuit over the ground.And the collector electrode of this NPN type triode is the feed back input pin (feedback end FB) that is connected on pulse modulation chip; control the duty ratio of pwm chip; the reduction of this collector potential drags down the feedback pin current potential of pulse modulation chip; make the discharge circuit upset of control chip inside; and then the trigger of control chip inside is reversed; the drive circuit that turn-offs metal-oxide-semiconductor, quits work power supply, reaches the object of protection.And when AC network is in normal range (NR), the not conducting of high pressure twin zener dioder, the base stage of NPN type triode is without current potential, in cut-off state, do not affect the normal operation of PWM chip, pulse modulation chip (control chip) is controlled the working method of control chip internal arithmetic circuit by optocoupler feedback loop.
A kind of low-cost interchange protection circuit against input over-voltage and the Switching Power Supply that above the utility model embodiment are provided are described in detail, applied specific case herein principle of the present utility model and execution mode are set forth, the explanation of above embodiment is just for helping to understand method of the present utility model and core concept thereof; , for one of ordinary skill in the art, according to thought of the present utility model, all will change in specific embodiments and applications, in sum, this description should not be construed as restriction of the present utility model meanwhile.

Claims (6)

1. low cost exchanges protection circuit against input over-voltage, it is characterized in that, comprise: one for being connected to the voltage sample end of the AC/DC module output of power supply, one high pressure twin zener dioder, one divider resistance, one biasing resistor and a switching tube, wherein, voltage sample end, high pressure twin zener dioder, divider resistance and biasing resistor are connected in series successively to earth terminal, the control end of switching tube is connected on the node of connecting of divider resistance and biasing resistor and makes switching tube conducting to receive high level, switch passage one end ground connection of switching tube, the switch passage other end is for connecting the feedback input end of power supply control chip.
2. the low-cost protection circuit against input over-voltage that exchanges as claimed in claim 1, is characterized in that, described switching tube adopts positive-negative-positive triode.
3. the low-cost protection circuit against input over-voltage that exchanges as claimed in claim 1, is characterized in that, the withstand voltage of described high pressure twin zener dioder is 350V.
4. low cost exchanges protection circuit against input over-voltage as claimed any one in claims 1 to 3, it is characterized in that, control chip is pwm chip.
5. Switching Power Supply; comprise: AC/DC module, transformer, metal-oxide-semiconductor and control chip; AC/DC module is converted to interchange the primary coil of input transformer after direct current; transformer primary side coil passes through switch passage and a current-limiting resistance ground connection of metal-oxide-semiconductor successively; the switch that control chip is controlled metal-oxide-semiconductor makes to produce oscillating voltage on transformer primary side coil; this oscillating voltage is coupled to transformer secondary coil and powers to the load through filtration module; it is characterized in that, also comprise that in the claims 1 to 3, the low cost described in any one exchanges protection circuit against input over-voltage.
6. Switching Power Supply as claimed in claim 5, is characterized in that, also comprises that one for feeding back to switch power source output voltage the optocoupler feedback loop of control chip feedback end.
CN201320526544.2U 2013-08-27 2013-08-27 Low-cost AC input overvoltage protection circuit and switching power supply Expired - Fee Related CN203398768U (en)

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CN201320526544.2U CN203398768U (en) 2013-08-27 2013-08-27 Low-cost AC input overvoltage protection circuit and switching power supply

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Application Number Priority Date Filing Date Title
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103474965A (en) * 2013-08-27 2013-12-25 崧顺电子(深圳)有限公司 Low-cost alternating-current input overvoltage protection circuit and switching power supply
CN104113779A (en) * 2014-07-09 2014-10-22 浪潮软件集团有限公司 Detection protection method for LNB power supply circuit in satellite television set top box
CN112467967A (en) * 2020-11-23 2021-03-09 无锡科索电子有限公司 Overvoltage protection structure of switching power supply
CN116865225A (en) * 2023-09-04 2023-10-10 深圳莱福德科技股份有限公司 Input overvoltage protection circuit

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103474965A (en) * 2013-08-27 2013-12-25 崧顺电子(深圳)有限公司 Low-cost alternating-current input overvoltage protection circuit and switching power supply
CN104113779A (en) * 2014-07-09 2014-10-22 浪潮软件集团有限公司 Detection protection method for LNB power supply circuit in satellite television set top box
CN104113779B (en) * 2014-07-09 2017-01-11 浪潮软件集团有限公司 Detection protection method for LNB power supply circuit in satellite television set top box
CN112467967A (en) * 2020-11-23 2021-03-09 无锡科索电子有限公司 Overvoltage protection structure of switching power supply
CN116865225A (en) * 2023-09-04 2023-10-10 深圳莱福德科技股份有限公司 Input overvoltage protection circuit
CN116865225B (en) * 2023-09-04 2024-01-05 深圳莱福德科技股份有限公司 Input overvoltage protection circuit

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C14 Grant of patent or utility model
GR01 Patent grant
C41 Transfer of patent application or patent right or utility model
TR01 Transfer of patent right

Effective date of registration: 20160825

Address after: 425000 Industrial Road, Hexi Industrial Zone, Lingling Industrial Zone, Lingling District, Yongzhou, Hunan

Patentee after: Hunan tech-power Technology Co., Ltd.

Address before: 518100 Guangdong city of Shenzhen province Baoan District Fuyong street community baishixia Longwangmiao Industrial Zone sixteenth, nineteenth

Patentee before: Songshun Electronic (Shenzhen) Co., Ltd.

CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20140115

Termination date: 20180827

CF01 Termination of patent right due to non-payment of annual fee