CN102201654A - 过流保护电路 - Google Patents

过流保护电路 Download PDF

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CN102201654A
CN102201654A CN2010101323473A CN201010132347A CN102201654A CN 102201654 A CN102201654 A CN 102201654A CN 2010101323473 A CN2010101323473 A CN 2010101323473A CN 201010132347 A CN201010132347 A CN 201010132347A CN 102201654 A CN102201654 A CN 102201654A
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operational amplifier
effect transistor
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CN102201654B (zh
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周海清
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Hongfujin Precision Industry Shenzhen Co Ltd
Hon Hai Precision Industry Co Ltd
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Hongfujin Precision Industry Shenzhen Co Ltd
Hon Hai Precision Industry Co Ltd
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Priority to CN201010132347.3A priority Critical patent/CN102201654B/zh
Priority to US12/790,971 priority patent/US20110235225A1/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1588—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load comprising at least one synchronous rectifier element
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

一种过流保护电路，包括一运算放大器、一第一电阻、一第二电阻及一场效应管。运算放大器的同向输入端与一供电电路的输出端相连，反向输入端通过第一电阻与同向输入端相连，第二电阻与第一电阻并联，场效应管的漏极通过一电阻与一电源相连并与供电电路的使能端相连，场效应管的栅极与运算放大器的输出端相连。上述过流保护电路对供电电路的负载起过流保护的作用。

Description

过流保护电路
技术领域
本发明涉及一种过流保护电路。
背景技术
主板上处理器与前端总线之间的端接电压(FSB terminater voltage)用于改变所述主板的前端总线频率。所述端接电压是由一端接电压供应电路提供的。然而现有的端接电压供应电路并没有采取过流保护措施，当输出电流过大时可能导致与端接电压供应电路相连的负载烧毁。
发明内容
鉴于以上内容，有必要提供一种可对供电电路的负载进行过流保护的过流保护电路。
一种过流保护电路，包括：
一运算放大器，所述运算放大器的同向输入端与一供电电路的输出端相连；
一第一电阻，所述运算放大器的反向输入端通过所述第一电阻与所述同向输入端相连；
一第二电阻，所述第二电阻与第一电阻并联，所述第二电阻的第一端与所述运算放大器的同向输入端相连，第二端与一负载相连；及
一场效应管，所述场效应管的漏极通过一第三电阻与一电源相连，还与所述供电电路的使能端相连，所述场效应管的栅极与所述运算放大器的输出端相连，源极接地，当所述供电电路的输出端的电流过大时，所述第一电阻两端的电压大于所述运算放大器的失调电压，所述运算放大器的输出端输出高电平，所述场效应管导通，此时场效应管的漏极为即低电平，所述供电电路的使能端即为低电平，所述供电电路停止工作，从而对所述负载进行过流保护。
上述过流保护电路通过所述运算放大器侦测所述第一电阻的电压来得知所述供电电路的输出端的电流变化。当所述供电电路输出的电流过大时，所述运算放大器输出高电平，以控制所述场效应管导通，从而使得所述供电电路的使能端为低电平，所述供电电路即停止工作，从而对所述负载起到过流保护的作用。
附图说明
图1是本发明过流保护电路的电路图。
主要元件符号说明
过流保护电路                100
端接电压供应电路            200
端接电压调节器              U1
电源端                      VCC
接地端                      GND
使能端                      EN
电压输入端                  VDD
参考电压输出端              V-ref
反馈端                      FB
补偿端                      COM
高端驱动器                  HD
低端驱动器                  LD
第一电源                    Vcc1
电容                        C1～C4
输入电压源                  V-in
电阻                        R1～R8
第一场效应管                Q1
第二场效应管                Q2
第二电源                    Vcc2
节点                            A、B
运算放大器                      U2
第三场效应管                    Q3
具体实施方式
下面结合附图及较佳实施方式对本发明作进一步详细描述：
请参考图1，本发明过流保护电路100的一种较佳实施方式用于对一端接电压供应电路200的负载进行过流保护。其他实施方式中，所述过流保护电路100可对其他电路的负载进行过流保护。
所述端接电压供应电路200包括一端接电压调节器U1、一第一场效应管Q1、一第二场效应管Q2、电阻R1～R4以及电容C1～C4。本实施方式中，所述端接电压调节器U1的型号为MIC5162。
所述端接电压调节器U1包括一电源端VCC、一接地端GND、一使能端EN、一电压输入端VDD、一参考电压输出端V-ref、一反馈端FB、一补偿端COM、一高端驱动器HD及一低端驱动器LD。所述端接电压调节器U1的高端驱动器HD用于输出一端接电压至负载。
所述端接电压调节器U1的电源端VCC与一第一电源Vcc1相连并通过一电容C1接地，电压输入端VDD与一输入电压源V-in相连，补偿端COM依次通过一电容C2及一电阻R1与所述反馈端FB相连，所述反馈端FB依次通过一电阻R2及一电容C3接地，高端驱动器HD与一第一场效应管Q1的栅极相连，低端驱动器LD与一第二场效应管Q2的栅极相连，参考电压输出端V-ref通过一电容C4与所述接地端GND相连，所述接地端GND接地。
所述第一场效应管Q1的漏极与一第二电源Vcc2相连，源极通过一电阻R3与所述高端驱动器HD相连。所述第二场效应管Q2的漏极与所述第一场效应管Q1的源极相连，所述第二场效应管Q2的源极接地并通过一电阻R4与所述低端驱动器LD相连。记所述第一场效应管Q1的源极与第二场效应管Q2的漏极之间的节点为“A”，记所述电容C3与所述电阻R2之间的节点为“B”，所述节点B用于与一负载相连。
所述端接电压调节器U1控制所述第一场效应管Q1及第二场效应管Q2导通或截止，所述第二电源Vcc2的电压经所述第一场效应管Q1分压后传送至所述节点A，所述节点A的电压即为所述端接电压供应电路200的输出电压。所述端接电压供应电路200的详细工作原理已属本领域所习知，在此不再赘述。
所述过流保护电路100包括一运算放大器U2、一第三场效应管Q3以及四个电阻R5～R8。
所述运算放大器U2的电源端与所述第一电源Vcc1相连，接地端接地，同相输入端连接于所述节点A，反相输入端通过所述电阻R5与所述同向输入端相连，输出端与所述第三场效应管Q3的栅极相连。
所述第三场效应管Q3的漏极通过所述电阻R6与所述第二电源Vcc2相连，还与所述端接电压调节器U1的使能端EN相连。所述第三场效应管Q3的源极接地。
所述电阻R5还与电阻R7串联后与所述电阻R8并联，所述电阻R8的一端与所述节点A相连，另一端与所述节点B相连。
所述电阻R5、R7的阻值远大于所述电阻R8的阻值，以使得所述节点A输出的电流绝大部分流经所述电阻R8。所述电阻R8的阻值非常小，以保证所述节点A的电压与节点B的电压相差较小。所述电阻R5、R7用于将流经所述电阻R8的电流变化转化为所述电阻R5、R7上的电压变化。
当所述端接电压供应电路200输出的电流正常时，所述电阻R5两端的电压小于所述运算放大器U2的失调(Offset)电压，根据运算放大器U2的工作原理，此时所述运算放大器U2的输出端无输出。所述第三场效应管Q3截止，所述第三场效应管Q3的漏极为高电平，从而使得所述端接电压调节器U1的使能端EN即为高电平，此时所述端接电压调节器U1得以持续正常工作。
当所述端接电压供应电路200输出的电流变大时，流经所述电阻R8的电流也逐渐增大，所述电阻R8两端的电压也相应的增大，所述电阻R5两端的电压也相应的增大。当流经电阻R8的电流达到一定值时，所述电阻R5两端的电压大于所述运算放大器U2的失调电压，此时所述运算放大器U2的输出端输出高电平。所述第三场效应管Q3导通，所述第三场效应管Q3的漏极为低电平，所述端接电压调节器U1的使能端EN即为低电平，所述端接电压调节器U1即停止工作，所述端接电压供应电路200无输出，从而对负载起到了过流保护作用。
上述过流保护电路100通过所述运算放大器U2侦测所述电阻R5的电压来得知所述端接电压供应电路200输出的电流变化，当所述端接电压供应电路200输出的电流过大时，所述运算放大器U2输出高电平，以控制所述第三场效应管Q3导通，从而使得所述端接电压调节器U1的使能端EN为低电平，所述端接电压调节器U1停止工作，所述端接电压供应电路200无输出，从而对所述负载起到过流保护的作用。

Claims (3)

1.一种过流保护电路，包括：
一运算放大器，所述运算放大器的同向输入端与一供电电路的输出端相连；
一第一电阻，所述运算放大器的反向输入端通过所述第一电阻与所述同向输入端相连；
一第二电阻，所述第二电阻与第一电阻并联，所述第二电阻的第一端与所述运算放大器的同向输入端相连，第二端与一负载相连；及
一场效应管，所述场效应管的漏极通过一第三电阻与一电源相连，还与所述供电电路的使能端相连，所述场效应管的栅极与所述运算放大器的输出端相连，源极接地，当所述供电电路的输出端的电流过大时，所述第一电阻两端的电压大于所述运算放大器的失调电压，所述运算放大器的输出端输出高电平，所述场效应管导通，此时场效应管的漏极为即低电平，所述供电电路的使能端即为低电平，所述供电电路停止工作，从而对所述负载进行过流保护。
2.如权利要求1所述的过流保护电路，其特征在于：所述第二电阻的阻值远大于所述第一电阻的阻值。
3.如权利要求1所述的过流保护电路，其特征在于：所述第二电阻的第二端还通过一电容接地。
CN201010132347.3A 2010-03-25 2010-03-25 过流保护电路 Expired - Fee Related CN102201654B (zh)

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US12/790,971 US20110235225A1 (en) 2010-03-25 2010-05-31 Overcurrent protection circuit

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CN103901994A (zh) * 2012-12-26 2014-07-02 鸿富锦精密工业（深圳）有限公司 电源电路

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US4979066A (en) * 1988-03-04 1990-12-18 Alps Electric Co., Ltd. Loading controlling apparatus
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US7508182B1 (en) * 2005-10-26 2009-03-24 Semtech Corporation Method and apparatus for improved current mode control for large conversion ratio synchronous buck converter with lossless current sense

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Publication number Priority date Publication date Assignee Title
US4979066A (en) * 1988-03-04 1990-12-18 Alps Electric Co., Ltd. Loading controlling apparatus
US7508182B1 (en) * 2005-10-26 2009-03-24 Semtech Corporation Method and apparatus for improved current mode control for large conversion ratio synchronous buck converter with lossless current sense
CN101034798A (zh) * 2007-04-06 2007-09-12 广州金升阳科技有限公司 一种电源变换器输出保护电路

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Application publication date: 20110928

Assignee: Hongfujin Precision Electronics (Tianjin) Co., Ltd.

Assignor: Hon Hai Precision Industry Co., Ltd. | Hong Fujin Precision Industry (Shenzhen) Co., Ltd.

Contract record no.: 2014990000931

Denomination of invention: Crest factor overcurrent protection circuit applied to electronic ballast

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