CN111614062A - Short circuit protection circuit of multiple output power supply - Google Patents

Short circuit protection circuit of multiple output power supply Download PDF

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CN111614062A
CN111614062A CN202010419056.6A CN202010419056A CN111614062A CN 111614062 A CN111614062 A CN 111614062A CN 202010419056 A CN202010419056 A CN 202010419056A CN 111614062 A CN111614062 A CN 111614062A
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power supply
resistor
output power
voltage
triode
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CN111614062B (en
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温志伟
许小虎
林旭平
谭郑生
孔波
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Zhuhai Galaxy Nike Technology Co ltd
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H02H7/1213Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters

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Abstract

本发明公开了一种多路输出电源的短路保护电路,包括第一三极管、第二三极管、第一电阻、第二电阻、第三电阻和充电电容;第一三极管的基极通过第一电阻与多路输出电源的第一电压端连接,第一三极管的集电极通过第二电阻与第二三极管的基极连接且通过第三电阻与第二三极管的发射极连接,第一三极管的发射极通过充电电容接地,充电电容与多路输出电源的第二电压端连接;第二三极管的集电极与多路输出电源的PWM输出控制端连接且发射极接地;第一三极管和第二三极管在多路输出电源的第一电压端受输出端短路影响而降低时由截止状态转换为导通状态;本发明在多路输出电源的任一输出端短路的时候,都能对多路输出电源进行有效的保护。

Figure 202010419056

The invention discloses a short-circuit protection circuit of a multi-channel output power supply, comprising a first triode, a second triode, a first resistor, a second resistor, a third resistor and a charging capacitor; a base of the first triode The electrode is connected to the first voltage terminal of the multi-output power supply through the first resistor, the collector of the first triode is connected to the base of the second triode through the second resistor, and is connected to the second triode through the third resistor. The emitter of the first triode is connected to the ground through the charging capacitor, and the charging capacitor is connected to the second voltage terminal of the multi-output power supply; the collector of the second triode is connected to the PWM output control terminal of the multi-output power supply connected and the emitter is grounded; the first triode and the second triode are converted from the off state to the on state when the first voltage end of the multi-channel output power supply is reduced by the influence of the output end short circuit; the present invention is used in the multi-channel output When any output terminal of the power supply is short-circuited, it can effectively protect the multi-output power supply.

Figure 202010419056

Description

多路输出电源的短路保护电路Short circuit protection circuit of multiple output power supply

技术领域technical field

本发明涉及电路保护技术领域,特别涉及一种多路输出电源的短路保护电路。The invention relates to the technical field of circuit protection, in particular to a short-circuit protection circuit for multiple output power supplies.

背景技术Background technique

典型的反激电源如图5所示,反激电源由启动电路、电源管理芯片、反馈电路和耦合变压器构成,其中反馈电路由光电耦合器和TL431器件组成,多路输出电源中的主输出绕组经反馈电路检测输出电压,与电源管理芯片形成电压环路控制,当主输出绕组短路或者轻重载的时候,通过反馈电路形成闭环控制,达到稳定电源保护电路作用。传统的多路输出反激电路,在理想条件下,如果其中一路输出端短路,其他绕组将按实际匝数比例进行缩放,辅助绕组同样将会降低电压,当达到欠压点时,电源芯片将会重新启动,从而达到输出端短路保护作用,直到短路消失。但是实际情况下,由于各绕组之间的线路阻抗及漏感等因素在里面,所有输出端短路并不是按照匝数比进行缩放,这就会产生以下问题:可能其中一路短路,电源还在工作,直到输出端烧毁。A typical flyback power supply is shown in Figure 5. The flyback power supply consists of a startup circuit, a power management chip, a feedback circuit and a coupling transformer. The feedback circuit consists of an optocoupler and a TL431 device. The main output winding in the multi-output power supply The output voltage is detected by the feedback circuit, and forms a voltage loop control with the power management chip. When the main output winding is short-circuited or under light and heavy load, a closed-loop control is formed through the feedback circuit to achieve the function of a stable power supply protection circuit. In a traditional multi-output flyback circuit, under ideal conditions, if one of the outputs is short-circuited, the other windings will be scaled according to the actual number of turns, and the auxiliary winding will also reduce the voltage. When the undervoltage point is reached, the power chip will It will restart, so as to achieve short-circuit protection at the output until the short-circuit disappears. However, in practice, due to factors such as line impedance and leakage inductance between windings, all output short circuits are not scaled according to the turns ratio, which will cause the following problems: one of them may be short-circuited and the power supply is still working. , until the output burns out.

发明内容SUMMARY OF THE INVENTION

本发明所要解决的技术问题是:提供了一种多路输出电源的短路保护电路,以在多路输出电源的任一输出端短路的时候,都能对多路输出电源进行有效的保护。The technical problem to be solved by the present invention is to provide a short circuit protection circuit for multiple output power supplies, so as to effectively protect the multiple output power supplies when any output terminal of the multiple output power supplies is short-circuited.

为了解决上述技术问题,本发明采用的技术方案为:In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

多路输出电源的短路保护电路,包括第一三极管、第二三极管、第一电阻、第二电阻、第三电阻和充电电容;The short-circuit protection circuit of the multi-channel output power supply includes a first transistor, a second transistor, a first resistor, a second resistor, a third resistor and a charging capacitor;

所述第一三极管的基极通过所述第一电阻与多路输出电源的第一电压端连接,所述第一三极管的集电极通过所述第二电阻与所述第二三极管的基极连接且通过所述第三电阻与所述第二三极管的发射极连接,所述第一三极管的发射极通过所述充电电容接地,所述充电电容与所述多路输出电源的第二电压端连接;The base of the first triode is connected to the first voltage terminal of the multi-output power supply through the first resistor, and the collector of the first triode is connected to the second third through the second resistor. The base of the transistor is connected to the emitter of the second transistor through the third resistor, the emitter of the first transistor is grounded through the charging capacitor, and the charging capacitor is connected to the The second voltage terminal of the multi-channel output power supply is connected;

所述第二三极管的集电极与所述多路输出电源的PWM输出控制端连接且发射极接地;The collector of the second transistor is connected to the PWM output control terminal of the multi-output power supply, and the emitter is grounded;

所述第一三极管为PNP三极管,所述第二三极管为NPN三极管;The first triode is a PNP triode, and the second triode is an NPN triode;

所述第一三极管和所述第二三极管在所述多路输出电源的第一电压端受输出端短路影响而降低时由截止状态转换为导通状态。The first triode and the second triode are converted from an off state to an on state when the first voltage terminal of the multi-channel output power supply is lowered due to the influence of the output terminal short circuit.

本发明的有益效果在于:多路输出电源的短路保护电路,在多路输出电源正常工作时,由多路输出电源的第二电压端对充电电容进行充电,直到达到稳定电压;当多路输出电源的任一输出端短路的时候,多路输出电源的第一电压端发生变化,使得第一三极管由截止状态转换为导通状态,此时,由于第一三极管为PNP三极管,因此,与第一三极管的发射极连接的充电电容开始放电,在充电电容的电压和第三电阻的驱动下,第二二极管开始导通,使得与第二三极管的集电极连接的多路输出电源的PWM输出控制端开始对地放电,以使得PWM输出控制端的电压开始下降,从而切断PWM输出端的输出,以对多路输出电源进行有效的保护。即本发明通过低成本搭建电路,解决了变压器各绕组间漏感以及等效电阻等不同因数对输出短路的影响,从而在多路输出电源的任一输出端短路的时候,都能对多路输出电源进行有效的保护。The beneficial effects of the present invention are: the short-circuit protection circuit of the multi-channel output power supply, when the multi-channel output power supply works normally, the charging capacitor is charged by the second voltage terminal of the multi-channel output power supply until the stable voltage is reached; When any output terminal of the power supply is short-circuited, the first voltage terminal of the multi-channel output power supply changes, so that the first transistor is converted from the off state to the on state. At this time, since the first transistor is a PNP transistor, Therefore, the charging capacitor connected to the emitter of the first triode begins to discharge, and driven by the voltage of the charging capacitor and the third resistor, the second diode begins to conduct, so that it is connected to the collector of the second triode. The PWM output control terminal of the connected multi-output power supply starts to discharge to the ground, so that the voltage of the PWM output control terminal starts to drop, thereby cutting off the output of the PWM output terminal, so as to effectively protect the multi-output power supply. That is, the present invention solves the influence of different factors such as leakage inductance and equivalent resistance between the transformer windings on the output short circuit by building a circuit at low cost, so that when any output end of the multi-channel output power supply is short-circuited, the multi-channel output power supply can be short-circuited. The output power is effectively protected.

附图说明Description of drawings

图1为本发明实施例的多路输出电源的短路保护电路与多路输出电源的配合连接示意图;1 is a schematic diagram of the coordinated connection between a short-circuit protection circuit of a multi-channel output power supply and a multi-channel output power supply according to an embodiment of the present invention;

图2为本发明实施例的多路输出电源的短路保护电路与多路输出电源的启动电路、电源管理芯片、反馈电路之间配合连接的具体电路示意图;FIG. 2 is a specific circuit schematic diagram of the cooperative connection between the short-circuit protection circuit of the multi-channel output power supply and the start-up circuit, the power management chip and the feedback circuit of the multi-channel output power supply according to the embodiment of the present invention;

图3为本发明另一实施例的多路输出电源的短路保护电路与多路输出电源的配合连接示意图;3 is a schematic diagram of the cooperative connection between a short-circuit protection circuit of a multi-channel output power supply and a multi-channel output power supply according to another embodiment of the present invention;

图4为本发明另一实施例的多路输出电源的短路保护电路与多路输出电源的启动电路、电源管理芯片、反馈电路之间配合连接的具体电路示意图;4 is a specific circuit schematic diagram of the cooperative connection between the short-circuit protection circuit of the multi-output power supply and the start-up circuit, the power management chip, and the feedback circuit of the multi-output power supply according to another embodiment of the present invention;

图5为现有技术中的多路输出电源的电路示意图。FIG. 5 is a schematic circuit diagram of a multi-channel output power supply in the prior art.

标号说明:Label description:

C1-C5均为电容,其中,C1、第一电容;C2、充电电容;C1-C5 are all capacitors, among which, C1, the first capacitor; C2, the charging capacitor;

D1-D6均为二极管,其中,D1、第一二极管;D2/D4、第二二极管;D3、第三二极管;D1-D6 are all diodes, wherein D1, the first diode; D2/D4, the second diode; D3, the third diode;

Q1、第一三极管;Q2、第二三极管;Q1, the first transistor; Q2, the second transistor;

R1-R19均为电阻,其中,R1/R9、第一电阻;R2、第二电阻、R3、第三电阻;R4、第四电阻;R5、第五电阻;R6、第六电阻;R7、第七电阻;R8、第八电阻;R1-R19 are all resistors, among which, R1/R9, the first resistor; R2, the second resistor, R3, the third resistor; R4, the fourth resistor; R5, the fifth resistor; R6, the sixth resistor; R7, the first resistor Seven resistors; R8, eighth resistors;

U1、光电耦合器;U2、TL431器件;U3、电源管理芯片;U1, optocoupler; U2, TL431 device; U3, power management chip;

V1/V2、多路输出电源的支路输出端;V3、多路输出电源的主输出端;Vcc、供电电压;Vin、输入直流高压。V1/V2, branch output terminal of multi-channel output power supply; V3, main output terminal of multi-channel output power supply; Vcc, power supply voltage; Vin, input DC high voltage.

具体实施方式Detailed ways

为详细说明本发明的技术内容、所实现目的及效果,以下结合实施方式并配合附图予以说明。In order to describe in detail the technical content, achieved objects and effects of the present invention, the following descriptions are given with reference to the embodiments and the accompanying drawings.

请参照图1至图4,多路输出电源的短路保护电路,包括第一三极管、第二三极管、第一电阻、第二电阻、第三电阻和充电电容;Please refer to FIG. 1 to FIG. 4 , the short-circuit protection circuit of the multi-channel output power supply includes a first transistor, a second transistor, a first resistor, a second resistor, a third resistor and a charging capacitor;

所述第一三极管的基极通过所述第一电阻与多路输出电源的第一电压端连接,所述第一三极管的集电极通过所述第二电阻与所述第二三极管的基极连接且通过所述第三电阻与所述第二三极管的发射极连接,所述第一三极管的发射极通过所述充电电容接地,所述充电电容与所述多路输出电源的第二电压端连接;The base of the first triode is connected to the first voltage terminal of the multi-output power supply through the first resistor, and the collector of the first triode is connected to the second third through the second resistor. The base of the transistor is connected to the emitter of the second transistor through the third resistor, the emitter of the first transistor is grounded through the charging capacitor, and the charging capacitor is connected to the The second voltage terminal of the multi-channel output power supply is connected;

所述第二三极管的集电极与所述多路输出电源的PWM输出控制端连接且发射极接地;The collector of the second transistor is connected to the PWM output control terminal of the multi-output power supply, and the emitter is grounded;

所述第一三极管为PNP三极管,所述第二三极管为NPN三极管;The first triode is a PNP triode, and the second triode is an NPN triode;

所述第一三极管和所述第二三极管在所述多路输出电源的第一电压端受输出端短路影响而降低时由截止状态转换为导通状态。The first triode and the second triode are converted from an off state to an on state when the first voltage terminal of the multi-channel output power supply is lowered due to the influence of the output terminal short circuit.

从上述描述可知,本发明的有益效果在于:在多路输出电源正常工作时,由多路输出电源的第二电压端对充电电容进行充电,直到达到稳定电压;当多路输出电源的任一输出端短路的时候,多路输出电源的第一电压端发生变化,使得第一三极管由截止状态转换为导通状态,此时,由于第一三极管为PNP三极管,因此,与第一三极管的发射极连接的充电电容开始放电,在充电电容的电压和第三电阻的驱动下,第二二极管开始导通,使得与第二三极管的集电极连接的多路输出电源的PWM输出控制端开始对地放电,以使得PWM输出控制端的电压开始下降,从而切断PWM输出端的输出,以对多路输出电源进行有效的保护。即本发明通过低成本搭建电路,解决了变压器各绕组间漏感以及等效电阻等不同因数对输出短路的影响,从而在多路输出电源的任一输出端短路的时候,都能对多路输出电源进行有效的保护。It can be seen from the above description that the beneficial effects of the present invention are: when the multi-channel output power supply is working normally, the charging capacitor is charged by the second voltage terminal of the multi-channel output power supply until a stable voltage is reached; when any one of the multi-channel output power supply When the output terminal is short-circuited, the first voltage terminal of the multi-channel output power supply changes, so that the first transistor is converted from the off state to the on state. At this time, since the first transistor is a PNP transistor, the The charging capacitor connected to the emitter of a triode begins to discharge. Driven by the voltage of the charging capacitor and the third resistor, the second diode begins to conduct, so that the multiplexer connected to the collector of the second triode starts to conduct. The PWM output control terminal of the output power supply starts to discharge to the ground, so that the voltage of the PWM output control terminal starts to drop, thereby cutting off the output of the PWM output terminal, so as to effectively protect the multi-channel output power supply. That is, the present invention solves the influence of different factors such as leakage inductance and equivalent resistance between the transformer windings on the output short circuit by building a circuit at low cost, so that when any output end of the multi-channel output power supply is short-circuited, the multi-channel output power supply can be short-circuited. The output power is effectively protected.

进一步地,还包括第一二极管、第四电阻、第五电阻和第六电阻,所述第一电压端和所述PWM输出控制端均为所述多路输出电源的供电电压端;Further, it also includes a first diode, a fourth resistor, a fifth resistor and a sixth resistor, and the first voltage terminal and the PWM output control terminal are both the power supply voltage terminals of the multi-channel output power supply;

所述第二三极管的集电极与所述多路输出电源的供电电压端之间连接有所述第四电阻;The fourth resistor is connected between the collector of the second transistor and the supply voltage terminal of the multi-output power supply;

所述第一三极管的发射极通过所述充电电容接地,所述充电电容与所述多路输出电源的第二电压端连接具体为:The emitter of the first triode is grounded through the charging capacitor, and the connection between the charging capacitor and the second voltage terminal of the multi-channel output power supply is as follows:

所述第一三极管的发射极同时与所述充电电容的一端、所述第五电阻的一端连接,所述充电电容的另一端接地且通过所述第六电阻与所述第一三极管的基极连接,所述第五电阻的另一端与所述第一二极管的阴极连接,所述第一二极管的阳极与所述多路输出电源的电源管理芯片的基准电压端连接;The emitter of the first triode is connected to one end of the charging capacitor and one end of the fifth resistor at the same time, and the other end of the charging capacitor is grounded and connected to the first triode through the sixth resistor The base of the tube is connected, the other end of the fifth resistor is connected to the cathode of the first diode, and the anode of the first diode is connected to the reference voltage terminal of the power management chip of the multi-output power supply connect;

所述充电电容的稳态电压小于所述第六电阻在所述多路输出电源的正常状态下的两端电压且大于所述第六电阻在所述多路输出电源的输出端短路的两端电压。The steady-state voltage of the charging capacitor is smaller than the voltage at both ends of the sixth resistor in the normal state of the multi-channel output power supply and is greater than the two ends of the sixth resistor short-circuited at the output end of the multi-channel output power supply Voltage.

从上述描述可知,当对充电电容进行充电到稳态电压后,由于小于第六电阻在多路输出电源的正常状态下的两端电压,而第六电阻设置在第一三极管的基极,因此,对于PNP三极管来说,在多路输出电源正常工作时,第一三极管处于截止状态。当任一输出端短路的时候,按照匝数比等效电压计算,多路输出电源的供电电压端的供电电压会被拉低,但是由于各输出端存在漏感及等效阻抗等问题,不能保证所有输出端短路时,供电电压都能拉低到欠电压保护点;此时,供电电压开始拉低,使得第六电阻的两端电压开始下降,由于充电电容的稳态电压大于第六电阻在多路输出电源的输出端短路的两端电压,即使得第一三极管导通,由充电电容开始放电,在充电电容的电压和第三电阻的驱动下,第二二极管开始导通,使得与第二三极管的集电极连接的供电电压端开始对地迅速放电,其中,多路输出电源的电源管理芯片的驱动电压端连接供电电压端,以使得供电电压端的电压触发电源管理芯片的驱动电压端的欠压保护点,从而切断PWM输出端的输出,以对多路输出电源进行有效的保护。It can be seen from the above description that when the charging capacitor is charged to the steady-state voltage, the sixth resistor is set at the base of the first triode because it is smaller than the voltage across the sixth resistor in the normal state of the multi-output power supply. , therefore, for the PNP triode, when the multi-channel output power supply works normally, the first triode is in an off state. When any output terminal is short-circuited, according to the equivalent voltage calculation of the turns ratio, the power supply voltage of the power supply voltage terminal of the multi-output power supply will be pulled down. However, due to the leakage inductance and equivalent impedance of each output terminal, it is not guaranteed. When all the output terminals are short-circuited, the power supply voltage can be pulled down to the undervoltage protection point; at this time, the power supply voltage starts to be pulled down, so that the voltage across the sixth resistor begins to drop, because the steady-state voltage of the charging capacitor is greater than that of the sixth resistor at The output terminal of the multi-channel output power supply is short-circuited to the voltage at both ends, that is, the first transistor is turned on, and the charging capacitor starts to discharge. Driven by the voltage of the charging capacitor and the third resistor, the second diode starts to conduct. , so that the power supply voltage terminal connected to the collector of the second triode begins to discharge rapidly to the ground, wherein the driving voltage terminal of the power management chip of the multi-channel output power supply is connected to the power supply voltage terminal, so that the voltage of the power supply voltage terminal triggers the power management The under-voltage protection point of the driving voltage end of the chip cuts off the output of the PWM output end to effectively protect the multi-channel output power supply.

进一步地,所述第一电阻和所述第六电阻的阻值比为X,所述充电电容的稳态电压小于所述多路输出电源在正常状态下的供电电压/(X+1)且大于所述多路输出电源在任何一路输出电源短路时的供电电压/(X+1)。Further, the resistance ratio of the first resistor and the sixth resistor is X, and the steady-state voltage of the charging capacitor is less than the power supply voltage of the multi-channel output power supply in a normal state/(X+1) and It is greater than the supply voltage/(X+1) of the multi-channel output power supply when any one of the output power supplies is short-circuited.

从上述描述可知,当限制充电电容的稳态电压小于多路输出电源在正常状态下的供电电压/(X+1)且大于多路输出电源在任何一路输出电源短路时的供电电压/(X+1),即假设多路输出电源在正常状态下的供电电压为16V,在任何一路输出电源短路时的供电电压为12V,第一电阻和第六电阻的阻值比为2,则充电电容的稳态电压小于5.33V大于4V,以保证在任何一路输出电源短路,第一三极管的基极和发射极的电压发生变化,以将第一三极管由截止状态转换为导通状态。It can be seen from the above description that when the steady-state voltage of the limiting charging capacitor is less than the power supply voltage of the multi-channel output power supply in the normal state/(X+1) and greater than the supply voltage of the multi-channel output power supply when any output power supply is short-circuited/(X +1), that is, assuming that the power supply voltage of the multi-channel output power supply is 16V in normal state, the supply voltage when any output power supply is short-circuited is 12V, and the resistance ratio of the first resistor and the sixth resistor is 2, then the charging capacitor The steady-state voltage is less than 5.33V and greater than 4V, to ensure that any output power supply is short-circuited, and the voltage of the base and emitter of the first transistor changes, so as to convert the first transistor from the off state to the on state. .

进一步地,所述多路输出电源的供电电压端还连接有第一电容,所述充电电容、所述第二电阻和所述第三电阻之间形成的放电常数大于所述第一电容和所述第四电阻之间形成的放电常数的10倍。Further, the power supply voltage terminal of the multi-channel output power supply is also connected with a first capacitor, and the discharge constant formed between the charging capacitor, the second resistor and the third resistor is greater than the first capacitor and the third resistor. 10 times the discharge constant formed between the fourth resistors.

从上述描述可知,通过对放电常数的限制,使得充电电容的两端电压通过第一三极管、第二电阻和第三电阻对地放电的速度要慢于供电电压通过第四电阻对地放电到电压触发电源管理芯片的驱动电压端的欠压保护点,以保证供电电压端的供电电压能触发电源管理芯片的驱动电压端的欠压保护点。It can be seen from the above description that by limiting the discharge constant, the voltage across the charging capacitor discharges to the ground through the first triode, the second resistor and the third resistor is slower than the power supply voltage discharges to the ground through the fourth resistor To the undervoltage protection point of the driving voltage terminal of the voltage-triggered power management chip, to ensure that the power supply voltage of the power supply voltage terminal can trigger the undervoltage protection point of the driving voltage terminal of the power management chip.

进一步地,还包括与所述多路输出电源的辅助供电支路的数量对应的第二二极管、第七电阻和第八电阻,所述PWM输出控制端为所述多路输出电源的光耦检测输出电压端;Further, it also includes a second diode, a seventh resistor and an eighth resistor corresponding to the number of auxiliary power supply branches of the multi-channel output power supply, and the PWM output control terminal is the light of the multi-channel output power supply. Coupling detection output voltage terminal;

所述第一三极管的基极通过所述第一电阻与多路输出电源的第一电压端连接具体为:The connection between the base of the first transistor and the first voltage terminal of the multi-channel output power supply through the first resistor is as follows:

所述第一三极管的基极与第一电阻的一端连接,所述第一电阻的另一端同时与多个所述第二二极管的阳极连接,每一个所述第二二极管的阴极分别与所述多路输出电源的一个辅助供电支路的支路输出端连接;The base of the first triode is connected to one end of the first resistor, and the other end of the first resistor is connected to the anodes of the plurality of second diodes at the same time, each of the second diodes The cathodes are respectively connected with the branch output ends of an auxiliary power supply branch of the multi-output power supply;

所述第一三极管的发射极通过所述充电电容接地,所述充电电容与所述多路输出电源的第二电压端连接具体为:The emitter of the first triode is grounded through the charging capacitor, and the connection between the charging capacitor and the second voltage terminal of the multi-channel output power supply is as follows:

所述第一三极管的发射极同时与所述充电电容的一端、所述第七电阻的一端、所述第八电阻的一端连接,所述充电电容的另一端与所述第七电阻的另一端同时接地,所述第八电阻的另一端与所述多路输出电源的主输出端连接;The emitter of the first transistor is simultaneously connected to one end of the charging capacitor, one end of the seventh resistor, and one end of the eighth resistor, and the other end of the charging capacitor is connected to the seventh resistor. The other end is grounded at the same time, and the other end of the eighth resistor is connected to the main output end of the multi-output power supply;

所述充电电容的稳态电压大于a且小于a+b,所述a为所述第一三极管上发射极和基极之间的导通电压,所述b为所述多路输出电源的所有辅助供电支路的正常电压的最低值。The steady-state voltage of the charging capacitor is greater than a and less than a+b, where a is the conduction voltage between the emitter and the base of the first transistor, and b is the multi-channel output power supply The lowest value of the normal voltage of all auxiliary power supply branches.

从上述描述可知,限制充电电容的稳态电压,使得在多路输出电源的正常状态下,第一三极管的发射极与基极之间的电压差小于导通电压而处于截止状态。当任一输出端短路的时候,其中一个第二二极管导通,使得第一二极管的基极电压迅速下降,由于充电电容的稳态电压大于第一三极管上发射极和基极之间的导通电压,则此时第一二极管导通,使得第二二极管的基极电压迅速上升,之后第二二极管导通,以使得光电耦合器饱和导通,将原本的电源管理芯片的PWM输出端关段。随后,多路输出电源的主输出端迅速下降,由充电电容对第一电阻、第二电阻和第三电阻进行放电,来维持对第二二极管的导通,因此辅电会关闭一段时间;而当充电电容的电压下降到无法使得第一三极管导通时,辅电重启,如果多路输出电源的短路情况仍然存在,则会将充电电容充电至第一三极管的导通电压以上时,再次将电源管理芯片的PWM输出端关闭,电源再次进行进入重启状态,后续并反复重启,电源进入“打嗝”保护模式;而当多路输出电源的短路情况已经消除的情况下,电源重启,由于充电延时,充电电容的电压充电至第一三极管的导通电压以上时,支路电压已经上升,使得第一二极管和第二二极管保持关段,辅电能正常启动并工作。It can be seen from the above description that the steady-state voltage of the charging capacitor is limited, so that in the normal state of the multi-output power supply, the voltage difference between the emitter and the base of the first triode is less than the on-voltage and is in the off-state. When any output terminal is short-circuited, one of the second diodes is turned on, causing the base voltage of the first diode to drop rapidly, because the steady-state voltage of the charging capacitor is greater than the emitter and base of the first transistor. If the conduction voltage between the poles is high, the first diode is turned on at this time, so that the base voltage of the second diode rises rapidly, and then the second diode is turned on, so that the optocoupler is saturated and turned on, Turn off the PWM output of the original power management chip. Subsequently, the main output terminal of the multi-output power supply drops rapidly, and the first resistor, the second resistor and the third resistor are discharged by the charging capacitor to maintain the conduction of the second diode, so the auxiliary power will be turned off for a period of time. ; When the voltage of the charging capacitor drops to the point where the first transistor cannot be turned on, the auxiliary power is restarted. If the short circuit of the multi-channel output power supply still exists, the charging capacitor will be charged to the conduction of the first transistor. When the voltage is above, the PWM output of the power management chip is turned off again, the power supply enters the restart state again, and then restarts repeatedly, the power supply enters the "hiccup" protection mode; and when the short-circuit condition of the multi-output power supply has been eliminated, the When the power supply is restarted, due to the charging delay, when the voltage of the charging capacitor is charged above the turn-on voltage of the first triode, the branch voltage has risen, so that the first diode and the second diode remain off, and the auxiliary energy Starts normally and works.

进一步地,所述第九电阻大于所述第八电阻。Further, the ninth resistance is greater than the eighth resistance.

从上述描述可知,这样充电电容和第九电阻之间的放电常数大于充电电容和第八电阻的充电常数,以减慢充电电容的放电速度。It can be seen from the above description that the discharge constant between the charging capacitor and the ninth resistor is greater than the charging constant between the charging capacitor and the eighth resistor, so as to slow down the discharging speed of the charging capacitor.

进一步地,还包括第三二极管,所述第一三极管的发射极同时与所述充电电容的一端、所述第七电阻的一端、所述第八电阻的一端连接具体为:Further, it also includes a third diode, and the emitter of the first triode is connected to one end of the charging capacitor, one end of the seventh resistor, and one end of the eighth resistor at the same time. Specifically:

所述第一三极管的发射极同时与所述充电电容的一端、所述第三二极管的阴极连接,所述第三二极管的阳极同时与所述第七电阻的一端、所述第八电阻的一端连接。The emitter of the first triode is connected to one end of the charging capacitor and the cathode of the third diode at the same time, and the anode of the third diode is simultaneously connected to one end of the seventh resistor and the cathode of the third diode. One end of the eighth resistor is connected.

从上述描述可知,在主输出端断电后,通过第三二极管隔断充电电容的一条放电通道,以减缓充电电容的放电速度。As can be seen from the above description, after the main output end is powered off, a discharge channel of the charging capacitor is cut off by the third diode, so as to slow down the discharging speed of the charging capacitor.

进一步地,所述充电电容的稳态电压大于a+c且小于a+b+c,所述c为所述第三二极管的导通电压。Further, the steady-state voltage of the charging capacitor is greater than a+c and less than a+b+c, where c is the turn-on voltage of the third diode.

从上述描述可知,当增加第三二极管时,则需要考虑到二极管的导通电压,来使得第一三极管的状态变化。It can be seen from the above description that when the third diode is added, the on-voltage of the diode needs to be considered to change the state of the first transistor.

进一步地,所述充电电容的稳态电压大于a+0.4b+c且小于a+0.6b+c。Further, the steady-state voltage of the charging capacitor is greater than a+0.4b+c and less than a+0.6b+c.

从上述描述可知,当将充电电容的稳态电压大于a+0.4b+c且小于a+0.6b+c,可在短路故障时使得第一三极管快速导通。As can be seen from the above description, when the steady-state voltage of the charging capacitor is greater than a+0.4b+c and less than a+0.6b+c, the first triode can be quickly turned on in the event of a short-circuit fault.

进一步地,所述充电电容与所述第九电阻之间形成的放电常数在0.1秒至10秒之间。Further, the discharge constant formed between the charging capacitor and the ninth resistor is between 0.1 seconds and 10 seconds.

从上述描述可知,选择合理的充电电容和第九电阻进行配合,使得充电电容的放电速度较慢,以维持合理的打嗝时间,减少损耗。It can be seen from the above description that a reasonable charging capacitor is selected to cooperate with the ninth resistor, so that the discharging speed of the charging capacitor is slow, so as to maintain a reasonable hiccup time and reduce losses.

针对PWM输出控制端的连接位置的不同,提供以下两个实施例。The following two embodiments are provided for different connection positions of the PWM output control terminals.

请参照图1至图2,本发明的实施例一为:Please refer to FIG. 1 to FIG. 2 , the first embodiment of the present invention is:

多路输出电源的短路保护电路,即对应图1中的第一保护电路,其中,本实施例的第一保护电路与电源管理芯片U3连接,通过监测电源管理芯片U3的供电电压Vcc来实现对电路的保护。The short-circuit protection circuit of the multi-channel output power supply corresponds to the first protection circuit in FIG. 1, wherein the first protection circuit of this embodiment is connected to the power management chip U3, and the power supply voltage Vcc of the power management chip U3 is monitored to realize the protection. circuit protection.

如图2所示,第一保护电路包括第一三极管Q1、第二三极管Q2、第一电阻R1、第二电阻R2、第三电阻R3、充电电容C2、第一二极管D1、第四电阻R4、第五电阻R5和第六电阻R6;第一三极管Q1的基极通过第一电阻R1与多路输出电源的供电电压端连接,第一三极管Q1的集电极通过第二电阻R2与第二三极管Q2的基极连接且通过第三电阻R3与第二三极管Q2的发射极连接,第一三极管Q1的发射极同时与充电电容C2的一端、第五电阻R5的一端连接,充电电容C2的另一端接地且通过第六电阻R6与第一三极管Q1的基极连接,第五电阻R5的另一端与第一二极管D1的阴极连接,第一二极管D1的阳极与多路输出电源的电源管理芯片U3的基准电压端VREF连接;其中,第二三极管Q2的集电极通过第四电阻R4与多路输出电源的供电电压端连接且发射极接地;第一三极管Q1在多路输出电源的供电电压端受输出端短路影响而降低时由截止状态转换为导通状态。As shown in FIG. 2 , the first protection circuit includes a first transistor Q1, a second transistor Q2, a first resistor R1, a second resistor R2, a third resistor R3, a charging capacitor C2, and a first diode D1 , the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6; the base of the first transistor Q1 is connected to the supply voltage terminal of the multi-output power supply through the first resistor R1, and the collector of the first transistor Q1 The second resistor R2 is connected to the base of the second transistor Q2 and the third resistor R3 is connected to the emitter of the second transistor Q2. The emitter of the first transistor Q1 is connected to one end of the charging capacitor C2 at the same time. , One end of the fifth resistor R5 is connected, the other end of the charging capacitor C2 is grounded and connected to the base of the first transistor Q1 through the sixth resistor R6, and the other end of the fifth resistor R5 is connected to the cathode of the first diode D1 connected, the anode of the first diode D1 is connected to the reference voltage terminal VREF of the power management chip U3 of the multi-channel output power supply; wherein, the collector of the second transistor Q2 is connected to the power supply of the multi-channel output power supply through the fourth resistor R4 The voltage terminal is connected and the emitter is grounded; when the supply voltage terminal of the multi-channel output power supply is reduced by the short circuit of the output terminal, the first transistor Q1 is converted from the off state to the on state.

即在本实施例中,第一三极管Q1为PNP三极管,第二三极管Q2为NPN三极管,第一电压端和PWM输出控制端均为多路输出电源的供电电压端,即对应图2的供电电压Vcc;第二电压端为多路输出电源的电源管理芯片U3的基准电压端VREF。That is, in this embodiment, the first transistor Q1 is a PNP transistor, the second transistor Q2 is an NPN transistor, and the first voltage terminal and the PWM output control terminal are both the supply voltage terminals of the multi-channel output power supply, that is, the corresponding figure The power supply voltage Vcc of 2; the second voltage terminal is the reference voltage terminal VREF of the power management chip U3 of the multi-channel output power supply.

通过图2并结合上述描述可知,在上电瞬间,由输入直流高压Vin通过电阻R15-R17(200k/3W)给第一电容C1(100uF/50V)充电,达到电源启动电压,反激电源启动工作,在本实施例中,输入直流高压Vin为固定电压16V,多路输出电源的电源管理芯片U3(UC2845BD)的基准电压端VREF通过第一二极管D1(150mA/100V)、第五电阻R5(10k/0603)给充电电容C2(10uF/16V)充电,直到充电电容C2的两端电压为5V;同时,第一电阻R1(150k/0603)和第六电阻R6(75k/0603)设置的比例为2:1;此时第六电阻R6的两端电压为5.33V,第一三极管Q1(0.6A/-60V)处于截止状态。当任一输出端短路的时候,按照匝数比等效电压计算,供电电压Vcc会被拉低,但是由于各输出端存在漏感及等效阻抗等问题,不能保证所有输出短路时,供电电压Vcc都能拉低到欠电压保护点。这里以最差一路为例,当供电电压Vcc拉低到12V,在第六电阻R6的两端电压为4V,第一三极管Q1将会导通,此时第二三极管Q2(0.6A/60V)在充电电容C2的电压和第二电阻R2(5k/0603)的驱动下也将会导通,供电电压Vcc将会通过第四电阻R4(100Ω/0805)和第二三极管Q2对地迅速放电,其中,充电电容C2、第二电阻R2和第三电阻R3之间形成的放电常数大于第一电容C1和第四电阻R4之间形成的放电常数的10倍,使得充电电容C2的两端电压通过第一三极管Q1和第三电阻R3对地放电的速度要慢于供电电压Vcc通过第四电阻R4对地放电到电压触发电源管理芯片U3的驱动电压端VI的欠压保护点,以保证供电电压端的供电电压Vcc能触发电源管理芯片U3的驱动电压端VI的欠压保护点,从而切断PWM输出端OUTPUT的输出,以对多路输出电源进行有效的保护。According to Figure 2 and the above description, at the moment of power-on, the first capacitor C1 (100uF/50V) is charged by the input DC high voltage Vin through the resistors R15-R17 (200k/3W) to reach the starting voltage of the power supply, and the flyback power supply starts. In this embodiment, the input DC high voltage Vin is a fixed voltage of 16V, and the reference voltage terminal VREF of the power management chip U3 (UC2845BD) of the multi-channel output power supply passes through the first diode D1 (150mA/100V), the fifth resistor R5 (10k/0603) charges the charging capacitor C2 (10uF/16V) until the voltage across the charging capacitor C2 is 5V; at the same time, the first resistor R1 (150k/0603) and the sixth resistor R6 (75k/0603) are set The ratio is 2:1; at this time, the voltage across the sixth resistor R6 is 5.33V, and the first transistor Q1 (0.6A/-60V) is in an off state. When any output terminal is short-circuited, the power supply voltage Vcc will be pulled down according to the equivalent voltage of the turns ratio. However, due to the leakage inductance and equivalent impedance of each output terminal, it cannot be guaranteed that when all outputs are short-circuited, the power supply voltage Vcc can be pulled down to the undervoltage protection point. Take the worst route as an example, when the power supply voltage Vcc is pulled down to 12V, the voltage at both ends of the sixth resistor R6 is 4V, the first transistor Q1 will be turned on, and the second transistor Q2 (0.6 A/60V) will also be turned on under the drive of the voltage of the charging capacitor C2 and the second resistor R2 (5k/0603), and the supply voltage Vcc will pass through the fourth resistor R4 (100Ω/0805) and the second transistor Q2 is rapidly discharged to the ground, wherein the discharge constant formed between the charging capacitor C2, the second resistor R2 and the third resistor R3 is greater than 10 times the discharge constant formed between the first capacitor C1 and the fourth resistor R4, so that the charging capacitor The speed at which the voltage across C2 is discharged to ground through the first transistor Q1 and the third resistor R3 is slower than the discharge of the supply voltage Vcc to the ground through the fourth resistor R4 to the voltage-triggered power supply management chip U3 driving voltage terminal VI To ensure that the power supply voltage Vcc of the power supply voltage terminal can trigger the undervoltage protection point of the driving voltage terminal VI of the power management chip U3, thereby cutting off the output of the PWM output terminal OUTPUT to effectively protect the multi-channel output power supply.

在本实施例中,将第一电阻R1和第六电阻R6的阻值比为2,且充电电容C2的稳态电压为5V,供电电压Vcc在正常状态下为16V,载短路状态下为12V。而在其他等同实施例中,当第一电阻R1和第六电阻R6的阻值比为X时,充电电容C2的稳态电压小于多路输出电源在正常状态下的供电电压Vcc/(X+1)且大于多路输出电源在任何一路输出电源短路时的供电电压Vcc/(X+1)即可。In this embodiment, the resistance ratio of the first resistor R1 and the sixth resistor R6 is 2, the steady-state voltage of the charging capacitor C2 is 5V, the power supply voltage Vcc is 16V in a normal state, and 12V in a load short-circuit state . In other equivalent embodiments, when the resistance ratio of the first resistor R1 and the sixth resistor R6 is X, the steady-state voltage of the charging capacitor C2 is lower than the supply voltage Vcc/(X+ 1) and is greater than the power supply voltage Vcc/(X+1) of the multi-channel output power supply when any output power supply is short-circuited.

请参照图3至图4,本发明的实施例二为:Please refer to FIG. 3 to FIG. 4 , the second embodiment of the present invention is:

多路输出电源的短路保护电路,即对应图3中的第二保护电路,其中,本实施例的第二保护电路与光电耦合器U1连接,通过监测光电耦合器U1的输出端电压来实现对电路的保护。The short-circuit protection circuit of the multi-channel output power supply corresponds to the second protection circuit in FIG. 3 , wherein the second protection circuit of this embodiment is connected to the optocoupler U1, and the output terminal voltage of the optocoupler U1 is monitored to realize the protection. circuit protection.

如图4所示,第二保护电路包括第一三极管Q1、第二三极管Q2、第一电阻R9、第二电阻R2、第三电阻R3、充电电容C2、与多路输出电源的辅助供电支路的数量对应的第二二极管D2/D4、第七电阻R7、第八电阻R8和第三二极管D3;第一三极管Q1的基极与第一电阻R9的一端连接,第一电阻R9的另一端同时与多个第二二极管D2/D4的阳极连接,每一个第二二极管D2/D4的阴极分别与多路输出电源的一个辅助供电支路的支路输出端V1/V2连接;第一三极管Q1的集电极通过第二电阻R2与第二三极管Q2的基极连接且通过第三电阻R3与第二三极管Q2的发射极连接,第一三极管Q1的发射极同时与充电电容C2的一端、第三二极管D3的阴极连接,第三二极管D3的阳极同时与第七电阻R7的一端、第八电阻R8的一端连接,充电电容C2的另一端与第七电阻R7的另一端同时接地,第八电阻R8的另一端与多路输出电源的主输出端V3连接;第二三极管Q2的集电极与多路输出电源的光耦检测输出电压端连接且发射极接地;As shown in FIG. 4 , the second protection circuit includes a first transistor Q1, a second transistor Q2, a first resistor R9, a second resistor R2, a third resistor R3, a charging capacitor C2, and a multi-channel output power supply. The number of auxiliary power supply branches corresponds to the second diode D2/D4, the seventh resistor R7, the eighth resistor R8 and the third diode D3; the base of the first transistor Q1 and one end of the first resistor R9 connection, the other end of the first resistor R9 is connected to the anodes of a plurality of second diodes D2/D4 at the same time, and the cathodes of each second diode D2/D4 are respectively connected to an auxiliary power supply branch of an auxiliary power supply branch of the multi-channel output power supply. The branch output terminals V1/V2 are connected; the collector of the first transistor Q1 is connected to the base of the second transistor Q2 through the second resistor R2 and is connected to the emitter of the second transistor Q2 through the third resistor R3 connected, the emitter of the first transistor Q1 is simultaneously connected to one end of the charging capacitor C2 and the cathode of the third diode D3, and the anode of the third diode D3 is simultaneously connected to one end of the seventh resistor R7 and the eighth resistor R8 The other end of the charging capacitor C2 and the other end of the seventh resistor R7 are grounded at the same time, and the other end of the eighth resistor R8 is connected to the main output terminal V3 of the multi-output power supply; the collector of the second transistor Q2 is connected to The optocoupler detection output voltage terminal of the multi-channel output power supply is connected and the emitter is grounded;

即在本实施例中,第一三极管Q1为PNP三极管,第二三极管Q2为NPN三极管,PWM输出控制端为多路输出电源的光耦检测输出电压端,即图4中的光电耦合器U1的第四端;第一电压端为多路输出电源的一个辅助供电支路的支路输出端V1/V2;第二电压端为多路输出电源的主输出端V3。That is, in this embodiment, the first transistor Q1 is a PNP transistor, the second transistor Q2 is an NPN transistor, and the PWM output control terminal is the optocoupler detection output voltage terminal of the multi-channel output power supply, that is, the optoelectronic The fourth terminal of the coupler U1; the first voltage terminal is the branch output terminal V1/V2 of an auxiliary power supply branch of the multi-channel output power supply; the second voltage terminal is the main output terminal V3 of the multi-channel output power supply.

通过图4并结合上述描述可知,在本实施例中,假设多路输出电源的主输出端V3的正常电压为12V,多路输出电源的所有辅助供电支路的正常电压的最低值b为5V,比如图4中的支路输出端V2的正常电压为b=5V,支路输出端V1的正常电压为9V。第一三极管Q1(0.6A/-60V)上发射极和基极之间的导通电压a一般为0.7V,第三二极管D3(150mA/100V)的导通电压c一般为0.7V。It can be seen from FIG. 4 combined with the above description that in this embodiment, it is assumed that the normal voltage of the main output terminal V3 of the multi-output power supply is 12V, and the minimum value b of the normal voltage of all auxiliary power supply branches of the multi-output power supply is 5V For example, the normal voltage of the branch output terminal V2 in FIG. 4 is b=5V, and the normal voltage of the branch output terminal V1 is 9V. The turn-on voltage a between the emitter and the base of the first transistor Q1 (0.6A/-60V) is generally 0.7V, and the turn-on voltage c of the third diode D3 (150mA/100V) is generally 0.7 V.

此时,通过第八电阻R8(2k/0603)和第七电阻R7(1.5k/0603)分压,将充电电容C2的电压限定在6.4V以下,在其他实施例中,充电电容C2的电压高于a+c,即高于1.4V,实际可能设置在2V以上,以便两个辅助供电支路短路时,第一三极管Q1能导通。At this time, the voltage of the charging capacitor C2 is limited to be less than 6.4V by dividing the voltage by the eighth resistor R8 (2k/0603) and the seventh resistor R7 (1.5k/0603). In other embodiments, the voltage of the charging capacitor C2 Higher than a+c, that is, higher than 1.4V, it may actually be set above 2V, so that when the two auxiliary power supply branches are short-circuited, the first transistor Q1 can be turned on.

在正常情况下,第一三极管Q1的发射极电压低于基极电压,第一三极管Q1的集电极-发射极两端保持关段状态,第二三极管Q2(0.6A/60V)的集电极-发射极两端也保持关段状态,使得保护电路对光电耦合器U1不产生影响。Under normal circumstances, the emitter voltage of the first transistor Q1 is lower than the base voltage, the collector-emitter terminals of the first transistor Q1 remain in the off-segment state, and the second transistor Q2 (0.6A/ 60V) both ends of the collector-emitter also maintain the off-stage state, so that the protection circuit does not affect the optocoupler U1.

当辅助供电支路任何一个短路时,第二二极管D2(150mA/100V)或D4(150mA/100V)导通,第一三极管Q1的基极电压迅速下降,导致第一三极管Q1开通,第二三极管Q2的基极电压迅速上升后,第二三极管Q2导通,然后光电耦合器U1(K1010-4C-1)饱和导通,将原本的电源管理芯片U3(UC2845BD)的PWM输出端OUTPUT关段。随后主输出端V3的电压迅速下降,但充电电容C2(22uF/16V)对第二电阻R2(15k/0603)、第三电阻R3(100k/0603)、第一电阻R9(49.9k/0603)放电较慢,可以维持对第二三极管Q2的导通,因此辅电会关闭一段时间,其中,通过第三二极管D3隔断充电电容C2的一条放电通道,以减缓充电电容C2的放电速度。When any one of the auxiliary power supply branches is short-circuited, the second diode D2 (150mA/100V) or D4 (150mA/100V) is turned on, and the base voltage of the first transistor Q1 drops rapidly, resulting in the first transistor Q1. Q1 is turned on, after the base voltage of the second transistor Q2 rises rapidly, the second transistor Q2 is turned on, and then the photocoupler U1 (K1010-4C-1) is saturated and turned on, turning the original power management chip U3 ( The PWM output terminal OUTPUT of UC2845BD) is closed. Then the voltage of the main output terminal V3 drops rapidly, but the charging capacitor C2 (22uF/16V) has no effect on the second resistor R2 (15k/0603), the third resistor R3 (100k/0603), the first resistor R9 (49.9k/0603) The discharge is slow, and the conduction of the second transistor Q2 can be maintained, so the auxiliary power will be turned off for a period of time. Among them, a discharge channel of the charging capacitor C2 is blocked by the third diode D3 to slow down the charging capacitor C2 The discharge of speed.

而当充电电容C2的电压下降到无法使得第一三极管Q1导通时,比如下降到1V以下,辅电重启,如果多路输出电源的短路情况仍然存在,则会将充电电容C2充电至1.4V以上时,再次将电源管理芯片U3的PWM输出端OUTPUT关闭,电源再次进行进入重启状态,后续并反复重启,电源进入“打嗝”保护模式;When the voltage of the charging capacitor C2 drops to such an extent that the first transistor Q1 cannot be turned on, for example, it drops below 1V, the auxiliary power is restarted. If the short circuit of the multi-output power supply still exists, the charging capacitor C2 will be charged to When the voltage is above 1.4V, turn off the PWM output OUTPUT of the power management chip U3 again, the power supply will enter the restart state again, and then restart repeatedly, the power supply will enter the "hiccup" protection mode;

而当多路输出电源的短路情况已经消除的情况下,电源重启,充电电容C2的电压在第八电阻R8的限制下,逐渐充电至1.4V以上时,支路电压端V1和V2的电压已经上升,使得第一二极管D1和第二二极管D2/D4保持关段,辅电能正常启动并工作。When the short circuit of the multi-channel output power supply has been eliminated, the power supply is restarted, and the voltage of the charging capacitor C2 is gradually charged to more than 1.4V under the limit of the eighth resistor R8, and the voltages of the branch voltage terminals V1 and V2 have been rising, so that the first diode D1 and the second diode D2/D4 remain off, and the auxiliary power starts and works normally.

其中,在本实施例中,b=5V,a=c=0.7V,则充电电容的稳态电压进一步限制在大于3.4V至4.4之间,比如取3.9V左右,以保证第一三极管Q1在短路故障时能快速导通,从而快速实现对电路的保护。Among them, in this embodiment, b=5V, a=c=0.7V, then the steady-state voltage of the charging capacitor is further limited to be greater than 3.4V to 4.4, such as about 3.9V, to ensure that the first transistor Q1 can be quickly turned on in the event of a short-circuit fault, so as to quickly realize the protection of the circuit.

其中,在本实施例中,充电电容C2的容量为22uF,第一电阻R9、第二电阻R2和第三电阻R3的阻值分别为49.9k、15k和100k。在其他等同实施例中,充电电容C2的容量取值较大,第一电阻R9和第八电阻R8之间的电阻差别较大,由此,充电电容C2与第一电阻R9、第二电阻R2和第三电阻R3之间形成的放电常数在0.1秒至10秒之间(如0.25s左右),即在秒级,而此时,充电电容C2与第八电阻R8的充电常数则控制在数十毫秒(如50ms左右);如本实施例中第一电阻R9和第二电阻R2分别为49.9k和15k时,第八电阻R8取2k,第七电阻R7取1.5k。由此通过对充电电容C2以及第一电阻R9、第二电阻R2、第三电阻R3、第七电阻R7和第八电阻R8的合理选择,以减慢充电电容C2的放电速度,维持合理的打嗝时间,减少损耗;同时避免充电过快而造成辅电无法重启。Wherein, in this embodiment, the capacity of the charging capacitor C2 is 22uF, and the resistance values of the first resistor R9, the second resistor R2 and the third resistor R3 are 49.9k, 15k and 100k respectively. In other equivalent embodiments, the capacity of the charging capacitor C2 is larger, and the resistance difference between the first resistor R9 and the eighth resistor R8 is larger. Therefore, the charging capacitor C2 is different from the first resistor R9 and the second resistor R2. The discharge constant formed between the third resistor R3 and the third resistor R3 is between 0.1 seconds and 10 seconds (such as about 0.25s), that is, in the second level. At this time, the charging constant of the charging capacitor C2 and the eighth resistor R8 is controlled within a few seconds. Ten milliseconds (such as about 50ms); for example, when the first resistor R9 and the second resistor R2 are 49.9k and 15k respectively in this embodiment, the eighth resistor R8 is 2k, and the seventh resistor R7 is 1.5k. Therefore, through reasonable selection of the charging capacitor C2, the first resistor R9, the second resistor R2, the third resistor R3, the seventh resistor R7 and the eighth resistor R8, the discharge speed of the charging capacitor C2 can be slowed down and a reasonable hiccup can be maintained. Time, reduce loss; at the same time, avoid charging too fast and cause the auxiliary power to fail to restart.

其中,如图2所示,为了便于理解本发明,将图2中涉及到由电源管理芯片U3组成的PWM电路以及由光电耦合器U1和TL431器件U2组成的电压输出电路进行说明。Among them, as shown in FIG. 2, in order to facilitate understanding of the present invention, the PWM circuit composed of the power management chip U3 and the voltage output circuit composed of the optocoupler U1 and the TL431 device U2 in FIG. 2 are described.

其中,PWM电路包括电阻R10(10kΩ/0603)、电阻R11(470Ω/0603)、电容C3(1uF/0603)、二极管D5(150mA/150V)、二极管D6(150mA/150V)和电源管理芯片U3(UC2845BD),电源管理芯片U3的第一引脚分别与二极管D6的阳极和光电耦合器U1的第一端电连接,电源管理芯片U3的第八引脚分别与电阻R10的一端和二极管D5(的阴极电连接,二极管D5(的阳极分别与电阻R10的另一端、电容C3的一端和二极管D6的阴极电连接,电容C3的另一端与电阻R11的一端电连接且电容C3的另一端和电阻R11的一端均接地,电阻R11的另一端与光电耦合器U1的第二端电连接。当光电耦合器U1的第一端和第二端等效电阻较大时,电源管理芯片U3的第一引脚保持较高电平,使得电源管理芯片U3的第六引脚输出占空比较大的PWM控制信号,主输出端V3的电压持续上升;当主输出端V3的电压上升到预定值附近时,光电耦合器U1的第一端和第二端等效电阻变小,电源管理芯片U3的第一引脚电平下降,使得电源管理芯片U3的第六引脚输出的PWM信号的占空比变小,从而使主输出端V3的电压稳定在预设值。Among them, the PWM circuit includes resistor R10 (10kΩ/0603), resistor R11 (470Ω/0603), capacitor C3 (1uF/0603), diode D5 (150mA/150V), diode D6 (150mA/150V) and power management chip U3 ( UC2845BD), the first pin of the power management chip U3 is electrically connected to the anode of the diode D6 and the first end of the optocoupler U1 respectively, and the eighth pin of the power management chip U3 is respectively connected to one end of the resistor R10 and one end of the diode D5 ( The cathode is electrically connected, the anode of the diode D5 is electrically connected to the other end of the resistor R10, one end of the capacitor C3 and the cathode of the diode D6, the other end of the capacitor C3 is electrically connected to one end of the resistor R11, and the other end of the capacitor C3 is electrically connected to the resistor R11 One end of the resistor R11 is grounded, and the other end of the resistor R11 is electrically connected to the second end of the photocoupler U1. When the equivalent resistance of the first end and the second end of the photocoupler U1 is large, the first lead of the power management chip U3 The pin maintains a high level, so that the sixth pin of the power management chip U3 outputs a PWM control signal with a large duty ratio, and the voltage of the main output V3 continues to rise; when the voltage of the main output V3 rises to a predetermined value, the photoelectric The equivalent resistance of the first end and the second end of the coupler U1 becomes smaller, and the level of the first pin of the power management chip U3 decreases, so that the duty cycle of the PWM signal output by the sixth pin of the power management chip U3 becomes smaller , so that the voltage of the main output terminal V3 is stabilized at the preset value.

其中,电压输出电路包括光电耦合器U1、电阻R19(10kΩ/0603)、电阻R18(38kΩ/0603)、电阻R12(10kΩ/0603)、电阻R14(1kΩ/1206)、电阻R13(100kΩ/0603)、电容C4(220pF/0603)、电容C5(0.1uF/0603)和TL431器件U2(TL431/SOT-89),TL431器件U2的第一引脚与电阻R19的一端电连接且TL431器件U2的第一引脚和电阻R19的一端均接地,TL431器件U2的第二引脚分别与电阻R19的另一端、电阻R18的一端、电容C4的一端和电容C5的一端电连接,电容C5的另一端与电阻R13的一端电连接,电阻R13的另一端分别与电容C4的另一端、电阻R12的一端、TL431器件U2的第三引脚、第二三极管Q2的集电极和光电耦合器U1的第四端电连接,电阻R18的另一端分别与电阻R12的另一端、电阻R14的一端和主输出端V3电连接,电阻R14的另一端与光电耦合器U1的第三端电连接。当电源启动后,主输出端V3的电压上升至预定值之前,TL431器件U2的第二引脚电压通过电阻R18和R19的分压小于2.5V,U2的第二引脚输出较高电压,使得光电耦合器U1的第三端和第四端间的电流很小,光电耦合器U1的第一端和第二端保持较高的等效电阻;当主输出端V3上升至预定值时,TL431器件U2的第二引脚电压通过电阻R18和R19的分压接近2.5V,U2的第二引脚输出电压降低,使得光电耦合器U1的第三端和第四端间的电流很变大,光电耦合器U1的第一端和第二端等效电阻变小。Among them, the voltage output circuit includes photocoupler U1, resistor R19 (10kΩ/0603), resistor R18 (38kΩ/0603), resistor R12 (10kΩ/0603), resistor R14 (1kΩ/1206), resistor R13 (100kΩ/0603) , capacitor C4 (220pF/0603), capacitor C5 (0.1uF/0603) and TL431 device U2 (TL431/SOT-89), the first pin of TL431 device U2 is electrically connected to one end of resistor R19 and the first pin of TL431 device U2 A pin and one end of the resistor R19 are both grounded, the second pin of the TL431 device U2 is electrically connected to the other end of the resistor R19, one end of the resistor R18, one end of the capacitor C4 and one end of the capacitor C5, and the other end of the capacitor C5 is electrically connected to One end of the resistor R13 is electrically connected, and the other end of the resistor R13 is respectively connected with the other end of the capacitor C4, one end of the resistor R12, the third pin of the TL431 device U2, the collector of the second transistor Q2 and the third pin of the photocoupler U1. The four terminals are electrically connected, the other end of the resistor R18 is electrically connected to the other end of the resistor R12, one end of the resistor R14 and the main output terminal V3, and the other end of the resistor R14 is electrically connected to the third terminal of the photocoupler U1. When the power is turned on, before the voltage of the main output terminal V3 rises to a predetermined value, the voltage of the second pin of the TL431 device U2 is less than 2.5V through the voltage division of the resistors R18 and R19, and the second pin of U2 outputs a higher voltage, so that The current between the third terminal and the fourth terminal of the optocoupler U1 is very small, and the first and second terminals of the optocoupler U1 maintain a high equivalent resistance; when the main output terminal V3 rises to a predetermined value, the TL431 device The voltage of the second pin of U2 is close to 2.5V through the voltage division of the resistors R18 and R19, and the output voltage of the second pin of U2 decreases, so that the current between the third and fourth ends of the optocoupler U1 becomes larger, and the photoelectric The equivalent resistance of the first end and the second end of the coupler U1 becomes smaller.

综上所述,本发明提供的多路输出电源的短路保护电路,在多路输出电源正常工作时,由多路输出电源的第二电压端对充电电容进行充电,直到达到稳定电压;当多路输出电源的任一输出端短路的时候,多路输出电源的第一电压端发生变化,使得第一三极管由截止状态转换为导通状态,此时,由于第一三极管为PNP三极管,因此,与第一三极管的发射极连接的充电电容开始放电,在充电电容的电压和第三电阻的驱动下,第二二极管开始导通,使得与第二三极管的集电极连接的多路输出电源的PWM输出控制端开始对地放电,以使得PWM输出控制端的电压开始下降,从而切断PWM输出端的输出,以对多路输出电源进行有效的保护。即本发明通过低成本搭建电路,解决了变压器各绕组间漏感以及等效电阻等不同因数对输出短路的影响,从而在多路输出电源的任一输出端短路的时候,都能对多路输出电源进行有效的保护。其中,提供了供电电压检测保护电路的实施例一和输出电压检测保护电路的实施例二。对于实施例一来说,通过选取合适的充电电容、第一电阻、第六电阻、第三电阻、第四电阻来保证其保护效果。对于实施例二来说,选择合理的充电电容、第一电阻、第二电阻、第三电阻、第七电阻和第八电阻,使得充电电容的放电速度较慢,以维持合理的打嗝时间,减少损耗;同时避免充电过快所导致辅电无法重启的问题;另外,在主输出端断电后,通过第三二极管隔断充电电容的一条放电通道,以减缓充电电容的放电速度。To sum up, in the short-circuit protection circuit of the multi-channel output power supply provided by the present invention, when the multi-channel output power supply works normally, the charging capacitor is charged by the second voltage terminal of the multi-channel output power supply until a stable voltage is reached; When any output terminal of the multiple output power supply is short-circuited, the first voltage terminal of the multiple output power supply changes, so that the first transistor is converted from the off state to the on state. At this time, since the first transistor is a PNP Therefore, the charging capacitor connected to the emitter of the first triode begins to discharge, and driven by the voltage of the charging capacitor and the third resistor, the second diode begins to conduct, so that the second diode is connected to the second triode. The PWM output control terminal of the multi-output power supply connected to the collector starts to discharge to the ground, so that the voltage of the PWM output control terminal starts to drop, thereby cutting off the output of the PWM output terminal, so as to effectively protect the multi-output power supply. That is, the present invention solves the influence of different factors such as leakage inductance and equivalent resistance between the transformer windings on the output short circuit by building a circuit at low cost, so that when any output end of the multi-channel output power supply is short-circuited, the multi-channel output power supply can be short-circuited. The output power is effectively protected. Among them, the first embodiment of the power supply voltage detection protection circuit and the second embodiment of the output voltage detection protection circuit are provided. For the first embodiment, the protection effect is ensured by selecting appropriate charging capacitors, first resistors, sixth resistors, third resistors, and fourth resistors. For the second embodiment, reasonable charging capacitors, first resistors, second resistors, third resistors, seventh resistors and eighth resistors are selected to make the discharge speed of the charging capacitors slower, so as to maintain a reasonable hiccup time and reduce At the same time, it avoids the problem that the auxiliary power cannot be restarted due to too fast charging; in addition, after the main output is powered off, a discharge channel of the charging capacitor is cut off by a third diode to slow down the discharging speed of the charging capacitor.

以上所述仅为本发明的实施例,并非因此限制本发明的专利范围,凡是利用本发明说明书及附图内容所作的等同变换,或直接或间接运用在相关的技术领域,均同理包括在本发明的专利保护范围内。The above descriptions are only examples of the present invention, and are not intended to limit the scope of the present invention. Any equivalent transformations made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in related technical fields, are similarly included in the within the scope of patent protection of the present invention.

Claims (10)

1. Short-circuit protection circuit of multiplexed output power supply, its characterized in that: the circuit comprises a first triode, a second triode, a first resistor, a second resistor, a third resistor and a charging capacitor;
the base electrode of the first triode is connected with the first voltage end of the multi-path output power supply through the first resistor, the collector electrode of the first triode is connected with the base electrode of the second triode through the second resistor and is connected with the emitter electrode of the second triode through the third resistor, the emitter electrode of the first triode is grounded through the charging capacitor, and the charging capacitor is connected with the second voltage end of the multi-path output power supply;
the collector of the second triode is connected with the PWM output control end of the multi-path output power supply, and the emitter of the second triode is grounded;
the first triode is a PNP triode and the second triode is an NPN triode;
and the first triode and the second triode are switched from a cut-off state to a conducting state when the first voltage end of the multi-path output power supply is reduced due to the influence of short circuit of the output end.
2. The short-circuit protection circuit of a multi-output power supply according to claim 1, wherein: the first voltage end and the PWM output control end are both power supply voltage ends of the multi-path output power supply;
the fourth resistor is connected between the collector of the second triode and the power supply voltage end of the multi-path output power supply;
the emitting electrode of the first triode is grounded through the charging capacitor, and the connection of the charging capacitor and the second voltage end of the multi-path output power supply specifically comprises the following steps:
an emitting electrode of the first triode is simultaneously connected with one end of the charging capacitor and one end of the fifth resistor, the other end of the charging capacitor is grounded and is connected with a base electrode of the first triode through the sixth resistor, the other end of the fifth resistor is connected with a cathode of the first diode, and an anode of the first diode is connected with a reference voltage end of a power management chip of the multi-output power supply;
the steady state voltage of the charging capacitor is smaller than the voltage of the sixth resistor at two ends of the multi-path output power supply in a normal state and is larger than the voltage of the sixth resistor at two ends of the output end of the multi-path output power supply in a short circuit state.
3. The short-circuit protection circuit of a multi-output power supply according to claim 2, wherein: the resistance ratio of the first resistor to the sixth resistor is X, and the steady-state voltage of the charging capacitor is smaller than the power supply voltage/(X +1) of the multi-path output power supply in a normal state and larger than the power supply voltage/(X +1) of the multi-path output power supply when any one path of output power supply is short-circuited.
4. The short-circuit protection circuit of a multi-output power supply according to claim 2, wherein: the power supply voltage end of the multi-path output power supply is further connected with a first capacitor, and a discharge constant formed among the charging capacitor, the second resistor and the third resistor is 10 times larger than a discharge constant formed among the first capacitor and the fourth resistor.
5. The short-circuit protection circuit of a multi-output power supply according to claim 1, wherein: the PWM output control end is an optical coupler detection output voltage end of the multi-path output power supply;
the base electrode of the first triode is connected with the first voltage end of the multi-path output power supply through the first resistor, and the connection specifically comprises the following steps:
the base electrode of the first triode is connected with one end of a first resistor, the other end of the first resistor is simultaneously connected with the anodes of a plurality of second diodes, and the cathode of each second diode is respectively connected with the branch output end of an auxiliary power supply branch of the multi-path output power supply;
the emitting electrode of the first triode is grounded through the charging capacitor, and the connection of the charging capacitor and the second voltage end of the multi-path output power supply specifically comprises the following steps:
an emitting electrode of the first triode is simultaneously connected with one end of the charging capacitor, one end of the seventh resistor and one end of the eighth resistor, the other end of the charging capacitor and the other end of the seventh resistor are simultaneously grounded, and the other end of the eighth resistor is connected with a main output end of the multi-path output power supply;
the steady state voltage of the charging capacitor is greater than a and less than a + b, wherein a is the conduction voltage between the emitter and the base of the first triode, and b is the lowest value of the normal voltage of all auxiliary power supply branches of the multi-output power supply.
6. The short-circuit protection circuit of a multi-output power supply according to claim 5, wherein: the ninth resistance is greater than the eighth resistance.
7. The short-circuit protection circuit of a multi-output power supply according to claim 5, wherein: still include the third diode, the projecting pole of first triode simultaneously with charge capacitor's one end, the one end of seventh resistance, the one end of eighth resistance is connected specifically:
and an emitting electrode of the first triode is simultaneously connected with one end of the charging capacitor and a cathode of the third diode, and an anode of the third diode is simultaneously connected with one end of the seventh resistor and one end of the eighth resistor.
8. The short-circuit protection circuit of a multi-output power supply according to claim 7, wherein: the steady-state voltage of the charging capacitor is greater than a + c and less than a + b + c, and c is the conduction voltage of the third diode.
9. The short-circuit protection circuit of a multi-output power supply of claim 8, wherein: the steady state voltage of the charging capacitor is greater than a +0.4b + c and less than a +0.6b + c.
10. The short-circuit protection circuit of a multiple-output power supply according to any one of claims 1 to 9, characterized in that: the discharge constant formed between the charging capacitor and the ninth resistor is between 0.1 second and 10 seconds.
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