CN108258655B - Protection circuit suitable for switching type power supply device with multiple outputs - Google Patents

Protection circuit suitable for switching type power supply device with multiple outputs Download PDF

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Publication number
CN108258655B
CN108258655B CN201611270665.XA CN201611270665A CN108258655B CN 108258655 B CN108258655 B CN 108258655B CN 201611270665 A CN201611270665 A CN 201611270665A CN 108258655 B CN108258655 B CN 108258655B
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coupled
terminal
signal
voltage
diode
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CN108258655A (en
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苏肖
石开源
杨军
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Asia Source Technology (shenzhen) Co Ltd
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Asia Source Technology (shenzhen) 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
    • H02H7/1203Circuits independent of the type of conversion
    • H02H7/1206Circuits independent of the type of conversion specially adapted to conversion cells composed of a plurality of parallel or serial connected elements

Abstract

A protection circuit is suitable for a switching power supply device with multiple outputs. The protection circuit includes a voltage abnormality detection unit and a protection trigger signal generation unit. The voltage abnormality detection unit is used for judging whether a first output voltage and a second output voltage of the switching type power supply device are respectively greater than a first default value and a second default value, and when any judgment result is yes, a coupling signal is generated. The protection trigger signal generating unit is used for generating and latching a protection trigger signal according to the coupling signal, and providing the protection trigger signal to a first pulse width modulation control circuit and a second pulse width modulation control circuit of the switching type power supply device, so as to control the first pulse width modulation control circuit and the second pulse width modulation control circuit to stop outputting a first pulse width modulation signal and a second pulse width modulation signal respectively.

Description

Protection circuit suitable for switching type power supply device with multiple outputs
Technical Field
The present invention relates to a power supply device, and more particularly, to a protection circuit for a switching power supply device with multiple outputs.
Background
The switching power supply device with multiple outputs can provide output voltages with different magnitudes to different electronic devices, so that the switching power supply device is popular among consumers. The switching power supply device may have an overvoltage condition at an output terminal thereof due to a failure of an internal feedback circuit thereof, thereby causing damage to internal components of the switching power supply device. In addition, the consumer may also accidentally short-circuit any two output terminals of the switching power supply device during the operation process, thereby causing damage to the internal components of the switching power supply device.
However, no protection circuit for a switching power supply device has been provided so far, which can protect the output terminal of the switching power supply device from both over-voltage and short-circuit.
Disclosure of Invention
The present invention provides a protection circuit suitable for a switching power supply device with multiple outputs, which can protect the output terminal of the switching power supply device from both over-voltage and short circuit.
The invention provides a protection circuit which is suitable for a switching type power supply device with multiple outputs. The protection circuit includes a voltage abnormality detection unit and a protection trigger signal generation unit. The voltage abnormality detection unit receives the first output voltage and the second output voltage of the switching power supply device, judges whether the first output voltage is greater than a first default value or not, judges whether the second output voltage is greater than a second default value or not, and generates a coupling signal when any one of the judgment results is yes. The protection trigger signal generating unit is used for generating and latching a protection trigger signal according to the coupling signal, and providing the protection trigger signal to a first pulse width modulation control circuit and a second pulse width modulation control circuit of the switching type power supply device, so as to control the first pulse width modulation control circuit and the second pulse width modulation control circuit to stop outputting a first pulse width modulation signal and a second pulse width modulation signal respectively.
In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a circuit diagram according to an embodiment of the invention.
Detailed Description
Referring to fig. 1, a reference numeral 100 denotes a switching power supply device with multiple outputs, and a combination of two parts shown in reference numerals 200 and 300 denotes a protection circuit according to an embodiment of the invention. For simplicity, the switching power supply 100 has two different outputs, and provides output voltages VOUT1 and VOUT2 through output terminals 100-1 and 100-2, respectively. As shown in fig. 1, the switching power supply apparatus 100 includes a noise filter 102, an ac-dc conversion circuit 104, a transformer 106, a power stage 108, an impedance 110, a rectification circuit 112, an energy storage unit 114, a rectification circuit 116, an energy storage unit 118, a feedback circuit 120, a signal isolation unit 122, a transformer 124, a power stage 126, an impedance 128, a rectification circuit 130, and an energy storage unit 132.
In this example, the transformer 106 has two primary windings (denoted by 106-1 and 106-2) and one secondary winding (denoted by 106-3), and one end of one primary winding 106-1 of the transformer 106 is coupled to the input voltage VIN through the ac-dc conversion circuit 104 and the noise filter 102 in sequence. The noise filter 102 may be an electromagnetic interference filter, and the designer may determine whether to use the noise filter 102 according to the actual design requirement. In addition, the ac-dc conversion circuit 104 may be a bridge rectifier.
The power stage 108 has a Pulse Width Modulation (PWM) control circuit 108-1 and a power transistor 108-2 as a switch therein. The power transistor 108-2 is coupled to the ac-dc conversion circuit 104 through the primary winding 106-1 and coupled to the reference voltage VSS1 through the impedance 110. By controlling the on/off state of the power transistor 108-2, it can be determined whether to allow current to pass through the primary winding 106-1. The PWM control circuit 108-1 receives the operating voltage VCC and generates a PWM signal to the control terminal of the power transistor 108-2, so as to control the switching frequency of the power transistor 108-2 between the on and off states. Of course, the power transistor 108-2 can be coupled between the primary winding 106-1 and the ac-dc converter circuit 104 instead, which is a simple replacement in the art.
One end of the other primary winding 106-2 of the transformer 106 is coupled to one end of the energy storage unit 118 through the rectifying circuit 116, and the other end of the primary winding 106-2 is coupled to the other end of the energy storage unit 118 and the reference potential VSS 1. The coupling of the rectifying circuit 116 and the energy storage unit 118 is the required operating voltage VCC of the whole system. One end of the secondary winding 106-3 of the transformer 106 is coupled to one end of the energy storage unit 114 through the rectifying circuit 112, and the other end of the secondary winding 106-3 is coupled to the other end of the energy storage unit 114 and a reference potential VSS2, wherein the reference potential VSS2 may be a ground potential. The output voltage VOUT1 can be generated at the coupling of the rectifying circuit 112 and the energy storage unit 114.
In this example, the rectifying circuits 112 and 116 may be implemented by a diode, and the rectifying circuit 112 may be coupled between the other end of the secondary winding 106-3 and the reference potential VSS2, and the rectifying circuit 116 may be coupled between the other end of the primary winding 106-2 and the reference potential VSS1, which is a simple replacement of the prior art, but the anodes of the two diodes of the rectifying circuits 112 and 116 are coupled to the reference potentials VSS2 and VSS1, respectively. In addition, the impedance 110 may be implemented by a resistor, the energy storage units 114 and 118 may be implemented by capacitors, and a designer may determine whether to use the impedance 110, the energy storage unit 114 and the energy storage unit 118 according to actual design requirements.
The signal isolation unit 122 may be an optical coupler, which is used to transmit the feedback signal generated by the feedback circuit 120 to the PWM control circuit 108-1, so that the PWM control circuit 108-1 can adjust the duty cycle of the PWM signal accordingly, and further, the value of the output voltage VOUT1 can be stabilized within a predetermined range.
The transformer 124 has a primary winding and a secondary winding (denoted by 124-1 and 124-2), and one end of the primary winding 124-1 of the transformer 124 is coupled to the input voltage VIN through the ac-dc conversion circuit 104 and the noise filter 102 in sequence. The power stage 126 has a PWM control circuit 126-1 and a power transistor 126-2 as a switch therein. The power transistor 126-2 is coupled to the ac-dc conversion circuit 104 through the primary winding 124-1 and coupled to the reference voltage VSS1 through the impedance 128. Whether to allow current to pass through the primary winding 124-1 can be determined by controlling the on/off state of the power transistor 126-2. The PWM control circuit 126-1 receives the operating voltage VCC and generates a PWM signal to the control terminal of the power transistor 126-2, so as to control the switching frequency of the power transistor 126-2 between the on state and the off state. Of course, the power transistor 126-2 may be coupled between the primary winding 124-1 and the ac-dc converter circuit 104 instead, which is a simple replacement of the prior art.
One end of the secondary winding 124-2 of the transformer 124 is coupled to one end of the energy storage unit 132 through the rectifying circuit 130, and the other end of the secondary winding 124-2 is coupled to the other end of the energy storage unit 132 and the reference potential VSS 2. The output voltage VOUT2 is generated at the coupling of the rectifying circuit 130 and the energy storage unit 132.
In this case, the rectifying circuit 130 can be implemented by a diode, and the rectifying circuit 130 can be modified to be coupled between the other end of the secondary coil 124-2 and the reference voltage VSS2, which is a simple replacement of the prior art, but the anode of the diode of the rectifying circuit 130 is coupled to the reference voltage VSS 2. In addition, the impedance 128 and the energy storage unit 132 can be implemented by a resistor and a capacitor, respectively, and a designer can determine whether to use the impedance 128 and the energy storage unit 132 according to actual design requirements.
The signal isolation unit 136 may also be an optical coupler, which can transmit the feedback signal generated by the feedback circuit 134 to the PWM control circuit 126-1, so that the PWM control circuit 126-1 can adjust the duty cycle of the PWM signal accordingly, and further, the value of the output voltage VOUT2 can be stabilized within a predetermined range.
Referring to fig. 1 again, the protection circuit includes a voltage abnormality detection unit 200 and a protection trigger signal generation unit 300. The voltage abnormality detection unit 200 receives the output voltages VOUT1 and VOUT2, determines whether the output voltage VOUT1 is greater than a first predetermined value, and determines whether the output voltage VOUT2 is greater than a second predetermined value, and generates a coupling signal if any of the above determination results is positive. The protection trigger signal generating unit 300 is used for generating and latching the protection trigger signal TRI according to the coupling signal, and providing the protection trigger signal TRI to the PWM control circuits 108-1 and 126-1, so as to control the two PWM control circuits to stop outputting the PWM signals respectively.
In the case that the switching power supply 100 has only two different outputs, the voltage abnormality detecting unit 200 includes a diode 202, an impedance 204, a signal transmitting unit 206, an impedance 208, a voltage-controlled switch 210, a zener diode 212, an impedance 214, an impedance 216, a diode 218, an impedance 220, and an impedance 222. The signal transmitting unit 206 has a first terminal 206-1 and a second terminal 206-2, and when the first terminal 206-1 and the second terminal 206-2 are turned on, the signal transmitting unit 206 generates the coupling signal. The signal transmission unit 206 can be a light emitting portion of an optical coupler. The voltage-controlled switch 210 has a first terminal 210-1, a second terminal 210-2 and a reference terminal 210-3, wherein the first terminal 210-1 of the voltage-controlled switch 210 is coupled to the second terminal 206-2 of the signal transmitting unit 206, and the second terminal 210-2 of the voltage-controlled switch 210 is coupled to the reference voltage VSS 2. When the voltage at the reference terminal 210-3 of the voltage-controlled switch 210 reaches a third predetermined value, the voltage-controlled switch 210-3 makes the first terminal 210-1 and the second terminal 210-2 form a conducting state. The voltage controlled switch 210-3 may be a switching component of TL 431.
The anode of the diode 202 may receive the output voltage VOUT1, the impedance 204 is coupled between the cathode of the diode 202 and the first terminal 206-1 of the signal transmitting unit 206, and the impedance 208 is connected in parallel with the signal transmitting unit 206. The zener diode 212 has a cathode coupled to the cathode of the diode 202, and an anode coupled to the reference terminal 210-3 of the voltage-controlled switch 210 through the impedance 214, and further coupled to the reference voltage VSS2 through the impedances 214 and 216 in sequence. The cathode of the diode 218 is coupled to the first terminal 206-1 of the signal transmitting unit 206, and the anode thereof receives the output voltage VOUT2 through the impedance 220. The impedance 222 is coupled between the output voltage VOUT2 and the reference terminal 210-3 of the voltage controlled switch 210.
In addition, under the condition that the switching power supply 100 has three different outputs, the voltage abnormality detecting unit 200 further includes a diode 224, an impedance 226, a zener diode 228 and an impedance 230. The anode of the diode 224 is used to receive the output voltage VOUT3 of the switching power supply 100, and the cathode is coupled to the cathode of the zener diode 228 through the impedance 226. The anode of the zener diode 228 is coupled to the reference terminal 210-3 of the voltage controlled switch 210 through the impedance 230. In this way, the voltage abnormality detecting unit 200 may further determine whether the output voltage VOUT3 is greater than a fourth predetermined value, and when the determination is yes, the coupling signal is generated. In addition, if the switching power supply 100 has more than three different outputs, the designer may use one more circuit indicated by the label 232 in the voltage abnormality detecting unit 200 for each output increase. If the switching power supply 100 has N different outputs, the designer can use the circuit shown by the N-2 set of labels 232 in the voltage abnormality detecting unit 200. In addition, in the voltage abnormality detecting unit 200, the impedances 204, 208, 214, 216, 220, 222, 226 and 230 can be implemented by using a resistor, and a designer can determine whether to use the impedances 204, 208, 220 and 226 according to actual design requirements.
The protection trigger signal generating unit 300 includes an impedance 302, a signal receiving unit 304, an impedance 306, an impedance 308, a PNP bipolar junction transistor 310, an impedance 312, an impedance 314, an NPN bipolar junction transistor 316, and a diode 318. The signal receiving unit 304 has a first terminal 304-1 and a second terminal 304-2, and when the signal receiving unit 304 receives the coupling signal, the first terminal 304-1 and the second terminal 304-2 are turned on. The signal receiving unit 304 can be implemented by using the same light receiving part of the optical coupler as the signal transmitting unit 206. The first terminal 304-1 of the signal receiving unit 304 receives the operating voltage VCC through the impedance 302, and the second terminal 304-2 of the signal receiving unit 304 is coupled to the reference voltage VSS1 through the impedance 306. The emitter E of the PNP type BJT 310 receives the operation voltage VCC through the impedance 308, and the collector C of the PNP type BJT 310 is coupled to the second terminal 304-2 of the signal receiving unit 304 through the impedance 312. The base B of the NPN BJT 316 is coupled to the second terminal 304-2 of the signal receiving unit 304 and coupled to the reference voltage VSS1 through the impedance 306. The collector C of the NPN BJT 316 is coupled to the base B of the PNP BJT 310 through a resistor 314, and the emitter E of the NPN BJT 316 is coupled to a reference voltage VSS 1. The diode 318 has a cathode coupled to the collector C of the NPN-type bjt 316 and an anode coupled to the PWM control circuit 108-1 and the PWM control circuit 126-1 for outputting the protection trigger signal TRI. In addition, in the protection trigger signal generating unit 300, the impedances 302, 306, 308, 312 and 314 can be implemented by using a resistor, and a designer can determine whether to use the impedances 302, 308, 312 and 314 according to the actual design requirement. Of course, the diode 318 may be replaced by another two diodes, but the cathodes of the two diodes are both coupled to the collector C of the NPN bjt 316, and the anodes of the two diodes are coupled to the PWM control circuit 108-1 and the PWM control circuit 126-1, respectively.
The following describes the operation of the protection circuit under different conditions according to various problems faced by consumers during operation. It should be noted that, in the following description, the output voltage VOUT1 has the largest value, the output voltage VOUT2 has the smallest value, and the remaining output voltages have values between the output voltages VOUT1 and VOUT 2.
Assuming that the switching power supply 100 is turned on and the output terminal 100-1 thereof is over-voltage, when the output voltage VOUT1 continuously rises to reach the first predetermined value, the zener diode 212 is turned on due to breakdown, and the divided voltage generated by the impedances 214 and 216 reaches the third predetermined value, for example, 2.5 volts (V), the voltage-controlled switch 210-3 turns on the first terminal 210-1 and the second terminal 210-2. In this way, the first terminal 206-1 and the second terminal 206-2 of the signal transmitting unit 206 are also turned on, so that the signal transmitting unit 206 generates the coupling signal. When the signal receiving unit 304 receives the coupling signal, the first terminal 304-1 and the second terminal 304-2 are turned on, and the NPN bjt 316 is turned on due to the base B thereof being pulled up to a high level. After the NPN bjt 316 is turned on, the PNP bjt 310 is also turned on because the base B thereof is pulled down to a low level, so that the base B of the NPN bjt 316 is continuously maintained at a high level. As a result, the NPN bjt 316 and the PNP bjt 310 are both turned on to generate an interlock effect, and the cathode of the diode 318 is continuously pulled down to a low level, which is equivalent to retaining the over-voltage information. Therefore, once the diode 318 is turned on, the diode 318 generates the protection trigger signal TRI from the anode thereof to trigger the PWM control circuit 108-1 and the PWM control circuit 126-1 to start performing the over-voltage protection function, i.e. to stop outputting the PWM signals respectively, so that the switching power supply device 100 stops providing the output voltages VOUT1 and VOUT 2.
Similarly, if the output terminal 100-2 is over-voltage, when the output voltage VOUT2 continuously rises to reach the second predetermined value and the divided voltage generated by the impedances 222 and 216 reaches the third predetermined value, the signal transmitting unit 206 also generates the coupling signal, so that the protection trigger signal generating unit 300 generates the protection trigger signal TRI. For another example, when the output voltage VOUT3 continuously rises to reach the fourth default value, so that the zener diode 228 is turned on due to breakdown, and further the divided voltage generated by the impedances 230 and 216 reaches the third default value, the signal transmitting unit 206 also generates the coupling signal, so that the protection trigger signal generating unit 300 generates the protection trigger signal TRI.
In addition, if the feedback circuit 120 or the signal isolation unit 122 in the switching power supply 100 is damaged and the consumer does not know that the switching power supply 100 is powered on, if the power on speed of the PWM control circuit 108-1 is faster than the power on speed of the PWM control circuit 126-1 (because the power on time of the two circuits is difficult to keep consistent), the output voltage VOUT1 will be generated first and will rise continuously to reach the first default value, so that the zener diode 212 is turned on due to breakdown, and the divided voltage generated by the impedances 214 and 216 reaches the third default value. In this way, the signal transmitting unit 206 also generates the coupling signal, so that the protection trigger signal generating unit 300 generates the protection trigger signal TRI, and the PWM control circuit 108-1 stops outputting the PWM signal. Since the cathode of the diode 318 is continuously pulled down to a low level due to the interlocking effect of the NPN bjt 316 and the PNP bjt 310, once the PWM control circuit 126-1 is turned on, the PWM control circuit 126-1 also receives the protection trigger signal TRI and stops outputting the PWM signal.
Similarly, if the feedback circuit 134 or the signal isolation unit 136 in the switching power supply 100 is damaged and the consumer unknowingly turns on the switching power supply 100, if the PWM control circuit 126-1 is turned on faster than the PWM control circuit 108-1, the output voltage VOUT2 will be generated first and will continuously rise to reach the second default value, so that the divided voltage generated by the impedances 222 and 216 reaches the third default value. In this way, the signal transmitting unit 206 also generates the coupling signal, so that the protection trigger signal generating unit 300 generates the protection trigger signal TRI, and the PWM control circuit 126-1 stops outputting the PWM signal. Since the interlocking effect of the NPN bjt 316 and the PNP bjt 310 causes the level of the cathode of the diode 318 to be continuously pulled down to a low level, once the PWM control circuit 108-1 is turned on, the PWM control circuit 108-1 also receives the protection trigger signal TRI and stops outputting the PWM signal.
In addition, if the consumer turns on the switching power supply 100, but inadvertently shorts the output terminals 100-1 and 100-2 of the switching power supply 100 after turning on, the output voltage VOUT2 will continuously rise to reach the second predetermined value, so that the divided voltage generated by the impedances 222 and 216 reaches the third predetermined value. In this way, the signal transmitting unit 206 also generates the coupling signal, so that the protection trigger signal generating unit 300 generates the protection trigger signal TRI, and the PWM control circuits 108-1 and 126-1 stop outputting the PWM signal.
In addition, if the output terminals 100-1 and 100-2 of the switching power supply 100 are inadvertently shorted by the consumer and the switching power supply 100 is unknowingly turned on, the output voltage VOUT1 is generated first if the PWM control circuit 108-1 is turned on faster than the PWM control circuit 126-1. The voltage division generated by the impedances 222 and 216 will quickly reach the third default value due to the short circuit of the output terminals 100-1 and 100-2. In this way, the signal transmitting unit 206 also generates the coupling signal, so that the protection trigger signal generating unit 300 generates the protection trigger signal TRI, and the PWM control circuit 108-1 stops outputting the PWM signal. Since the cathode of the diode 318 is continuously pulled down to a low level due to the interlocking effect of the NPN bjt 316 and the PNP bjt 310, once the PWM control circuit 126-1 is turned on, the PWM control circuit 126-1 also receives the protection trigger signal TRI and stops outputting the PWM signal.
In summary, since the voltage anomaly detection unit is utilized to determine whether any output voltage of the switching power supply device exceeds the corresponding default value, no matter whether the output terminal of the switching power supply device presents an overvoltage due to the failure of the feedback circuit or the signal isolation unit or presents an overvoltage due to a short circuit, when any determination result is yes, the voltage anomaly detection unit generates the coupling signal to control the protection trigger signal generation unit to generate and latch the protection trigger signal, so that the pwm control circuit is controlled to stop outputting the pwm signal, thereby achieving the purpose of protecting the output terminal from both overvoltage and short circuit.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (3)

1. A protection circuit for a switching power supply device having multiple outputs, comprising:
a voltage abnormality detection unit for receiving a first output voltage and a second output voltage of the switching power supply device, determining whether the first output voltage is greater than a first default value, and determining whether the second output voltage is greater than a second default value, and generating a coupling signal if any of the determination results is yes; and
a protection trigger signal generating unit for generating and latching a protection trigger signal according to the coupling signal, and providing the protection trigger signal to a first pulse width modulation control circuit and a second pulse width modulation control circuit of the switching power supply device, so as to control the first pulse width modulation control circuit and the second pulse width modulation control circuit to stop outputting a first pulse width modulation signal and a second pulse width modulation signal respectively;
a signal receiving unit having a first end and a second end, the first end being used for receiving an operating voltage, and when the signal receiving unit receives the coupling signal, the first end and the second end are turned on;
an impedance having one end coupled to the second end and the other end coupled to a reference potential;
a PNP type bipolar junction transistor having a first emitter, a first base and a first collector, the first emitter for receiving the operating voltage;
an NPN-type bipolar junction transistor having a second emitter, a second base and a second collector, the second base being coupled to the second terminal and the first collector, the second collector being coupled to the first base, and the second emitter being coupled to the reference potential; and
a diode, the cathode of which is coupled to the second collector and the anode of which is coupled to the first pwm control circuit and the second pwm control circuit, for outputting the protection trigger signal.
2. The protection circuit of claim 1, wherein the voltage abnormality detection unit comprises:
a first diode, the anode of which is used for receiving the first output voltage;
a second diode, the anode of which is used for receiving the second output voltage;
a signal transmission unit having a first terminal and a second terminal, wherein the first terminal is coupled to the cathode of the first diode and the cathode of the second diode, and the signal transmission unit generates the coupling signal when the first terminal and the second terminal are turned on;
a voltage-controlled switch having a third terminal, a fourth terminal and a reference terminal, wherein the third terminal is coupled to the second terminal, the fourth terminal is coupled to a reference potential, and when the voltage of the reference terminal reaches a third default value, the voltage-controlled switch makes the third terminal and the fourth terminal form a conduction state;
a first Zener diode, the cathode of which is coupled with the cathode of the first diode;
a first impedance, one end of which is coupled with the anode of the first Zener diode;
a second impedance, one end of which is coupled to the other end of the first impedance, and the other end of which is coupled to the reference potential; and
a third impedance, one end of which is coupled to the anode of the second diode and the other end of which is coupled to the reference potential.
3. The protection circuit of claim 2, wherein the voltage abnormality detection unit further receives a third output voltage of the switching power supply device, and further determines whether the third output voltage is greater than a fourth default value, and generates the coupling signal when the third output voltage is greater than the fourth default value, the voltage abnormality detection unit further comprising:
a third diode, the anode of which is used for receiving the third output voltage;
a second Zener diode, the cathode of which is coupled with the cathode of the third diode; and
a fourth impedance, one end of which is coupled to the anode of the second zener diode and the other end of which is coupled to the other end of the first impedance.
CN201611270665.XA 2016-12-29 2016-12-29 Protection circuit suitable for switching type power supply device with multiple outputs Active CN108258655B (en)

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CN102025275A (en) * 2011-01-11 2011-04-20 鞍山亚世光电显示有限公司 Intelligent digital regulating power supply for liquid crystal display (LCD) module detection system
CN102820645A (en) * 2012-06-08 2012-12-12 深圳市共进电子股份有限公司 High-precision overvoltage protection circuit and switch power circuit with multiplexed output
CN104953828A (en) * 2014-03-31 2015-09-30 英飞凌科技奥地利有限公司 Digital voltage regulator controller with multiple configurations

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101657054B (en) * 2009-02-18 2016-01-20 上海威廉照明电气有限公司 A kind of modified node method with the power supply circuits of power factor correction

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102025275A (en) * 2011-01-11 2011-04-20 鞍山亚世光电显示有限公司 Intelligent digital regulating power supply for liquid crystal display (LCD) module detection system
CN102820645A (en) * 2012-06-08 2012-12-12 深圳市共进电子股份有限公司 High-precision overvoltage protection circuit and switch power circuit with multiplexed output
CN104953828A (en) * 2014-03-31 2015-09-30 英飞凌科技奥地利有限公司 Digital voltage regulator controller with multiple configurations

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