Power supply device for suppressing transient voltage

Abstract

The present invention discloses a power supply device for suppressing transient voltage, which is applied to an input voltage. The power supply device for suppressing transient voltage comprises a power supply circuit, a feedback signal generating circuit and a feedback signal control circuit. If the power supply circuit stops receiving the input voltage, the feedback signal control circuit controls the feedback signal generating circuit to discharge so that the feedback signal generating circuit controls the power supply circuit to reduce an output voltage, so that when the power supply circuit receives the input voltage again, the power supply circuit avoids generating an output overvoltage condition for the output voltage.

Description

Technical Field

[0001] The invention relates to a power supply device, in particular to a power supply device capable of suppressing transient voltage. Background Art

[0002] A power supply circuit of the related art receives an input voltage to convert the input voltage into an output voltage; the power supply circuit of the related art can utilize a feedback signal generating circuit of the related art to feedback control the output voltage; generally, the feedback signal generating circuit of the related art can include an operational amplifier of the related art and a reference voltage source of the related art, the operational amplifier of the related art is electrically connected to the reference voltage source of the related art, the operational amplifier of the related art compares a divided voltage of the output voltage and a reference voltage of the reference voltage source of the related art to feedback control the output voltage; thereby, the power supply circuit of the related art can generate a stable output voltage.

[0003] If the power supply circuit of the related technology stops receiving the input voltage, the feedback signal generating circuit of the related technology will detect that the output voltage has decreased, so the feedback signal generating circuit of the related technology will control the power supply circuit of the related technology to require the power supply circuit of the related technology to increase the output voltage; if the operational amplifier of the related technology still works during the period when the power supply circuit of the related technology stops receiving the input voltage to require the power supply circuit of the related technology to increase the output voltage, then when the power supply circuit of the related technology receives the input voltage again, the output voltage will produce an output overvoltage condition, especially when the power supply circuit of the related technology is in a light load state or a no-load state. Summary of the invention

[0004] To solve the above problems, an object of the present invention is to provide a power supply device capable of suppressing transient voltage.

[0005] To achieve the above-mentioned purpose of the present invention, the power supply device for suppressing transient voltage of the present invention is applied to an input voltage, and the power supply device for suppressing transient voltage comprises: a power supply circuit; a feedback signal generating circuit, the feedback signal generating circuit is electrically connected to the power supply circuit; and a feedback signal control circuit, the feedback signal control circuit is electrically connected to the power supply circuit and the feedback signal generating circuit, wherein if the power supply circuit stops receiving the input voltage, the feedback signal control circuit controls the feedback signal generating circuit to discharge so that the feedback signal generating circuit controls the power supply circuit to reduce an output voltage, so that when the power supply circuit receives the input voltage again, the power supply circuit avoids generating an output overvoltage condition for the output voltage.

[0006] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the power supply circuit includes: an auxiliary voltage generating subcircuit, and the auxiliary voltage generating subcircuit is electrically connected to the feedback signal control circuit.

[0007] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the feedback signal control circuit includes: a voltage detection subcircuit, and the voltage detection subcircuit is electrically connected to the auxiliary voltage generation subcircuit.

[0008] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the feedback signal control circuit further includes: a voltage adjustment subcircuit, which is electrically connected to the power supply circuit, the feedback signal generating circuit and the voltage detection subcircuit, wherein if the power supply circuit stops receiving the input voltage, the voltage detection subcircuit detects that the auxiliary voltage generating subcircuit stops generating an auxiliary voltage and the voltage detection subcircuit notifies the voltage adjustment subcircuit that the auxiliary voltage generating subcircuit stops generating the auxiliary voltage, so that the voltage adjustment subcircuit controls the feedback signal generating circuit to discharge.

[0009] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the feedback signal generating circuit includes: a reference voltage source, which is electrically connected to the voltage adjustment sub-circuit, wherein when the voltage adjustment sub-circuit controls the feedback signal generating circuit to discharge, the voltage adjustment sub-circuit outputs a low voltage to the reference voltage source, so that the reference voltage source stops working.

[0010] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the voltage detection subcircuit includes: a first Zener diode, which is electrically connected to the auxiliary voltage generating subcircuit and the voltage adjustment subcircuit; and a first resistor, which is electrically connected to the first Zener diode and the voltage adjustment subcircuit.

[0011] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the voltage adjustment subcircuit includes: a first diode, the first diode is electrically connected to the first Zener diode and the first resistor; a second diode, the second diode is electrically connected to the first diode and the reference voltage source; and a second resistor, the second resistor is electrically connected to the feedback signal generating circuit, the first diode and the second diode.

[0012] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the feedback signal generating circuit further includes: an operational amplifier, the operational amplifier is electrically connected to the reference voltage source and the second resistor; and a feedback sub-circuit, the feedback sub-circuit is electrically connected to the operational amplifier and the power supply circuit, wherein the operational amplifier includes an operational amplifier output terminal, an operational amplifier inverting input terminal and an operational amplifier non-inverting input terminal; the operational amplifier output terminal is electrically connected to the feedback sub-circuit; the operational amplifier non-inverting input terminal is electrically connected to the reference voltage source.

[0013] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the feedback signal generating circuit further includes: a first voltage-dividing resistor, the first voltage-dividing resistor is electrically connected to the power supply circuit, the second resistor, the inverting input terminal of the operational amplifier and the feedback sub-circuit; and a second voltage-dividing resistor, the second voltage-dividing resistor is electrically connected to the first voltage-dividing resistor and the inverting input terminal of the operational amplifier, wherein when the reference voltage source stops working, a first voltage at the non-inverting input terminal of the operational amplifier is less than a first voltage-dividing resistor between the first voltage-dividing resistor and the second voltage-dividing resistor, so that the operational amplifier controls the power supply circuit through the operational amplifier output terminal and the feedback sub-circuit to reduce the output voltage.

[0014] Furthermore, in a specific embodiment of the power supply device for suppressing transient voltage of the present invention as described above, the power supply circuit further includes: a pulse width modulation control subcircuit, the pulse width modulation control subcircuit is electrically connected to the feedback subcircuit; a power switch, the power switch is electrically connected to the pulse width modulation control subcircuit; a transformer, the transformer is electrically connected to the power switch and the auxiliary voltage generating subcircuit; a rectifier filter circuit, the rectifier filter circuit is electrically connected to the transformer, the feedback subcircuit, the first voltage-dividing resistor and the second resistor; and an output-end capacitor, the output-end capacitor is electrically connected to the first voltage-dividing resistor, the second resistor, the rectifier filter circuit and the feedback subcircuit.

[0015] The effect of the present invention is that if the feedback signal generating circuit is still working during the period when the power supply circuit stops receiving the input voltage, then when the power supply circuit receives the input voltage again, the power supply circuit can avoid the output overvoltage condition. Furthermore, in a specific embodiment of the present invention, the effect of the present invention is that if the operational amplifier is still working during the period when the power supply circuit stops receiving the input voltage, then when the power supply circuit receives the input voltage again, the power supply circuit can avoid the output overvoltage condition, especially when the power supply circuit is in a light load state or a no-load state; wherein, if the operational amplifier is still working during the period when the power supply circuit stops receiving the input voltage, the operational amplifier is forced to control the pulse width modulation control subcircuit through the operational amplifier output terminal and the feedback subcircuit to reduce the output voltage.

[0016] In order to further understand the techniques, means and effects adopted by the present invention to achieve the predetermined objectives, please refer to the following detailed description and drawings of the present invention. It is believed that the objectives, features and characteristics of the present invention can be deeply and specifically understood thereby. However, the drawings are only provided for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A block diagram of a first specific embodiment of a power supply device for suppressing transient voltage according to the present invention;

[0018] Figure 2 FIG. 4 is a circuit block diagram of a second specific embodiment of a power supply device for suppressing transient voltage according to the present invention.

[0019] Explanation of symbols in the accompanying drawings:

[0020] 10: A power supply device for suppressing transient voltage;

[0021] 20: power supply circuit;

[0022] 30: feedback signal generating circuit;

[0023] 40: feedback signal control circuit;

[0024] 50: input voltage;

[0025] 60: output voltage;

[0026] 202: pulse width modulation control subcircuit;

[0027] 204: power switch;

[0028] 206: transformer;

[0029] 208: rectifier filter circuit;

[0030] 210: auxiliary voltage generating sub-circuit;

[0031] 212: output terminal capacitance;

[0032] 214: auxiliary voltage;

[0033] 302: reference voltage source;

[0034] 306: operational amplifier;

[0035] 308: Operational amplifier output terminal;

[0036] 310: operational amplifier inverting input terminal;

[0037] 312: non-inverting input terminal of operational amplifier;

[0038] 314: a first voltage-dividing resistor;

[0039] 316: second voltage-dividing resistor;

[0040] 318: feedback sub-circuit;

[0041] 320: first voltage;

[0042] 322: first partial pressure;

[0043] 328: reference voltage;

[0044] 402: voltage detection sub-circuit;

[0045] 404: voltage adjustment sub-circuit;

[0046] 406: low voltage;

[0047] 410: a first Zener diode;

[0048] 412: a first resistor;

[0049] 414: a first diode;

[0050] 416: a second diode;

[0051] 420: a second resistor;

[0052] 424: High voltage. DETAILED DESCRIPTION

[0053] In the technical solutions disclosed in this disclosure, many specific details are provided to provide a thorough understanding of the specific embodiments of the present invention; however, those skilled in the art should know that the present invention can still be practiced without one or more of these specific details; in other cases, well-known details are not shown or described to avoid obscuring the main technical features of the present invention. The technical content and detailed description of the present invention are described as follows with the accompanying drawings:

[0054] Please refer to Figure 1 , which is a block diagram of a first specific embodiment of a power supply device for suppressing transient voltage of the present invention. A power supply device 10 for suppressing transient voltage of the present invention is applied to an input voltage 50; the power supply device 10 for suppressing transient voltage comprises a power supply circuit 20, a feedback signal generating circuit 30 and a feedback signal control circuit 40; the above components are electrically connected to each other. If the power supply circuit 20 stops receiving the input voltage 50, the feedback signal control circuit 40 controls the feedback signal generating circuit 30 to discharge so that the feedback signal generating circuit 30 controls the power supply circuit 20 to reduce an output voltage 60, so that when the power supply circuit 20 receives the input voltage 50 again, the power supply circuit 20 avoids generating an output overvoltage condition for the output voltage 60.

[0055] Furthermore, the input voltage 50 may be a DC voltage or an AC voltage. The power supply circuit 20 is used to convert the input voltage 50 into the output voltage 60; the power supply circuit 20 may be a power supply, but the present invention is not limited thereto. The feedback signal generating circuit 30 is used to detect the output voltage 60 to control the power supply circuit 20 to feedback control the output voltage 60; the feedback signal generating circuit 30 may be a feedback signal generator, but the present invention is not limited thereto. The feedback signal control circuit 40 may be a feedback signal controller, but the present invention is not limited thereto. The above-mentioned power supply circuit 20 stops receiving the input voltage 50 to cut off the power supply of the input voltage 50, but the present invention is not limited thereto.

[0056] Furthermore, the feedback signal control circuit 40 is used to detect an auxiliary voltage 214 provided by the power supply circuit 20; if the auxiliary voltage 214 exists (that is, the power supply circuit 20 receives the input voltage 50; the input voltage 50 is not powered off; the feedback signal control circuit 40 receives the auxiliary voltage 214), the feedback signal control circuit 40 generates and transmits a high voltage 424 to the feedback signal generating circuit 30 so that the feedback signal generating circuit 30 works normally (that is, the feedback signal generating circuit 30 detects that the auxiliary voltage 214 exists). The output voltage 60 is measured to control the power supply circuit 20 to feedback control the output voltage 60); if the auxiliary voltage 214 does not exist (that is, the power supply circuit 20 stops receiving the input voltage 50; the input voltage 50 is powered off; the feedback signal control circuit 40 stops receiving the auxiliary voltage 214), the feedback signal control circuit 40 generates and transmits a low voltage 406 to the feedback signal generating circuit 30, so that the feedback signal generating circuit 30 can discharge to avoid requiring the power supply circuit 20 to increase the output voltage 60.

[0057] Please refer to Figure 2 , which is a circuit block diagram of a second specific embodiment of a power supply device for suppressing transient voltage of the present invention; Figure 2 The components shown are Figure 1 The components shown are the same and their description will not be repeated here for the sake of brevity. The power supply circuit 20 includes a pulse width modulation control subcircuit 202, a power switch 204, a transformer 206, a rectifier filter circuit 208, an auxiliary voltage generation subcircuit 210 and an output capacitor 212; the feedback signal generation circuit 30 includes a reference voltage source 302, the operational amplifier 306, a first voltage-dividing resistor 314, a second voltage-dividing resistor 316 and a feedback subcircuit 318; the feedback signal control circuit 40 includes a voltage detection subcircuit 402 and a voltage adjustment subcircuit 404; the operational amplifier 306 includes an operational amplifier output terminal 308, an operational amplifier inverting input terminal 310 and an operational amplifier non-inverting input terminal 312; the voltage detection subcircuit 402 includes a first Zener diode 410 and a first resistor 412; the voltage adjustment subcircuit 404 includes a first diode 414, a second diode 416 and a second resistor 420; the above components are electrically connected to each other.

[0058] If the power supply circuit 20 stops receiving the input voltage 50, the voltage detection sub-circuit 402 detects that the auxiliary voltage generating sub-circuit 210 stops generating the auxiliary voltage 214 and the voltage detection sub-circuit 402 notifies the voltage adjustment sub-circuit 404 that the auxiliary voltage generating sub-circuit 210 stops generating the auxiliary voltage 214, so that the voltage adjustment sub-circuit 404 outputs the low voltage 406 to the reference voltage source 302, so that the reference voltage source 302 stops working and a first voltage 320 at the non-inverting input terminal 312 of the operational amplifier is less than a first divided voltage 322 between the first voltage divider resistor 314 and the second voltage divider resistor 316, so that the operational amplifier 306 controls the power supply circuit 20 through the operational amplifier output terminal 308 and the feedback sub-circuit 318 to reduce the output voltage 60.

[0059] If the power supply circuit 20 stops receiving the input voltage 50, then:

[0060] An anode voltage of the first diode 414 = [the output voltage 60×a first resistance value of the first resistor 412 / (the first resistance value of the first resistor 412 + a second resistance value of the second resistor 420 )] + a first barrier voltage of the first diode 414

[0061] The low voltage 406 = the anode voltage of the first diode 414 - a second barrier voltage of the second diode 416 = [the output voltage 60 × the first resistance value of the first resistor 412 / (the first resistance value of the first resistor 412 + the second resistance value of the second resistor 420) ] + the first barrier voltage of the first diode 414 - the second barrier voltage of the second diode 416

[0062] If the first barrier voltage of the first diode 414 is equal to the second barrier voltage of the second diode 416 (eg, 0.7 volts), then:

[0063] The low voltage 406 = the output voltage 60×the first resistance value of the first resistor 412 / (the first resistance value of the first resistor 412 + the second resistance value of the second resistor 420 )

[0064] The reference voltage source 302 may be a Zener diode, a step-down integrated circuit, a certain current source circuit, or a voltage divider circuit similar to the voltage divider circuit including the first voltage divider resistor 314 and the second voltage divider resistor 316, but the present invention is not limited thereto; the first resistor 412 and the second resistor 420 may be appropriately designed (for example, the first resistance value of the first resistor 412 is relatively small), so that the low voltage 406 is small enough that the reference voltage source 302 stops providing a reference voltage 328 to the non-inverting input terminal 312 of the operational amplifier (that is, the reference voltage source 302 stops working). If the power supply circuit 20 stops receiving the input voltage 50, the output voltage 60 is provided by the output terminal capacitor 212 and gradually decreases.

[0065] Furthermore, if the power supply circuit 20 receives the input voltage 50, the voltage detection subcircuit 402 detects that the auxiliary voltage generating subcircuit 210 generates the auxiliary voltage 214 and the voltage detection subcircuit 402 notifies the voltage adjustment subcircuit 404 that the auxiliary voltage generating subcircuit 210 generates the auxiliary voltage 214, so that the voltage adjustment subcircuit 404 outputs the high voltage 424 to the reference voltage source 302, so that the reference voltage source 302 provides the reference voltage 328 to the non-inverting input terminal 312 of the operational amplifier, so that the operational amplifier 306 can operate normally.

[0066] If the power supply circuit 20 receives the input voltage 50, then:

[0067] A first voltage across the first resistor 412 = the auxiliary voltage 214 − a second voltage across the first Zener diode 410

[0068] The anode voltage of the first diode 414 = the first voltage across the first resistor 412 + the first barrier voltage of the first diode 414 = the auxiliary voltage 214 - the second voltage across the first Zener diode 410 + the first barrier voltage of the first diode 414

[0069] The high voltage 424 = the anode voltage of the first diode 414 − the second barrier voltage of the second diode 416 = the auxiliary voltage 214 − the second voltage across the first Zener diode 410 + the first barrier voltage of the first diode 414 − the second barrier voltage of the second diode 416

[0070] If the first barrier voltage of the first diode 414 is equal to the second barrier voltage of the second diode 416 (eg, 0.7 volts), then:

[0071] The high voltage 424 = the auxiliary voltage 214 - the second voltage across the first Zener diode 410

[0072] For example, if the auxiliary voltage 214 is 10 volts, and if the second voltage across the first Zener diode 410 (i.e., the breakdown voltage) is 7.5 volts, the high voltage 424 is 2.5 volts; if the reference voltage source 302 is a Zener diode having a breakdown voltage of 1.25 volts, the high voltage 424 (2.5 volts) transmitted to the reference voltage source 302 will cause the reference voltage source 302 to provide the reference voltage 328 (1.25 volts) to the non-inverting input terminal 312 of the operational amplifier, so that the operational amplifier 306 can operate normally.

[0073] Furthermore, the operational amplifier 306 can work normally as described above. If the first voltage 320 at the non-inverting input terminal 312 of the operational amplifier is less than the first divided voltage 322 between the first voltage-dividing resistor 314 and the second voltage-dividing resistor 316, the operational amplifier 306 controls the PWM control subcircuit 202 through the operational amplifier output terminal 308 and the feedback subcircuit 318 to reduce a conduction rate of the power switch 204 to reduce the output voltage 60. If the first voltage 320 at the non-inverting input terminal 312 of the operational amplifier is greater than the first divided voltage 322 between the first voltage-dividing resistor 314 and the second voltage-dividing resistor 316, the operational amplifier 306 controls the PWM control subcircuit 202 through the operational amplifier output terminal 308 and the feedback subcircuit 318 to increase the conduction rate of the power switch 204 to increase the output voltage 60.

[0074] Furthermore, one end of the first Zener diode 410 is connected to the auxiliary voltage generating sub-circuit 210, and the other end of the first Zener diode 410 is connected to the voltage adjusting sub-circuit 404; one end of the first resistor 412 is connected to the voltage adjusting sub-circuit 404 and the other end of the first Zener diode 410, and the other end of the first resistor 412 is connected to the ground; one end of the first diode 414 is connected to the other end of the first Zener diode 410 and one end of the first resistor 412; one end of the second diode 416 is connected to the other end of the first diode 414, and the other end of the second diode 416 is connected to the reference voltage source 302; one end of the second resistor 420 is connected to the feedback signal generating circuit 30, and the other end of the second resistor 420 is connected to the other end of the first diode 414 and one end of the second diode 416.

[0075] The effect of the present invention is that if the feedback signal generating circuit 30 is still working during the period when the power supply circuit 20 stops receiving the input voltage 50, the power supply circuit 20 can avoid the output overvoltage condition when the power supply circuit 20 receives the input voltage 50 again. Furthermore, in a specific embodiment of the present invention, if the operational amplifier 306 is still working during the period when the power supply circuit 20 stops receiving the input voltage 50, the power supply circuit 20 can avoid the output overvoltage condition when the power supply circuit 20 receives the input voltage 50 again, especially when the power supply circuit 20 is in a light load state or a no load state; wherein, if the operational amplifier 306 is still working during the period when the power supply circuit 20 stops receiving the input voltage 50, the operational amplifier 306 is forced to control the pulse width modulation control subcircuit 202 through the operational amplifier output terminal 308 and the feedback subcircuit 318 to reduce the output voltage 60.

[0076] The above description is only a preferred embodiment of the present invention, and it cannot limit the scope of the implementation of the present invention. That is, all equivalent changes and modifications made according to the claims of the present invention should still fall within the scope of the patent coverage of the present invention. The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A power supply device for suppressing transient voltage, applied to an input voltage, characterized in that: The power supply device for suppressing transient voltage comprises: a power supply circuit; a feedback signal generating circuit, the feedback signal generating circuit being electrically connected to the power supply circuit; and a feedback signal control circuit, the feedback signal control circuit is electrically connected to the power supply circuit and the feedback signal generating circuit, If the power supply circuit stops receiving the input voltage, the feedback signal control circuit controls the feedback signal generating circuit to discharge so that the feedback signal generating circuit controls the power supply circuit to reduce an output voltage, so that when the power supply circuit receives the input voltage again, the power supply circuit avoids generating an output overvoltage condition for the output voltage; The power supply circuit includes: an auxiliary voltage generating sub-circuit, the auxiliary voltage generating sub-circuit being electrically connected to the feedback signal control circuit; The feedback signal control circuit includes: a voltage detection sub-circuit, the voltage detection sub-circuit being electrically connected to the auxiliary voltage generation sub-circuit; and a voltage adjustment sub-circuit, the voltage adjustment sub-circuit being electrically connected to the power supply circuit, the feedback signal generating circuit and the voltage detection sub-circuit; The voltage detection subcircuit includes: a first Zener diode electrically connected to the auxiliary voltage generating sub-circuit and the voltage regulating sub-circuit; and a first resistor electrically connected to the first Zener diode and the voltage adjustment sub-circuit; The voltage adjustment subcircuit comprises: a first diode electrically connected to the first Zener diode and the first resistor; a second diode electrically connected to the first diode and a reference voltage source; and a second resistor electrically connected to the feedback signal generating circuit, the first diode and the second diode; If the power supply circuit stops receiving the input voltage, the voltage detection subcircuit detects that the auxiliary voltage generating subcircuit stops generating an auxiliary voltage and the voltage detection subcircuit notifies the voltage adjustment subcircuit that the auxiliary voltage generating subcircuit stops generating the auxiliary voltage, so that the voltage adjustment subcircuit controls the feedback signal generating circuit to discharge.

2. The power supply device for suppressing transient voltage according to claim 1, characterized in that: The feedback signal generating circuit comprises: a reference voltage source, the reference voltage source being electrically connected to the voltage adjustment sub-circuit, When the voltage adjustment sub-circuit controls the feedback signal generating circuit to discharge, the voltage adjustment sub-circuit outputs a low voltage to the reference voltage source, so that the reference voltage source stops working.

3. The power supply device for suppressing transient voltage as claimed in claim 1, characterized in that: The feedback signal generating circuit further comprises: an operational amplifier electrically connected to the reference voltage source and the second resistor; and a feedback sub-circuit, the feedback sub-circuit is electrically connected to the operational amplifier, the power supply circuit and the second resistor, The operational amplifier includes an operational amplifier output terminal, an operational amplifier inverting input terminal and an operational amplifier non-inverting input terminal; the operational amplifier output terminal is electrically connected to the feedback sub-circuit; and the operational amplifier non-inverting input terminal is electrically connected to the reference voltage source.

4. The power supply device for suppressing transient voltage as claimed in claim 3, characterized in that: The feedback signal generating circuit further comprises: a first voltage-dividing resistor electrically connected to the power supply circuit, the second resistor, the inverting input terminal of the operational amplifier and the feedback sub-circuit; and a second voltage-dividing resistor, the second voltage-dividing resistor being electrically connected to the first voltage-dividing resistor and the inverting input terminal of the operational amplifier, When the reference voltage source stops working, a first voltage at the non-inverting input terminal of the operational amplifier is less than a first divided voltage between the first voltage-dividing resistor and the second voltage-dividing resistor, so that the operational amplifier controls the power supply circuit through the operational amplifier output terminal and the feedback sub-circuit to reduce the output voltage.

5. The power supply device for suppressing transient voltage as claimed in claim 4, characterized in that: The power supply circuit further comprises: a pulse width modulation control subcircuit, the pulse width modulation control subcircuit being electrically connected to the feedback subcircuit; a power switch electrically connected to the pulse width modulation control subcircuit; a transformer electrically connected to the power switch and the auxiliary voltage generating sub-circuit; a rectifying and filtering circuit, the rectifying and filtering circuit being electrically connected to the transformer, the feedback sub-circuit, the first voltage-dividing resistor and the second resistor; and An output capacitor is electrically connected to the first voltage-dividing resistor, the second resistor, the rectifying and filtering loop, and the feedback sub-circuit.

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