Power supply circuit

Abstract

The utility model discloses a power supply circuit. The power supply circuit comprises a first filtering unit, a rectification unit, a conversion unit, a sampling unit, a second filtering unit and a first common mode inductor. The rectification unit is used for generating direct-current voltage, the conversion unit carries out voltage conversion on the direct-current voltage to form conversion voltage, and the second filtering unit filters the conversion voltage to generate second filtering voltage. The sampling unit samples the voltage difference between the conversion voltage and the second filtering voltage to generate a sampling voltage, and the conversion unit also adjusts the conversion voltage based on the sampling voltage. The first end of the first common-mode inductor is connected with the second filtering unit to receive the second filtering voltage, and the fourth end of the first common-mode inductor is used for generating the output voltage. According to the power supply circuit, alternating-current and direct-current input voltage is rectified into direct-current voltage in a unified mode through the rectifying unit, then the direct-current voltage is converted into needed voltage through the conversion unit, and the effect that alternating-current and direct-current input is universal is achieved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to general power supply technical field, specifically about a power supply circuit. BACKGROUND

[0002] At present, the design of power supply part of industrial electronic products mainly has three schemes:

[0003] 1. First, use transformer to reduce voltage, then rectify in secondary, and stabilize voltage. This way can only be applied to AC, and the circuit is relatively bulky.

[0004] 2. Adopt switching power supply. This way is widely applied, but switching power supply usually cannot meet the demand of wide range of input voltage at the same time. Generally, at least two voltage input range circuits are needed.

[0005] 3. Use DCDC way to directly reduce voltage, but it is not suitable for AC power supply.

[0006] It can be seen that at present, there is lack of a power supply which is suitable for AC and DC power supply at the same time and also has wide input range.

[0007] The information disclosed in this background section is only intended to increase an understanding of the general context of the application, and it should not be taken as an acknowledgement or a hint as to the existence of any prior art incited by the information. CONTENT OF THE UTILITY MODEL

[0008] The utility model aims at providing a power supply circuit, which can realize AC and DC input universal under the requirement of wide range of input voltage.

[0009] In order to realize the above-mentioned purpose, the technical scheme provided by a specific embodiment of the utility model is as follows:

[0010] A power supply circuit comprises a first filter unit, a rectifier unit, a conversion unit, a sampling unit, a second filter unit and a first common mode inductor; the first filter unit is connected with an input voltage to filter the input voltage to generate a first filtered voltage; a first input end of the rectifier unit and a second input end of the rectifier unit are connected with the first filter unit to receive the first filtered voltage, a first output end of the rectifier unit is connected with a first reference voltage, and a second output end of the rectifier unit is used to generate a direct current voltage; the conversion unit is connected with the second output end of the rectifier unit to convert the direct current voltage to form a converted voltage; the second filter unit is connected with the conversion unit to filter the converted voltage to generate a second filtered voltage; the sampling unit is connected with the conversion unit and the second filter unit to sample a voltage difference between the converted voltage and the second filtered voltage to generate a sampling voltage, and the conversion unit is further used to adjust the converted voltage based on the sampling voltage; a first end of the first common mode inductor is connected with the second filter unit to receive the second filtered voltage, a fourth end of the first common mode inductor is used to generate an output voltage, a second end of the first common mode inductor is connected with the first reference voltage, and a third end of the first common mode inductor is connected with a second reference voltage.

[0011] In one or more embodiments of the utility model, the first filter unit comprises a first capacitor, a second capacitor and a second common mode inductor, a first end of the first capacitor is connected with a positive pole of the input voltage, a second end of the first capacitor and a first end of the second capacitor are connected with a ground voltage, and a second end of the second capacitor is connected with a negative pole of the input voltage; a first end of the second common mode inductor is connected with the first end of the first capacitor, a second end of the second common mode inductor is connected with the second end of the second capacitor, and a third end and a fourth end of the second common mode inductor are connected with the rectifier unit to generate the first filtered voltage.

[0012] In one or more embodiments of the utility model, the second filter unit comprises a first inductor and a third capacitor, a first end of the first inductor is connected with the conversion unit to receive the converted voltage, a second end of the first inductor and a first end of the third capacitor are connected with the first end of the first common mode inductor to generate the second filtered voltage, and a second end of the third capacitor is connected with the first reference voltage.

[0013] In one or more embodiments of the utility model, the second filter unit further comprises a first diode, an anode of the first diode is connected with the first reference voltage, and a cathode of the first diode is connected with the first end of the first inductor.

[0014] In one or more embodiments of the present application, the second filter unit further comprises a fourth capacitor, a first end of the fourth capacitor is connected with the first end of the first common mode inductor, and a second end of the fourth capacitor is connected with the first reference voltage.

[0015] In one or more embodiments of the present application, the sampling unit comprises a first resistor, a second resistor and a second diode, an anode of the second diode is connected with the second filter unit to receive a second filter voltage, a cathode of the second diode is connected with a first end of the first resistor, a second end of the first resistor and a first end of the second resistor are connected with the conversion unit to generate the sampling voltage, and a second end of the second resistor is connected with the conversion unit to receive the conversion voltage.

[0016] In one or more embodiments of the present application, the sampling unit further comprises a fifth capacitor, a first end of the fifth capacitor is connected with the first end of the first resistor, and a second end of the fifth capacitor is connected with the second end of the second resistor.

[0017] In one or more embodiments of the present application, the power supply circuit further comprises a circuit protection unit connected with the input voltage.

[0018] In one or more embodiments of the present application, the circuit protection unit comprises a fuse, a first end of the fuse is connected with a positive electrode of the input voltage, and a second end of the fuse is connected with the first filter unit; and / or

[0019] the circuit protection unit comprises a pressure sensitive resistor, a first end of the pressure sensitive resistor is connected with a positive electrode of the input voltage, and a second end of the pressure sensitive resistor is connected with a negative electrode of the input voltage; and / or

[0020] the circuit protection unit comprises a gas discharge tube, a first end of the gas discharge tube is connected with a positive electrode of the input voltage, a second end of the gas discharge tube is connected with a negative electrode of the input voltage, and a third end of the gas discharge tube is connected with a ground voltage.

[0021] In one or more embodiments of the present application, the power supply circuit further comprises a sixth capacitor, a first end of the sixth capacitor is connected with a first output end of the rectification unit, and a second end of the sixth capacitor is connected with a second output end of the rectification unit; and / or the power supply circuit further comprises a third resistor, a first end of the third resistor is connected with the first end of the first common mode inductor, and a second end of the third resistor is connected with the second end of the first common mode inductor.

[0022] Compared with the prior art, the power circuit of the utility model realizes the effect of wide range of AC / DC input commonality by rectifying unit first unifying AC / DC input voltage into DC voltage, then converting the required voltage by conversion unit, meanwhile, further filtering interference, smoothing waveform by filter unit, improving EMC resistance by first common mode inductor, finally forming stable DC output voltage. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description, obviously, the drawings in the following description are only some embodiments in the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creative labor.

[0024] Figure 1 It is the circuit schematic diagram of the power circuit in an embodiment of the utility model. DETAILED DESCRIPTION

[0025] In order to make the technical personnel in the art better understand the technical scheme in the utility model, the following will combine the drawings in the embodiments of the utility model, and the technical scheme in the embodiments of the utility model will be clearly and completely described, obviously, the described embodiments are only some embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the utility model.

[0026] The "coupling" or "connection" or "connection" in the specification includes both direct connection and indirect connection. Indirect connection is the connection through intermediate medium, such as the connection through electrically conductive medium, which can have parasitic inductance or parasitic capacitance; indirect connection can also include the connection through other active devices or passive devices on the basis of achieving the same or similar functional purpose, such as the connection through switch, follow-up circuit or other circuit or component. In addition, in the specification, for example, the words "first", "second" and the like are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply a certain actual relationship, quantity or order between the technical features.

[0027] In the detailed description of the specification, the drawings forming a part thereof are referred to, wherein the same reference signs always represent the same components, and wherein the exemplary embodiments can be shown by way of example. It should be understood that other embodiments can be utilized without departing from the scope of the present disclosure, and structural or logical changes can be made. Therefore, the following detailed description should not be regarded as limiting.

[0028] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0029] For the purposes of this disclosure, the phrase “A and / or B” means (A), (B), or (A and B). For the purposes of this disclosure, the phrase “A, B and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0030] Various components and devices may be referred to or shown in the singular (e.g., “MOS transistor”, “transistor”, “switch”, etc.) in this document, but only for the convenience of discussion, and any element referred to in the singular may include multiple such elements as taught herein.

[0031] The description uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," each of which may refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used with respect to embodiments of this disclosure are synonymous.

[0032] like Figure 1 As shown, the power supply circuit in one embodiment of this utility model includes a circuit protection unit 10, a first filter unit 20, a rectification unit, a conversion unit, a sampling unit 30, a second filter unit 40, and a first common-mode inductor L1.

[0033] The circuit protection unit 10 is connected to the input voltage and is used to protect the circuit. The first filtering unit 20 is connected to the input voltage to filter the input voltage and generate a first filtered voltage.

[0034] The first input terminal and the second input terminal of the rectifier unit are connected to the first filter unit 20 to receive the first filtered voltage. The first output terminal of the rectifier unit is connected to the first reference voltage, and the second output terminal of the rectifier unit is used to generate DC voltage.

[0035] The conversion unit is connected to the second output terminal of the rectifier unit to convert the DC voltage into a converted voltage.

[0036] The second filtering unit 40 is connected to the conversion unit to filter the converted voltage and generate a second filtered voltage.

[0037] The sampling unit 30 is connected with the converting unit and the second filtering unit 40 to sample the voltage difference between the converted voltage and the second filtered voltage to generate a sampling voltage, and the converting unit is also used to adjust the converted voltage based on the sampling voltage.

[0038] The first end of the first common-mode inductor L1 is connected with the second filtering unit 40 to receive the second filtered voltage, the fourth end of the first common-mode inductor L1 is used to generate an output voltage, the second end of the first common-mode inductor L1 is connected with a first reference voltage, and the third end of the first common-mode inductor L1 is connected with a second reference voltage.

[0039] The second reference voltage is a ground voltage of an external load circuit, and the first reference voltage is a voltage reference provided inside the power supply circuit without being directly connected with the second reference voltage, so as to avoid external interference affecting the internal power supply circuit and ensure the stability of the output voltage. The first common-mode inductor L1 can improve the anti-EMC capability of the overall circuit.

[0040] As shown in Figure 1 The circuit protection unit 10 includes a fuse F1, a pressure-sensitive resistor RV1 and a gas discharge tube GD1. The first end of the fuse F1 is connected with the positive pole of the input voltage, and the second end of the fuse F1 is connected with the first filtering unit 20. If overcurrent or short circuit occurs in the input voltage, the fuse F1 can play a protection role.

[0041] In an embodiment, the first end of the pressure-sensitive resistor RV1 and the first end of the gas discharge tube GD1 are connected with the second end of the fuse F1, that is, connected with the positive pole of the input voltage through the fuse F1. In other embodiments, the first end of the pressure-sensitive resistor RV1 and the first end of the gas discharge tube GD1 can also be directly connected with the positive pole of the input voltage. The second end of the pressure-sensitive resistor RV1 and the second end of the gas discharge tube GD1 are connected with the negative pole of the input voltage, and the third end of the gas discharge tube GD1 is connected with the ground voltage. The pressure-sensitive resistor RV1 and the gas discharge tube GD1 can suppress the surge on the input voltage to avoid damage to the subsequent circuit.

[0042] The input voltage can be alternating current or direct current. The ground voltage can be a chassis ground voltage.

[0043] As shown in Figure 1 The first filtering unit 20 includes a first capacitor C1, a second capacitor C2 and a second common-mode inductor L2. The first end of the first capacitor C1 is connected with the second end of the fuse F1, that is, connected with the positive pole of the input voltage through the fuse F1. In other embodiments, the first end of the first capacitor C1 can also be directly connected with the positive pole of the input voltage. The second end of the first capacitor C1 and the first end of the second capacitor C2 are connected with the ground voltage, and the second end of the second capacitor C2 is connected with the negative pole of the input voltage.

[0044] The first end of the second common-mode inductor L2 is connected with the first end of the first capacitor C1, the second end of the second common-mode inductor L2 is connected with the second end of the second capacitor C2, and the third end of the second common-mode inductor L2 and the fourth end of the second common-mode inductor L2 are connected with the rectifying unit to generate the first filtered voltage.

[0045] After the input voltage passes through the first filtering unit 20, the common-mode and differential-mode interference that is upwelled into the signal is filtered, suppressed and attenuated.

[0046] In an embodiment, the rectifying unit comprises a rectifying chip DB1, and the model of the rectifying chip DB1 is preferably DB106S. The pin 4 of the rectifying chip DB1 is the first input end of the rectifying chip DB1, the pin 2 of the rectifying chip DB1 is the second input end of the rectifying chip DB1, the pin 3 of the rectifying chip DB1 is the first output end of the rectifying chip DB1, and the pin 1 of the rectifying chip DB1 is the second output end of the rectifying chip DB1.

[0047] The pin 4 of the rectifying chip DB1 is connected with the fourth end of the second common-mode inductor L2, the pin 2 of the rectifying chip DB1 is connected with the third end of the second common-mode inductor L2, the pin 1 of the rectifying chip DB1 is used to generate a direct current voltage, and the pin 3 of the rectifying chip DB1 is connected with the first reference voltage.

[0048] In an embodiment, the power supply circuit further comprises a sixth capacitor C6, the first end of the sixth capacitor C6 is connected with the pin 1 of the rectifying chip DB1, and the second end of the sixth capacitor C6 is connected with the pin 3 of the rectifying chip DB1. The sixth capacitor C6 is used for filtering and energy storage, so that the direct current voltage output by the rectifying chip DB1 is more stable, and the sixth capacitor C6 can also provide effective energy for the subsequent circuit when the input voltage is very low.

[0049] Preferably, the capacitance of the sixth capacitor C6 is greater than or equal to 15uF, and further, the capacitance of the sixth capacitor C6 is greater than or equal to 30uF.

[0050] As shown in FIG. 1, the converting unit comprises a converting chip U1, and the model of the converting chip U1 is preferably XD308H, which is a wide-range DCDC converter. Figure 1 In an embodiment, the pin 1 of the converting chip U1 is a power supply end, the pin 2 of the converting chip U1 is an output end, the pin 3 of the converting chip U1 is a feedback end, the pin 4 of the converting chip U1 is a current detection end, and the pins 5-8 of the converting chip U1 are input ends.

[0051] The pins 5-8 of the converting chip U1 are connected with the pin 1 of the rectifying chip DB1 to receive the direct current voltage, and the converting chip U1 can perform step-down conversion on the direct current voltage and output through the pin 2 of the converting chip U1.

[0052] A bootstrap capacitor C7 can also be connected in series between the pin 1 and the pin 2 of the converting chip U1 to ensure that the internal MOS tube of the converting chip U1 can be turned on in time.

[0053] A resistor R4 can be connected in series between pin 4 and pin 2 of the conversion chip U1 to adjust the output current of the conversion chip U1.

[0054] Pin 3 of the conversion chip U1 is connected to the sampling unit 30 to receive the sampled voltage. The conversion chip U1 can compare the sampled voltage with the internal reference to form a closed loop and then output a constant conversion voltage.

[0055] like Figure 1 As shown, the second filter unit 40 includes a first inductor L3 and a third capacitor C3. The first end of the first inductor L3 is connected to pin 2 of the conversion chip U1 to receive the conversion voltage. The second end of the first inductor L3 and the first end of the third capacitor C3 are connected to the first end of the first common-mode inductor L1 to generate a second filter voltage. The second end of the third capacitor C3 is connected to the first reference voltage.

[0056] The first inductor L3 and the third capacitor C3 form an LC filter circuit that can filter the high-frequency pulse voltage output by the MOS transistor inside the conversion chip U1 during high-speed conduction into a low-ripple DC second filter voltage without loss.

[0057] In one embodiment, the second filter unit 40 further includes a fourth capacitor C4. The first terminal of the fourth capacitor C4 is connected to the first terminal of the first common-mode inductor L1, and the second terminal of the fourth capacitor C4 is connected to the first reference voltage. The fourth capacitor C4 can further filter the second filter voltage to reduce its ripple. Three fourth capacitors C4 can be connected in parallel to improve the filtering effect.

[0058] In one embodiment, the second filter unit 40 further includes a first diode D1, the anode of which is connected to a first reference voltage, and the cathode of which is connected to a first terminal of the first inductor L3. The first diode D1 may be a fast recovery diode, used to form a current path for the stored current in the first inductor L3 during the high-speed cutoff period of the MOSFET inside the conversion chip U1, thereby providing freewheeling current during the MOSFET's off period.

[0059] like Figure 1 As shown, the sampling unit 30 includes a first resistor R1, a second resistor R2, and a second diode D2. The anode of the second diode D2 is connected to the second terminal of the first inductor L3 to receive the second filtered voltage. The cathode of the second diode D2 is connected to the first terminal of the first resistor R1. The second terminals of the first resistor R1 and the first terminals of the second resistor R2 are connected to pin 3 of the conversion chip U1 to generate a sampling voltage. The second terminal of the second resistor R2 is connected to pin 2 of the conversion chip U1 to receive the conversion voltage.

[0060] In one embodiment, the sampling unit 30 may further include a fifth capacitor C5, the first terminal of which is connected to the first terminal of the first resistor R1, and the second terminal of which is connected to the second terminal of the second resistor R2. The fifth capacitor C5 is used to filter out interference on the sampling voltage, preventing inaccurate sampling from causing the conversion chip U1 to misadjust and resulting in fluctuations in the conversion voltage.

[0061] like Figure 1 As shown, in one embodiment, the power supply circuit may further include a third resistor R3. The first terminal of the third resistor R3 is connected to the first terminal of the first common-mode inductor L1, and the second terminal of the third resistor R3 is connected to the second terminal of the first common-mode inductor L1. The third resistor R3 can be used as a dummy load resistor to prevent the output voltage from being too high when there is no load.

[0062] In practical operation, the power supply circuit of this application first rectifies the AC and DC input voltages into DC voltage through a rectifier unit, and then converts them into the required voltage through a conversion unit, achieving the effect of universal AC and DC input. By using a wide-range DC-DC converter XD308H as the conversion chip U1, the circuit can have a wider input range and is applicable to a wider range of scenarios.

[0063] By sampling the voltage across the first inductor L3 and sending a portion of it as a sample voltage to pin 3 of the conversion chip U1, the conversion chip U1 receives only one sample voltage. Then, by comparing this sample voltage with the internal reference voltage of the conversion chip U1 and using the resulting voltage difference, the conversion chip U1 can output an adjusted voltage. This voltage is output from pin 2 of the conversion chip U1 and passes through the first inductor L3 again, thus forming a closed-loop control that maintains a constant conversion voltage. This process includes both comparing the conversion chip U1's internal reference voltage with its output conversion voltage and comparing it with an external reference voltage.

[0064] The first filter unit 20 can filter out common-mode and differential-mode interference that enters the input voltage. The second filter unit 40 can further filter out interference and smooth the waveform. Finally, the first common-mode inductor L1 enhances the anti-EMC capability and forms a stable DC output voltage.

[0065] The power supply circuit disclosed herein can be applied to instruments and equipment, including but not limited to tuning fork leveling devices.

[0066] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or the essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, the scope of the present application being defined by the claims appended hereto rather than by the above description, and all the changes which fall within the meaning and the scope of the equivalent elements of the claims are intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0067] Furthermore, it should be understood that although the present specification describes exemplary embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that a person skilled in the art can understand.

Claims

1. A power supply circuit, characterized by comprising: The first filter unit, a rectifier unit, a conversion unit, a sampling unit, a second filter unit and a first common-mode inductor are included. The first filter unit is connected with an input voltage to filter the input voltage to generate a first filtered voltage. A first input end of the rectifier unit and a second input end of the rectifier unit are connected with the first filter unit to receive the first filtered voltage, a first output end of the rectifier unit is connected with a first reference voltage, and a second output end of the rectifier unit is used to generate a direct current voltage. The conversion unit is connected with the second output end of the rectifier unit to convert the direct current voltage to generate a converted voltage. The second filter unit is connected with the conversion unit to filter the converted voltage to generate a second filtered voltage. The sampling unit is connected with the conversion unit and the second filter unit to sample a voltage difference between the converted voltage and the second filtered voltage to generate a sampling voltage, and the conversion unit is further used to adjust the converted voltage based on the sampling voltage. A first end of the first common-mode inductor is connected with the second filter unit to receive the second filtered voltage, a fourth end of the first common-mode inductor is used to generate an output voltage, a second end of the first common-mode inductor is connected with the first reference voltage, and a third end of the first common-mode inductor is connected with a second reference voltage.

2. The power supply circuit of claim 1, wherein The first filter unit includes a first capacitor, a second capacitor and a second common-mode inductor, a first end of the first capacitor is connected with a positive pole of the input voltage, a second end of the first capacitor and a first end of the second capacitor are connected with a ground voltage, and a second end of the second capacitor is connected with a negative pole of the input voltage. A first end of the second common-mode inductor is connected with the first end of the first capacitor, a second end of the second common-mode inductor is connected with the second end of the second capacitor, and a third end and a fourth end of the second common-mode inductor are connected with the rectifier unit to generate the first filtered voltage.

3. The power supply circuit of claim 1, wherein The second filter unit includes a first inductor and a third capacitor, a first end of the first inductor is connected with the conversion unit to receive the converted voltage, a second end of the first inductor and a first end of the third capacitor are connected with the first end of the first common-mode inductor to generate the second filtered voltage, and a second end of the third capacitor is connected with the first reference voltage.

4. The power supply circuit of claim 3, wherein The second filter unit further includes a first diode, an anode of the first diode is connected with the first reference voltage, and a cathode of the first diode is connected with the first end of the first inductor.

5. The power supply circuit of claim 3, wherein The second filter unit further includes a fourth capacitor, a first end of the fourth capacitor is connected with the first end of the first common-mode inductor, and a second end of the fourth capacitor is connected with the first reference voltage.

6. The power supply circuit of claim 1, wherein, The sampling unit comprises a first resistor, a second resistor and a second diode, an anode of the second diode is connected with the second filter unit to receive a second filter voltage, a cathode of the second diode is connected with a first end of the first resistor, a second end of the first resistor and a first end of the second resistor are connected with the conversion unit to generate the sampling voltage, and a second end of the second resistor is connected with the conversion unit to receive the conversion voltage.

7. The power supply circuit of claim 6, wherein, The sampling unit further comprises a fifth capacitor, a first end of the fifth capacitor is connected with the first end of the first resistor, and a second end of the fifth capacitor is connected with the second end of the second resistor.

8. The power supply circuit of claim 1, wherein, The power supply circuit further comprises a circuit protection unit connected with the input voltage.

9. The power supply circuit of claim 8, wherein, The circuit protection unit comprises a fuse, a first end of the fuse is connected with a positive pole of the input voltage, and a second end of the fuse is connected with the first filter unit; and / or The circuit protection unit comprises a voltage-dependent resistor, a first end of the voltage-dependent resistor is connected with a positive pole of the input voltage, and a second end of the voltage-dependent resistor is connected with a negative pole of the input voltage; and / or The circuit protection unit comprises a gas discharge tube, a first end of the gas discharge tube is connected with a positive pole of the input voltage, a second end of the gas discharge tube is connected with a negative pole of the input voltage, and a third end of the gas discharge tube is connected with a ground voltage.

10. The power supply circuit of claim 1, wherein, The power supply circuit further comprises a sixth capacitor, a first end of the sixth capacitor is connected with a first output end of the rectifier unit, and a second end of the sixth capacitor is connected with a second output end of the rectifier unit; and / or The power supply circuit further comprises a third resistor, a first end of the third resistor is connected with a first end of the first common-mode inductor, and a second end of the third resistor is connected with a second end of the first common-mode inductor.

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