Power supply anti-reverse connection circuit and power supply circuit

Abstract

The embodiment of the utility model provides a power supply anti-reverse connection circuit and a power supply circuit, and the circuit comprises a pair of polarity ends which are positive and negative, and a power supply interface which is used for connecting at least one external load through a line to form a power supply loop is formed between the polarity ends; the switch unit is coupled between one polarity end of the pair of polarity ends and the power supply interface, a control end of the switch unit is coupled to the other polarity end, and the switch unit is configured to control on-off of a power supply loop based on the voltage direction between the pair of polarity ends; the positive electrode of the voltage stabilizing diode is coupled with the positive polarity end, and the negative electrode of the voltage stabilizing diode is coupled with the negative polarity end. The on-off of the power supply loop can be automatically controlled according to the voltage direction between the polarity ends through the switch unit, equipment damage or faults caused by wrong connection of the polarity of the power supply are effectively avoided, and the switch unit can reduce the loss under the forward voltage, so that the power consumption is reduced, and the energy utilization efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of power supply circuit, and in particular to a power supply reverse connection prevention circuit and a power supply circuit. BACKGROUND

[0002] In modern electronic devices, power supply reverse connection prevention protection circuit is one of the key components to ensure the safe and reliable operation of the system. Since the battery or external power supply may be incorrectly connected to the device, causing the current to flow in the opposite direction of the design expectation, which not only damages sensitive electronic components, but also can cause serious safety accidents. Therefore, effective power supply reverse connection prevention measures are crucial to protect device performance and user safety. In the related art, the reverse connection prevention methods mainly include using diodes, relays or special integrated circuits (ICs). However, these methods often have certain limitations. For example, using ordinary diodes is simple and direct, but its on-state voltage drop is large, which will cause power loss to increase and serious heating; while using relays requires additional control signals to drive, increasing the complexity and cost of the system; as for special ICs, they usually require specific application scenarios and do not have wide applicability. SUMMARY

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present disclosure is to provide a power supply reverse connection prevention circuit and a power supply circuit to solve the problems in the related art.

[0004] The first aspect of the present disclosure provides a power supply reverse connection prevention circuit, comprising:

[0005] a pair of polarity terminals opposite to each other, forming a power supply interface between them for connecting a line to at least one external load to form a power supply loop;

[0006] a switch unit coupled between one of the pair of polarity terminals and the power supply interface, the control end of the switch unit being coupled to the other polarity terminal, configured to control the on-off of the power supply loop based on the voltage direction between the pair of polarity terminals;

[0007] a voltage stabilizing diode, the anode of the voltage stabilizing diode being coupled to the positive polarity terminal, and the cathode of the voltage stabilizing diode being coupled to the negative polarity terminal.

[0008] In an embodiment of the first aspect, the switch unit comprises a first NMOS tube, the gate of the first NMOS tube being coupled to the positive polarity terminal, the drain of the first NMOS tube being coupled to the negative polarity terminal, and the source of the first NMOS tube being coupled to the power supply interface.

[0009] In an embodiment of the first aspect, the switch unit further comprises a second NMOS transistor connected between the source of the first NMOS transistor and the power supply interface, the gate of the second NMOS transistor is coupled to the positive polarity terminal, the second NMOS transistor shares the source with the first NMOS transistor, and the drain of the second NMOS transistor is coupled to the power supply interface.

[0010] In an embodiment of the first aspect, the switch unit comprises a first PMOS transistor, the gate of the first PMOS transistor is coupled to the negative polarity terminal, the source of the first PMOS transistor is coupled to the positive polarity terminal, and the drain of the first PMOS transistor is coupled to the power supply interface.

[0011] In an embodiment of the first aspect, the switch unit further comprises a second PMOS transistor connected between the source of the first PMOS transistor and the positive polarity terminal, the second PMOS transistor shares the drain with the first PMOS transistor, the gate of the second PMOS transistor is coupled to the negative polarity terminal, and the source of the second PMOS transistor is coupled to the positive polarity terminal.

[0012] In an embodiment of the first aspect, when the switch unit comprises an N-type transistor, the power supply reverse connection prevention circuit further comprises a switch control unit connected between a pair of the polarity terminals and outputting a switch signal corresponding to the voltage direction between a pair of the polarity terminals; the switch signal terminal is coupled to the control terminal of the N-type transistor to control the on-off of the N-type transistor.

[0013] In an embodiment of the first aspect, the switch control unit comprises:

[0014] a resistance voltage dividing unit, both ends of which are coupled to a pair of the polarity terminals, and at least one voltage dividing point of which is coupled to the switch signal terminal.

[0015] In an embodiment of the first aspect, a first capacitor is further provided, which is connected in parallel with the voltage stabilizing diode.

[0016] In an embodiment of the first aspect, a resistance is provided between the power supply interface connected to an external load and the positive polarity terminal.

[0017] The second aspect of the present disclosure provides a power supply circuit, wherein the power supply reverse connection prevention circuit is any one of the above.

[0018] The present disclosure has the following beneficial effects: the switch unit can automatically control the on-off of the power supply circuit according to the voltage direction between the polarity terminals. This effectively avoids the damage or failure of the device caused by the incorrect connection of the power supply polarity, and the switch unit can reduce the loss under the forward voltage, thereby reducing the power consumption and improving the energy utilization efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A module schematic diagram of a power supply reverse connection prevention circuit in an embodiment of the present disclosure is shown.

[0020] Figure 2 A module schematic diagram of a power supply reverse connection prevention circuit in another embodiment of the present disclosure is shown.

[0021] Figure 3 A module schematic diagram of a switch unit provided with a MOS tube in a power supply reverse connection prevention circuit in an embodiment of the present disclosure is shown.

[0022] Figure 4 A module schematic diagram of a switch unit provided with two MOS tubes in a power supply reverse connection prevention circuit in an embodiment of the present disclosure is shown.

[0023] Figure 5 A module schematic diagram of a switch unit provided with a MOS tube in a power supply reverse connection prevention circuit in another embodiment of the present disclosure is shown.

[0024] Figure 6 A module schematic diagram of a switch unit provided with two MOS tubes in a power supply reverse connection prevention circuit in another embodiment of the present disclosure is shown.

[0025] Figure 7 A module schematic diagram of a switch control unit in a power supply reverse connection prevention circuit in an embodiment of the present disclosure is shown.

[0026] Figure 8 A module schematic diagram of a switch control unit including a resistance voltage dividing unit in a power supply reverse connection prevention circuit in an embodiment of the present disclosure is shown.

[0027] Figure 9 A module schematic diagram of a power supply reverse connection prevention circuit including a capacitor in an embodiment of the present disclosure is shown.

[0028] Figure 10 A module schematic diagram of a power supply reverse connection prevention circuit including a capacitor in another embodiment of the present disclosure is shown.

[0029] Figure 11 A module schematic diagram of a power supply reverse connection prevention circuit including a resistance in an embodiment of the present disclosure is shown.

[0030] Figure 12 A module schematic diagram of a power supply reverse connection prevention circuit including a resistance in another embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0031] The advantages and features of the present disclosure will become apparent from specific examples which are given as thorough and complete descriptions of the present disclosure. It will be obvious to those skilled in the art that various other modifications or changes can be made thereto without departing from the spirit and scope of the present disclosure. It is to be understood that the embodiments and features of the present disclosure can be combined with each other, if not incompatible.

[0032] The embodiments of the present disclosure will be described in detail with reference to the drawings, so that those skilled in the art can easily implement the present disclosure. The present disclosure can be embodied in various ways, and is not limited to the embodiments described herein.

[0033] In the present disclosure, the expressions of "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that the specific features, structures, materials, or characteristics expressed in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. Also, the specific features, structures, materials, or characteristics expressed can be combined in any one or a set of embodiments or examples in a suitable manner. In addition, the different embodiments or examples expressed in the present disclosure and the features of the different embodiments or examples can be combined and integrated by those skilled in the art without contradiction.

[0034] In addition, the terms "first", "second", etc. are used only to indicate the purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the present disclosure, the meaning of "a set" is two or more, unless specifically limited.

[0035] In order to clearly explain the present disclosure, devices irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar constituent elements throughout the specification.

[0036] Throughout the specification, when it is said that a device is "connected" to another device, it includes not only the case of "direct connection", but also the case of "indirect connection" in which other elements are interposed therebetween. In addition, when it is said that a device "includes" a certain constituent element, unless specifically stated to the contrary, other constituent elements are not excluded, but it means that other constituent elements can also be included.

[0037] Although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first interface and a second interface, etc. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including" means the presence of stated features, steps, operations, elements, modules, items, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, modules, items, components, and / or groups thereof. As used herein, the term "or" and "and / or" is construed to be inclusive, or means one and any combination of the items. Thus, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition are only possible when the combination of elements, functions, steps or acts are inherently mutually exclusive based on a context.

[0038] The professional terms used herein are only used to refer to specific embodiments and are not intended to limit the disclosure. The singular form used herein, unless the context clearly indicates otherwise, also includes the plural form. The meaning of "comprising" used in the specification is to specify the particular characteristics, regions, integers, steps, operations, elements and / or components, and not to exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0039] Although not differently defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms defined in commonly used dictionaries are to be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0040] In modern electronic devices, power anti-reverse connection protection circuit is one of the key components to ensure the safe and reliable operation of the system. Since the battery or external power supply may be mistakenly connected to the device, causing the current to flow in the opposite direction of the design expectation, which not only damages sensitive electronic components, but also may cause serious safety accidents. In the related art, the anti-reverse connection methods mainly include using diodes, relays or special integrated circuits (ICs). However, these methods often have certain limitations. For example, although the ordinary diode is simple and direct, its on-state voltage drop is large, which will cause the increase of power loss and serious heating; while using a relay requires an additional control signal to drive, increasing the complexity and cost of the system; as for the special IC, it usually requires a specific application scenario, and does not have wide applicability.

[0041] To solve the problems in the related art, an embodiment of the present disclosure provides a power anti-reverse connection circuit, wherein a switching unit is coupled between one of a pair of polarity terminals and a power supply interface, and the control end of the switching unit is coupled to the other polarity terminal. According to the voltage direction between the polarity terminals, the switching unit can determine whether the power supply is correctly connected, and decide whether to close the power supply loop. When a reverse voltage is detected, the switching unit remains in an open state, preventing potential damage caused by misoperation.

[0042] In Figure 1 or Figure 2 In an example, the power anti-reverse connection circuit includes a pair of polarity terminals, a switching unit 300, and a voltage stabilizing diode D1.

[0043] A power supply interface 103 is formed between the pair of polarity terminals for connecting at least one external load 200 to form a power supply loop.

[0044] The switching unit 300 is coupled between one of the pair of polarity terminals and the power supply interface 103, and the control end of the switching unit 300 is coupled to the other polarity terminal, configured to control the on-off of the power supply loop based on the voltage direction between the pair of polarity terminals.

[0045] The voltage stabilizing diode D1 has its anode coupled to the positive polarity terminal 101 and its cathode coupled to the negative polarity terminal 102.

[0046] Specifically, in some embodiments, as shown in Figure 1 or Figure 2 A pair of polarity terminals are input ports of the power anti-reverse connection circuit, used to connect an external power supply. The pair of polarity terminals includes a positive polarity terminal 100 and a negative polarity terminal 200. The external power supply can include a direct current power supply, such as a battery, etc. The power supply interface 103 is an intermediate node between the polarity terminals and the external load 200, which constitutes a connection point allowing current to flow from the power supply to the load. Under normal working conditions, when the power supply is correctly connected, the power supply interface 103 becomes part of the power supply path, allowing current to flow smoothly through the load. When the power supply polarity is reversed, the switching unit 300 at the power supply interface 103 will remain in an open state, preventing current from passing through, thereby protecting the load and circuit from damage. The external load 200 refers to any electrical device or component connected to the power supply interface 103, such as a motor, LED lamp, sensor, etc. These loads rely on stable power supply to perform their intended functions.

[0047] In normal condition, when the power supply is connected to the power interface 103 with the positive terminal 101 connected to one side of the power interface 103 and the load connected to the other side, the current flows from the positive terminal 101 to the power interface 103, then to the load, and finally to the negative terminal 102, which is usually connected to the ground, forming a complete current loop.

[0048] In Figure 1 the example, when the switch unit 300 is arranged between the negative terminal 102 and the power interface 103, and the power supply is connected with the correct polarity, a positive voltage difference is formed between the control end (e.g. gate) of the switch unit 300 and the end connected to the negative terminal 102, so that the switch unit 300 is turned on. The current flows from the positive terminal 101 to the load through the power interface 103, and then returns to the negative terminal 102 through the switch unit 300, forming a complete loop. If the power supply is connected with the reverse polarity, there is not enough positive voltage difference between the control end of the switch unit 300 and the end connected to the negative terminal 102, so the switch unit 300 is not turned on, cutting off the power supply loop and protecting the load and the circuit.

[0049] In Figure 2 the example, when the switch unit 300 is arranged between the positive terminal 101 and the power interface 103, the switch unit 300 is also driven to be turned on according to the voltage difference between the positive terminal 101 and the negative terminal 102, thereby turning on the power supply loop, which will not be described in detail here.

[0050] In some embodiments, in Figure 1 or Figure 2 the example, when the power supply is connected with the correct polarity, the zener diode D1 is in a reverse bias state and is not turned on, so it has no effect on normal operation. In Figure 1 the example, when the power supply is connected with the correct polarity, the zener diode D1 is used to prevent high voltage from breaking the switch unit. The zener diode D1 can provide clamping protection in abnormal conditions such as transient high voltage or surge voltage. When the input voltage exceeds the breakdown voltage of the zener diode D1, it will quickly turn on and clamp the voltage within a safe range, protecting sensitive components from excessive voltage. In Figure 2 the example, when the power supply is connected with the correct polarity, the zener diode D1 can also be used to prevent excessive voltage from affecting the subsequent load 200.

[0051] If the power supply is connected with the reverse polarity (P+ is negative and P- is positive), the switch unit is not turned on, and the zener diode D1 is turned on in the forward direction, forming a low-impedance path that quickly absorbs the reverse voltage, protecting the subsequent circuit from high reverse voltage.

[0052] Optionally, in Figure 3In the example, the switching unit 300 includes a first NMOS transistor Q1, the gate of the first NMOS transistor Q1 is coupled to the positive terminal 101, the drain of the first NMOS transistor Q1 is coupled to the negative terminal 102, and the source of the first NMOS transistor Q1 is coupled to the power supply interface 103.

[0053] Specifically, the above connection method ensures that the gate has a sufficient positive voltage relative to the source to turn on the NMOS transistor in the switching unit 300 only when the power supply is correctly connected. When the power supply is connected with the correct polarity, there is a positive voltage difference between the gate and the source of the NMOS transistor (Vgs > Vth, where Vth is the threshold voltage), causing the NMOS transistor to conduct. Once the NMOS transistor is turned on, current can flow from the positive terminal 101 through the power supply interface 103 to the load, and then back to the negative terminal 102 through the NMOS transistor, forming a complete power supply loop. If the power supply polarity is reversed (positive terminal 101 is negative, negative terminal 102 is positive), the gate of the NMOS transistor does not have enough positive voltage relative to the source (Vgs < Vth), and the NMOS transistor will not conduct. Therefore, even if the user incorrectly reverses the power supply polarity, the power supply loop will not conduct, thus protecting the load and the entire circuit from damage. The NMOS transistor has a low on-resistance R and can conduct with almost no loss under positive voltage, reducing power loss and heat generation. Compared to other types of switching elements, NMOS transistors are readily available and inexpensive, making them suitable for a wide range of applications.

[0054] Optionally, in Figure 4 In this embodiment, the switching unit 300 further includes a second NMOS transistor Q2, which is connected between the source of the first NMOS transistor Q1 and the power supply interface 103. The gate of the second NMOS transistor Q2 is coupled to the positive terminal 101. The second NMOS transistor shares a common source with the first NMOS transistor Q1, and the drain of the second NMOS transistor Q2 is coupled to the power supply interface 103.

[0055] Specifically, in some embodiments, when the two NMOS transistors share a common source, the total on-resistance R can be reduced, resulting in a smaller voltage drop and lower power loss, thereby improving circuit efficiency and reducing heat generation. Simultaneously, the two NMOS transistors share the load current, halving the current carried by each individual transistor, which helps extend the device's lifespan and is particularly important in high-current applications.

[0056] When the power supply is connected with the correct polarity (positive terminal 101 is positive, negative terminal 102 is negative), the gates of the first NMOS transistor Q1 and the second NMOS transistor Q2 have a positive voltage difference (Vgs > Vth) relative to their sources, causing both NMOS transistors to conduct. Once the first NMOS transistor Q1 and the second NMOS transistor Q2 are conducting, current can flow from the positive terminal 101 through the power supply interface 103 to the load, and then back through the first NMOS transistor Q1 to the negative terminal 102, forming a complete power supply loop. The presence of the second NMOS transistor Q2 ensures a low-impedance path between the power supply interface 103 and the load, further improving efficiency. If the power supply polarity is reversed (positive terminal 101 is negative, negative terminal 102 is positive), the gates of the first NMOS transistor Q1 and the second NMOS transistor Q2 do not have sufficient positive voltage relative to their sources (Vgs < Vth), therefore neither NMOS transistor will conduct.

[0057] In other embodiments, the switching unit 300 can also be connected between the positive terminal and the power supply interface, with the negative terminal controlling the switching state, thus preventing the power supply circuit from being interrupted when the power supply is reversed. Of course, the implementation of the switching unit 300 will vary accordingly. Optionally, in... Figure 5 In this embodiment, the switching unit 300 includes a first PMOS transistor Q3, the gate of the first PMOS transistor Q3 is coupled to the negative terminal 102, the source of the first PMOS transistor Q3 is coupled to the positive terminal 101, and the drain of the first PMOS transistor Q3 is coupled to the power supply interface 103.

[0058] In some embodiments, when the power supply is connected with the correct polarity (positive terminal 101 is positive, negative terminal 102 is negative), the gate of the first PMOS transistor Q3 has a negative voltage difference relative to its source (Vgs < Vth, where Vth is the threshold voltage), causing the first PMOS transistor Q3 to conduct. Once the first PMOS transistor Q3 is turned on, current can flow from the positive terminal 101 through the PMOS transistor to the power supply interface 103, and then to the external load 200, forming a complete power supply loop. If the power supply polarity is reversed (positive terminal 101 is negative, negative terminal 102 is positive), the gate of the first PMOS transistor Q3 does not have a sufficient negative voltage relative to its source (Vgs > Vth), and the first PMOS transistor Q3 will not conduct. In some cases, using the first PMOS transistor Q3 can better isolate the power supply and the load, reducing the risk caused by misoperation.

[0059] Optionally, in Figure 6In the embodiment, the switch unit 300 further comprises a second PMOS Q4 connected between the source of the first PMOS Q3 and the positive polarity end 101, the second PMOS Q4 and the first PMOS Q3 share a drain, the gate of the second PMOS Q4 is coupled to the negative polarity end 102, and the source of the second PMOS Q4 is coupled to the positive polarity end 101.

[0060] In some embodiments, the use of two PMOSs in parallel can significantly reduce the total on-resistance R. When the power supply is connected with correct polarity (the positive polarity end 101 is positive and the negative polarity end 102 is negative), the gate of the first PMOS Q3 and the second PMOS Q4 has a negative voltage difference relative to their sources (Vgs < Vth, where Vth is the threshold voltage), so that both PMOSs are turned on. Once the first PMOS Q3 and the second PMOS Q4 are turned on, current can flow from the positive polarity end 101 through both PMOSs to the power supply interface 103 and then to the external load 200, forming a complete power supply loop. If the power supply is connected with reverse polarity (the positive polarity end 101 is negative and the negative polarity end 102 is positive), the gate of the first PMOS Q3 and the second PMOS Q4 does not have enough negative voltage relative to their sources (Vgs > Vth), so that both PMOSs are not turned on.

[0061] Optionally, in Figure 7 In the embodiment, when the switch unit 300 comprises an N-type transistor (such as NMOS or N-type triode, etc.), the power supply reverse connection protection circuit further comprises a switch control unit 700 connected between a pair of polarity ends and leading out a switch signal end outputting a switch signal corresponding to the voltage direction between a pair of polarity ends; the switch signal end is coupled to the control end of the N-type transistor to control the on-off of the N-type transistor. The switch control unit 700 is used to monitor the voltage direction between the polarity ends. Optionally, in Figure 8 In the embodiment, the switch control unit 700 comprises a resistance voltage dividing unit 401, both ends of which are coupled to a pair of polarity ends and at least one voltage dividing point leading out the switch signal end. The resistance voltage dividing unit 401 is composed of multiple resistors. Since the N-type transistor is high-level on, when the power supply is connected with correct polarity, the voltage dividing point between the resistance voltage dividing unit 401 has a high potential, so that the switch signal end outputs a high-level signal to the gate of the NMOS. This makes the NMOS turn on, and current can flow from the positive polarity end 101 through the power supply interface 103 to the load and then through the NMOS back to the negative polarity end 102, forming a complete power supply loop.

[0062] Optionally, in Figure 9 Or Figure 10In an embodiment, the reverse connection prevention circuit further comprises a first capacitor C1 connected in parallel with the voltage stabilizing diode D1. The first capacitor C1 is used for filtering and can buffer the load current variation, so that the output voltage is more stable, especially in the case of rapid load variation. When the input voltage suddenly rises, the first capacitor C1 can share the overvoltage impact with the voltage stabilizing diode D1, providing a double protection mechanism.

[0063] Further, the first capacitor C1 can also be connected in parallel with the resistance voltage dividing unit as shown. Figure 8

[0064] Optionally, in an embodiment, a resistance R is arranged between the power supply interface 103 connected to the external load 200 and the positive polarity end 101. The resistance R can limit the inrush current at startup to prevent excessive transient current from damaging sensitive elements or loads downstream. In the normal working state, the resistance R can help to share part of the current, reduce the burden of the switching unit 300 (such as NMOS tube), and prolong its service life. Figure 11 Figure 12 In an embodiment, a resistance R is arranged between the power supply interface 103 connected to the external load 200 and the positive polarity end 101. The resistance R can limit the inrush current at startup to prevent excessive transient current from damaging sensitive elements or loads downstream. In the normal working state, the resistance R can help to share part of the current, reduce the burden of the switching unit 300 (such as NMOS tube), and prolong its service life.

[0065] In another embodiment of the present disclosure, a power supply circuit is provided, which comprises the reverse connection prevention circuit as described in any of the above embodiments.

[0066] The above embodiments are only illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed by the present disclosure shall still be covered by the protection scope of the present disclosure.​​

Claims

1. A reverse connection prevention circuit for a power supply, characterized by comprising: The power supply reverse connection prevention circuit comprises: a pair of polarity terminals opposite to each other, forming a power supply interface between the pair of polarity terminals for connecting a circuit to at least one external load to form a power supply loop; a switch unit coupled between one of the pair of polarity terminals and the power supply interface, a control end of the switch unit being coupled to the other polarity terminal, configured to control the on-off of the power supply loop based on the voltage direction between the pair of polarity terminals; a voltage stabilizing diode, a positive end of the voltage stabilizing diode being coupled to the positive polarity terminal, and a negative end of the voltage stabilizing diode being coupled to the negative polarity terminal.

2. The reverse connection prevention circuit for power supply according to claim 1, wherein The switch unit comprises a first NMOS transistor, a gate of the first NMOS transistor being coupled to the positive polarity terminal, a drain of the first NMOS transistor being coupled to the negative polarity terminal, and a source of the first NMOS transistor being coupled to the power supply interface.

3. The reverse connection prevention circuit for power supply according to claim 2, wherein The switch unit further comprises a second NMOS transistor connected between the source of the first NMOS transistor and the power supply interface, a gate of the second NMOS transistor being coupled to the positive polarity terminal, the second NMOS transistor and the first NMOS transistor sharing a common source, and a drain of the second NMOS transistor being coupled to the power supply interface.

4. The reverse connection prevention circuit for power supply according to claim 1, wherein The switch unit comprises a first PMOS transistor, a gate of the first PMOS transistor being coupled to the negative polarity terminal, a source of the first PMOS transistor being coupled to the positive polarity terminal, and a drain of the first PMOS transistor being coupled to the power supply interface.

5. The reverse connection prevention circuit for power supply according to claim 4, wherein The switch unit further comprises a second PMOS transistor connected between the source of the first PMOS transistor and the positive polarity terminal, the second PMOS transistor and the first PMOS transistor sharing a common drain, a gate of the second PMOS transistor being coupled to the negative polarity terminal, and a source of the second PMOS transistor being coupled to the positive polarity terminal.

6. The reverse connection prevention circuit for power supply according to claim 1, wherein When the switch unit comprises an N-type transistor, the power supply reverse connection prevention circuit further comprises a switch control unit connected between the pair of polarity terminals and outputting a switch signal end with a switch signal corresponding to the voltage direction between the pair of polarity terminals; the switch signal end being coupled to a control end of the N-type transistor to control the on-off of the N-type transistor.

7. The reverse connection prevention circuit for power supply according to claim 6, wherein The switch control unit comprises: a resistance voltage dividing unit, two ends of the resistance voltage dividing unit being coupled to the pair of polarity terminals, and at least one voltage dividing point of the resistance voltage dividing unit being coupled to the switch signal end.

8. The reverse connection prevention circuit for power supply according to claim 1, wherein The power supply reverse connection prevention circuit further comprises a first capacitor connected in parallel with the voltage stabilizing diode.

9. The reverse connection prevention circuit for power supply according to claim 1, wherein A resistance is arranged between the power supply interface connected to the external load and the positive polarity terminal.

10. A power supply circuit, characterized by comprising: The power supply reverse connection prevention circuit comprises the power supply reverse connection prevention circuit according to any one of claims 1 to 9.

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