Overcurrent protection circuit

Abstract

The utility model discloses an overcurrent protection circuit which comprises a sampling unit, a comparison unit, a feedback unit and a control unit. The sampling unit comprises a current detection chip U2; the feedback unit comprises an optical coupler U1, and the interior of the optical coupler U1 is composed of a transmitting tube and an NPN transistor. The control unit comprises an MOS tube; the IP + end of the current detection chip U2 is connected in series with a power supply, and the IP-end of the current detection chip U2 is communicated with the drain electrode or the source electrode of the MOS tube; the VIO end of the current detection chip U2 is communicated with the input end of the comparison unit; the output end of the comparison unit is communicated with the transmitting tube, the emitting electrode of the NPN transistor is communicated with the grid electrode of the MOS tube, the collector electrode of the NPN transistor is communicated with a power supply, and the comparison unit can control the on-off of the optical coupler U1; the optical coupler U1 can control the on-off of the MOS tube; and the source electrode of the MOS tube is communicated with a load. And over-current protection of the circuit is realized.

Description

Technical Field

[0001] The present application relates to the technical field of circuit protection, and in particular to an overcurrent protection circuit. Background Art

[0002] As a core component of modern power conversion technology, switching power supplies have been widely used in various power consumption occasions. Whether the switching power supply can operate safely and stably is directly related to circuit safety, equipment safety and even personal safety. Therefore, in the design of switching power supplies, protection circuits are usually added to ensure the safe and stable operation of the power supply.

[0003] When a high-power DC / DC module has multiple outputs, the reliability of its internal components cannot be guaranteed when the output power exceeds its rated power. Therefore, corresponding overcurrent or short-circuit protection needs to be set in each branch of each DC module to prevent the entire DC / DC module from having no output due to a failure in one of the outputs, thereby affecting the normal output of other outputs. Utility Model Content

[0004] The embodiment of the present application provides an overcurrent protection circuit to solve the problem that when a high-power DC / DC module has multiple common outputs, if one output is short-circuited or has an overcurrent fault, the entire DC / DC module will have no output, thereby affecting the normal operation of other branches. The present application can effectively isolate the fault and implement overcurrent protection for the circuit.

[0005] The utility model embodiment provides an overcurrent protection circuit, including a sampling unit, a comparison unit, a feedback unit and a control unit; the sampling unit includes a current detection chip U2; the feedback unit includes an optical coupler U1, and the optical coupler U1 is composed of an emission tube and an NPN transistor; the control unit includes a MOS tube; the IP+ end of the current detection chip U2 is connected in series with a power supply, and the IP-end of the current detection chip U2 is connected to the drain or source of the MOS tube; the VIO end of the current detection chip U2 is connected to the input end of the comparison unit; the output end of the comparison unit is connected to the emission tube, the emitter of the NPN transistor is connected to the gate of the MOS tube, and the collector of the NPN transistor is connected to the power supply, and the comparison unit can control the on and off of the optical coupler U1; the optical coupler U1 can control the on and off of the MOS tube; the source of the MOS tube is connected to a load.

[0006] In a possible implementation, the comparison unit includes a resistor R6, a resistor R7, a resistor R8, a capacitor C3 and a TL431 unidirectional thyristor; the resistor R6, the resistor R7 and the resistor R8 are connected in series in sequence between the VIO terminal and the ground terminal of the current detection chip U2; the reference electrode of the TL431 unidirectional thyristor is connected between the resistor R7 and the resistor R8, the anode of the TL431 unidirectional thyristor is grounded, and the cathode of the TL431 unidirectional thyristor is connected to the transmitting tube; the capacitor C3 is connected in parallel between the reference electrode of the TL431 unidirectional thyristor and the anode of the TL431 unidirectional thyristor.

[0007] In a possible implementation, the feedback unit further includes a Zener diode D1, a resistor R1, a resistor R2, and a resistor R3; the resistor R1 is externally connected to a constant voltage power supply; the resistor R1 and the Zener diode D1 are connected in series in sequence, the resistor R2 is connected in parallel with the transmitting tube, one end of which is grounded, and the other end is connected in series with the Zener diode D1, the resistor R3 is connected in series between the collector of the NPN transistor and the power supply; the output end of the comparison unit is connected between the resistor R1 and the Zener diode D1.

[0008] In a possible implementation, the control unit further includes a resistor R4 and a zener diode D2; the resistor R4 and the zener diode D2 are both connected in parallel between the gate and the source of the MOS tube; the MOS tube includes a MOS tube Q1 and a MOS tube Q2; the MOS tube Q1 and the MOS tube Q2 are sequentially connected in series between the load and the IP-end of the current detection chip U2; the gates of the MOS tube Q1 and the MOS tube Q2 are both connected to the emitter of the NPN transistor.

[0009] In a possible implementation, the MOS transistor further includes a MOS transistor Q3 and a MOS transistor Q4; the MOS transistor Q3 is connected in parallel with the MOS transistor Q1, and the MOS transistor Q4 is connected in parallel with the MOS transistor Q2; and the gates of the MOS transistor Q3 and the MOS transistor Q4 are both connected to the emitter of the NPN transistor.

[0010] In a possible implementation, the feedback unit includes a resistor R6, a resistor R7, a resistor R8 and a comparator; the resistor R6, the resistor R7 and the resistor R8 are connected in series between the VIO terminal and the ground terminal of the current detection chip U2; the inverting input terminal of the comparator is connected between the resistor R7 and the resistor R8, the non-inverting input terminal of the comparator is connected to a 2.5V reference voltage, and the output terminal of the comparator is connected to the transmitting tube.

[0011] In a possible implementation, the sampling unit (3) further comprises a capacitor C1, a capacitor C2 and a resistor R5; one end of the capacitor C1 is connected to the VIO end of the current detection chip U2, and the other end thereof is grounded; one end of the capacitor C2 is connected to the VCC end of the current detection chip U2, and the other end thereof is grounded; one end of the resistor R5 is connected to the VCC end of the current detection chip U2, and the other end thereof is applied with a constant voltage to supply power to the current detection chip U2.

[0012] One or more technical solutions provided in the embodiments of the present utility model have at least the following technical effects or advantages:

[0013] The embodiment of the utility model adopts a sampling unit, a comparison unit, a feedback unit and a control unit. The sampling unit includes a current detection chip U2, the feedback unit includes an optical coupler U1, the optical coupler U1 is composed of a transmitting tube and an NPN transistor, and the control unit includes a MOS tube; the IP+ end of the current detection chip U2 is connected in series with the protection power supply, the IP- end of the current detection chip U2 is connected to the drain or source of the MOS tube, and the current is output to the source or drain of the MOS tube through the IP- end of the current detection chip U2, the VIO end of the current detection chip U2 is connected to the input end of the comparison unit, and the V The IO terminal outputs a voltage proportional to the current, and the comparison unit is used to determine whether this voltage is greater than 2.5V, thereby determining whether the current of the protection power supply exceeds the specified value; the output end of the comparison unit is connected to the transmitting tube, and the comparison unit outputs a signal to the transmitting tube, thereby controlling the on and off of the optocoupler U1, the emitter of the NPN transistor is connected to the gate of the MOS tube, and the collector of the NPN is connected to the protection power supply; the source of the MOS tube is connected to the load; the voltage across the gate and source of the MOS tube must exceed a certain voltage value to be turned on, the MOS tube is turned on, and the load is normally connected to the protection power supply; the MOS tube is turned off, and the load is normally disconnected from the protection power supply. This application effectively solves the problem that when a high-power DC / DC module has multiple common outputs, if one output is short-circuited or has an overcurrent fault, the entire DC / DC module will have no output, thereby affecting the normal operation of other branches. This application can effectively isolate faults and achieve overcurrent protection for the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1A circuit diagram of an overcurrent protection circuit provided in an embodiment of the present application.

[0016] Icon: 1-Feedback unit; 2-Comparison unit; 3-Sampling unit; 4-Control unit. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] In the description of the embodiments of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. The terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present utility model can be understood according to specific circumstances.

[0019] The utility model embodiment provides an overcurrent protection circuit, such as Figure 1 As shown, it includes a sampling unit 3, a comparison unit 2, a feedback unit 1 and a control unit 4; the sampling unit 3 includes a current detection chip U2; the feedback unit 1 includes an optical coupler U1, and the optical coupler U1 is composed of an emission tube and an NPN transistor; the control unit 4 includes a MOS tube; the IP+ end of the current detection chip U2 is connected in series with the power supply, and the IP-end of the current detection chip U2 is connected to the drain or source of the MOS tube; the VIO end of the current detection chip U2 is connected to the input end of the comparison unit 2; the output end of the comparison unit 2 is connected to the emission tube, the emitter of the NPN transistor is connected to the gate of the MOS tube, and the collector of the NPN transistor is connected to the power supply, the comparison unit 2 can control the on and off of the optical coupler U1, and the optical coupler U1 can control the on and off of the MOS tube; the source of the MOS tube is connected to the load.

[0020] Exemplarily, the current detection chip U2 uses a WCS series chip, such as WCS-50ABS, WCS100ABS, etc., and the optical coupler U1 uses ORPC-817D series components.

[0021] In the present application embodiment, Figure 1 As shown, the present application adopts a sampling unit 3, a comparison unit 2, a feedback unit 1 and a control unit 4. The input end of the sampling unit 3 is connected to the power supply, and the sampling unit 3 can convert the current of the protection power supply into a proportional voltage; the output end of the sampling unit 3 is connected to the comparison unit 2, and the comparison unit 2 can be used to determine whether the voltage is greater than 2.5V, thereby determining whether the current of the protection power supply exceeds the specified value; the output end of the comparison unit 2 is connected to the feedback unit 1, and the output end of the comparison unit 2 transmits the compared signal to the feedback unit 1 to control the on and off of the feedback unit 1; the feedback unit 1 is connected to the control unit 4, and the on and off signal of the feedback unit 1 can determine the on and off of the control unit 4, and the control unit 4 is connected to the load of the protection power supply. When the current of the protection power supply exceeds the specified value, the connection with the load is disconnected; when the current returns to normal, the connection with the load is restored, thereby realizing overcurrent hiccup protection.

[0022] When the protection power supply is in normal working state, the output voltage of the VIO terminal of the current detection chip U2 is less than 2.5V, the output terminal of the comparison unit 2 outputs a high level, and current passes through the transmitting tube, which can turn on the NPN transistor. The current of the NPN transistor passes from the collector through the emitter and then through the gate of the MOS tube. At this time, there is a voltage between the source of the MOS tube and the gate of the MOS tube that can turn on the MOS tube, and the MOS tube is turned on, so that the protection power supply is connected to the load.

[0023] When the protection power supply is in an overcurrent or short-circuit state, the output voltage of the VIO terminal of the current detection chip U2 is greater than 2.5V, the output terminal of the comparison unit 2 outputs a low level, the transmitting tube is not turned on, and no current passes through the NPN transistor. At this time, there is no voltage between the source of the MOS tube and the gate of the MOS tube that can turn on the MOS tube, and the MOS tube is cut off, thereby disconnecting the protection power supply from the load. When the current returns to normal, the connection with the load is restored to achieve overcurrent hiccup protection.

[0024] In the present application embodiment, Figure 1As shown, the comparison unit 2 includes a resistor R6, a resistor R7, a resistor R8, a capacitor C3 and a TL431 unidirectional thyristor; the resistor R6, the resistor R7 and the resistor R8 are connected in series between the VIO terminal and the ground terminal of the current detection chip U2 in sequence; the reference electrode of the TL431 unidirectional thyristor is connected between the resistor R7 and the resistor R8, the anode of the TL431 unidirectional thyristor is grounded, and the cathode of the TL431 unidirectional thyristor is connected to the transmitting tube; the capacitor C3 is connected in parallel between the reference electrode of the TL431 unidirectional thyristor and the anode of the TL431 unidirectional thyristor.

[0025] Exemplarily, resistors R6, R7 and R8 are all voltage-dividing resistors, wherein resistors R6 and R7 are connected in series to improve regulation accuracy, facilitate designers to design circuits according to their needs, and also improve the sensitivity of the entire overcurrent protection circuit.

[0026] For example, capacitor C3 can provide a bias current for TL431 unidirectional thyristor, and the internal reference voltage of TL431 unidirectional thyristor is 2.5V; when the current exceeds the specified value, the current detection chip U2 outputs the corresponding voltage value, and the resistors R6, R7 and R8 are selected so that after the voltage is divided by R6 and R7, the voltage across R8 is greater than the internal reference voltage of 2.5V of TL431 voltage regulator. At this time, the cathode of TL431 is at a low level, that is, the output end of the comparison unit 2 outputs a low level to the transmitting tube. At this time, the transmitting tube is not turned on, and no current passes through the NPN transistor. At this time, there is no voltage between the source of the MOS tube and the gate of the MOS tube that can turn on the MOS tube, and the MOS tube is cut off, so that the protection power supply is disconnected from the load, and when the current returns to normal, the connection with the load is restored.

[0027] Exemplarily, when the current is less than the specified value, the current detection chip U2 outputs a corresponding voltage value, so that after the voltage is divided by R6 and R7, the voltage across R8 is less than the internal reference voltage of 2.5V of the TL431 voltage regulator. At this time, the cathode of TL431 is at a high level, that is, the output end of the comparison unit 2 outputs a high level to the transmitting tube. At this time, the transmitting tube has current passing through it, which can turn on the NPN transistor. The current of the NPN transistor passes from the collector through the emitter and then through the gate of the MOS tube. At this time, there is a voltage between the source of the MOS tube and the gate of the MOS tube that can turn on the MOS tube, and the MOS tube is turned on, so that the protection power supply is connected to the load.

[0028] In the present application embodiment, Figure 1As shown, the feedback unit 1 also includes a voltage regulator diode D1, a resistor R1, a resistor R2 and a resistor R3; the resistor R1 is externally connected to a constant voltage power supply; the resistor R1 and the voltage regulator diode D1 are connected in series in sequence, the resistor R2 is connected in parallel with the transmitting tube, one end of which is grounded, and the other end is connected in series with the voltage regulator diode D1, and the resistor R3 is connected in series between the collector of the NPN transistor and the power supply; the output end of the comparison unit 2 is connected between the resistor R1 and the voltage regulator diode D1.

[0029] For example, the resistor R1 is connected to an external 5V voltage power supply; the voltage regulator diode D1 has a critical voltage value and plays a role in stabilizing the voltage in the circuit. When the cathode of TL431 is at a high level, the voltage regulator diode D1 is reversely broken down, and the current can be input through the resistor R1 and the voltage regulator diode D1 and flow through the transmitting tube. Due to the photoelectric effect, a current is generated at the base of the NPN transistor, so that the collector to the emitter of the NPN transistor is turned on, so that there is a voltage between the source of the MOS tube and the gate of the MOS tube that can turn on the MOS tube, and the MOS tube is turned on, thereby protecting the power supply and the load from being connected. Otherwise, the protection power supply and the load are cut off, which will not be repeated.

[0030] Exemplarily, since the rated current flowing through the transmitting tube in the optical coupler U1 is small, a resistor R2 is connected in parallel to the transmitting tube for current shunting; the optical coupler U1 can isolate the voltage signal at the transmitting tube end; wherein the resistor R3 is a voltage dividing resistor;

[0031] In the present application embodiment, Figure 1 As shown, the control unit 4 also includes a resistor R4 and a voltage regulator diode D2; the resistor R4 and the voltage regulator diode D2 are both connected in parallel between the gate and the source of the MOS tube; the MOS tube includes a MOS tube Q1 and a MOS tube Q2; the MOS tube Q1 and the MOS tube Q2 are sequentially connected in series between the load and the IP-end of the current detection chip U2; the gates of the MOS tube Q1 and the MOS tube Q2 are both connected to the emitter of the NPN transistor;

[0032] Exemplarily, the resistor R4 is a voltage-dividing resistor, and the voltage-stabilizing diode D2 is used to stabilize the voltage between the gate and the source of the MOS tube. After the optical coupler U1 is turned on, the resistor R4 and the resistor R3 are connected in series for voltage division, wherein the voltage that can be divided across the resistor R4 is set to 12V. At this time, the voltage between the source and the gate of the MOS tube Q1 and the MOS tube Q2 is 12V, and the MOS tube Q1 and the MOS tube Q2 are turned on, so that the protection power supply is connected to the load.

[0033] In the present application embodiment, Figure 1 As shown, the MOS transistor further includes a MOS transistor Q3 and a MOS transistor Q4; the MOS transistor Q3 is connected in parallel with the MOS transistor Q1, and the MOS transistor Q4 is connected in parallel with the MOS transistor Q2; the gates of the MOS transistor Q3 and the MOS transistor Q4 are both connected to the emitter of the NPN transistor.

[0034] For example, when the current is too large, in order to improve the reliability of the entire circuit operation, the MOS tube also includes a MOS tube Q3 and a MOS tube Q4. When one MOS tube is broken down, the other MOS tube can still provide overcurrent protection for the entire circuit. That is, when the current of the protection power source exceeds the specified value, the connection with the load is disconnected; when the current returns to normal, the connection with the load is restored, thereby achieving overcurrent hiccup protection.

[0035] In the embodiment of the present application, the comparison unit 2 includes a resistor R6, a resistor R7, a resistor R8 and a comparator; the resistors R6, R7 and R8 are sequentially connected in series between the VIO terminal and the ground terminal of the current detection chip U2; the inverting input terminal of the comparator is connected between the resistor R7 and the resistor R8, the non-inverting input terminal of the comparator is connected to a 2.5V reference voltage, and the output terminal of the comparator is connected to the transmitting tube;

[0036] In another possible embodiment, the comparison unit 2 can also use a comparator to control the on and off of the feedback unit 1. The inverting input terminal of the comparator is connected between the resistor R7 and the resistor R8, and the non-inverting input terminal of the comparator is connected to a 2.5V reference voltage. When the voltage between the resistor R7 and the resistor R8 is greater than 2.5V, the comparator outputs a low level. When the voltage between the resistor R7 and the resistor R8 is less than 2.5V, the comparator outputs a high level. The same working principle can be achieved by controlling the feedback unit 1 with the output terminal of the comparator.

[0037] In the present application embodiment, Figure 1 As shown, the sampling unit 3 also includes a capacitor C1, a capacitor C2 and a resistor R5; one end of the capacitor C1 is connected to the VIO end of the current detection chip U2, and the other end thereof is grounded; one end of the capacitor C2 is connected to the VCC end of the current detection chip U2, and the other end thereof is grounded; one end of the resistor R5 is connected to the VCC end of the current detection chip U2, and a constant voltage is applied to the other end thereof to power the current detection chip U2.

[0038] Exemplarily, capacitors C1 and C2 have a filtering function; resistor R2 is externally connected to a 5V voltage supply.

[0039] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0040] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. An overcurrent protection circuit, characterized in that: It comprises a sampling unit (3), a comparison unit (2), a feedback unit (1) and a control unit (4); The sampling unit (3) comprises a current detection chip U2; The feedback unit (1) comprises an optical coupler U1, wherein the optical coupler U1 is internally composed of a transmitting tube and an NPN transistor; The control unit (4) comprises a MOS tube; The IP+ terminal of the current detection chip U2 is connected in series with the power supply, and the IP- terminal of the current detection chip U2 is connected to the drain or source of the MOS tube; the VIO terminal of the current detection chip U2 is connected to the input terminal of the comparison unit (2); The output end of the comparison unit (2) is connected to the transmitting tube, the emitter of the NPN transistor is connected to the gate of the MOS tube, the collector of the NPN transistor is connected to the power supply, and the comparison unit (2) can control the on and off of the optical coupler U1; the optical coupler U1 can control the on and off of the MOS tube; The source of the MOS tube is connected to the load.

2. An overcurrent protection circuit according to claim 1, characterized in that: The comparison unit (2) comprises a resistor R6, a resistor R7, a resistor R8, a capacitor C3 and a TL431 unidirectional thyristor; The resistor R6, the resistor R7 and the resistor R8 are sequentially connected in series between the VIO terminal and the ground terminal of the current detection chip U2; The reference electrode of the TL431 unidirectional thyristor is connected between the resistor R7 and the resistor R8, the anode of the TL431 unidirectional thyristor is grounded, and the cathode of the TL431 unidirectional thyristor is connected to the transmitting tube; The capacitor C3 is connected in parallel between the reference electrode of the TL431 unidirectional thyristor and the anode of the TL431 unidirectional thyristor.

3. The overcurrent protection circuit according to claim 1, characterized in that: The feedback unit (1) further comprises a voltage stabilizing diode D1, a resistor R1, a resistor R2 and a resistor R3; The resistor R1 is externally connected to a constant voltage power supply; The resistor R1 and the voltage-stabilizing diode D1 are connected in series in sequence; the resistor R2 is connected in parallel with the transmitting tube with one end being grounded and the other end being connected in series with the voltage-stabilizing diode D1; the resistor R3 is connected in series between the collector of the NPN transistor and the power supply; and the output end of the comparison unit (2) is connected between the resistor R1 and the voltage-stabilizing diode D1.

4. The overcurrent protection circuit according to claim 1, characterized in that: The control unit (4) further comprises a resistor R4 and a voltage stabilizing diode D2; The resistor R4 and the voltage stabilizing diode D2 are connected in parallel between the gate and source of the MOS tube; The MOS tubes include a MOS tube Q1 and a MOS tube Q2; The MOS transistor Q1 and the MOS transistor Q2 are connected in series between the load and the IP-terminal of the current detection chip U2 in sequence; the gates of the MOS transistor Q1 and the MOS transistor Q2 are both connected to the emitter of the NPN transistor.

5. An overcurrent protection circuit according to claim 4, characterized in that: The MOS tubes also include a MOS tube Q3 and a MOS tube Q4; The MOS transistor Q3 is connected in parallel with the MOS transistor Q1, and the MOS transistor Q4 is connected in parallel with the MOS transistor Q2; The gates of the MOS transistor Q3 and the MOS transistor Q4 are both connected to the emitter of the NPN transistor.

6. The overcurrent protection circuit according to claim 1, characterized in that: The comparison unit (2) comprises a resistor R6, a resistor R7, a resistor R8 and a comparator; The resistor R6, the resistor R7 and the resistor R8 are sequentially connected in series between the VIO terminal and the ground terminal of the current detection chip U2; The inverting input terminal of the comparator is connected between the resistor R7 and the resistor R8, the non-inverting input terminal of the comparator is connected to a 2.5V reference voltage, and the output terminal of the comparator is connected to the transmitting tube.

7. The overcurrent protection circuit according to claim 1, characterized in that: The sampling unit (3) further comprises a capacitor C1, a capacitor C2 and a resistor R5; One end of the capacitor C1 is connected to the VCC end of the current detection chip U2, and the other end thereof is grounded; one end of the capacitor C2 is connected to the VIO end of the current detection chip U2, and the other end thereof is grounded; One end of the resistor R5 is connected to the VCC end of the current detection chip U2, and the other end thereof is applied with a constant voltage to supply power to the current detection chip U2.

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