Switching circuit, chip and electronic equipment

Abstract

The embodiment of the utility model provides a switch circuit, a chip and electronic equipment, the switch circuit comprises a switch module and an overcurrent judgment module, the overcurrent judgment module is connected with the switch module, and the overcurrent threshold of the switch module can be adjusted based on the resistance ratio through the connection of the overcurrent judgment module and the switch module. Therefore, the accuracy of the over-current threshold can be improved, and the accuracy of over-current protection is improved according to the over-current comparison result output by the current flowing through the switch module and the over-current threshold.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a switching circuit, a chip, and an electronic device. Background Art

[0002] In a switching circuit, a switch tube and a mirror tube are usually used to form a mirror structure, so that the current flowing through the switch tube is obtained through the mirror tube, and then the switch tube is protected from overcurrent based on the current flowing through the mirror tube.

[0003] However, the switch tube and the mirror tube constituting the mirror structure are prone to deviation in the current obtained through the mirror tube due to factors such as parameter mismatch, thereby reducing the accuracy of overcurrent judgment. Utility Model Content

[0004] In view of the above problems, embodiments of the present application provide a switching circuit, a chip, and an electronic device to solve the above technical problems.

[0005] In a first aspect, an embodiment of the present application provides a switching circuit, which includes a switching module and an overcurrent judgment module. The overcurrent judgment module is connected to the switching module. The overcurrent judgment module is used to adjust the overcurrent threshold of the switching module based on the resistance ratio, and output the overcurrent comparison result according to the current flowing through the switching module and the overcurrent threshold.

[0006] In a second aspect, an embodiment of the present application further provides a chip comprising the above-mentioned switching circuit.

[0007] In a third aspect, an embodiment of the present application further provides an electronic device, which includes a device body and the above-mentioned chip or switch circuit provided in the device body.

[0008] The switching circuit, chip, and electronic device provided in the embodiments of the present application are connected to the switching module via an overcurrent judgment module. The overcurrent threshold of the switching module can be adjusted based on the resistance ratio, and an overcurrent comparison result can be output based on the current flowing through the switching module and the overcurrent threshold, thereby improving the accuracy of overcurrent protection.

[0009] These and other aspects of the present application will become more readily apparent from the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1A first principle block diagram of a switching circuit provided in an embodiment of the present application is shown.

[0012] Figure 2 The schematic diagram of the overcurrent detection module is shown.

[0013] Figure 3 A principle block diagram of an overcurrent threshold setting unit is shown.

[0014] Figure 4 shows the circuit schematic of the negative feedback unit.

[0015] Figure 5 shows the circuit schematic of the mirror unit.

[0016] Figure 6 The schematic diagram of the circuit of the comparison unit and the impedance unit is shown.

[0017] Figure 7 A first circuit schematic diagram of the switch module is shown.

[0018] Figure 8 A second circuit schematic diagram of the switch module is shown.

[0019] Figure 9 A second principle block diagram of the switching circuit provided in an embodiment of the present application is shown.

[0020] Figure 10 shows the circuit schematic of the pull-down module.

[0021] Figure 11 A schematic diagram of a chip provided in an embodiment of the present application is shown.

[0022] Figure 12 A schematic diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0023] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0024] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0025] In the embodiments of the present application, it should be noted that, in this document, relational terms such as first and second, etc., are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0026] Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0027] In the description of the embodiments of this application, words such as "example" or "for example" are used to indicate an example, illustration, or description. Any embodiment or design described as "for example" or "for example" in the embodiments of this application is not to be construed as being preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to clearly present relative concepts.

[0028] In addition, in the embodiments of the present application, "plurality" refers to two or more. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two, or more. For example, "including at least one" means including one, two, or more, and does not limit which ones are included. For example, "including at least one of A, B, and C" means including A, B, C, A and B, A and C, B and C, or A, B, and C.

[0029] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0030] The switch circuit 100 provided in the embodiment of the present application can be used, but is not limited to, in the PD (Power Deliver) protocol as a VCONN switch. Figure 1As shown, the switch circuit 100 includes a switch module 10 and an overcurrent judgment module 20. The overcurrent judgment module 20 is connected to the switch module 10. By connecting the overcurrent judgment module 20 to the switch module 10, the overcurrent threshold of the switch module 10 can be adjusted based on the resistance ratio, and whether the switch module 10 has an overcurrent is determined based on the overcurrent comparison result between the current flowing through the switch module 10 and the overcurrent threshold, thereby improving the accuracy of the overcurrent protection.

[0031] The present application embodiment provides a switching circuit 100. Figures 1 to 10 ,like Figure 1 As shown, the switching circuit 100 includes a switching module 10 and an overcurrent judgment module 20. The overcurrent judgment module 20 is connected to the switching module 10. The overcurrent judgment module 20 is used to adjust the overcurrent threshold of the switching module 10 based on the resistance ratio, and output the overcurrent comparison result according to the current flowing through the switching module 10 and the overcurrent threshold.

[0032] It can be understood that the switching circuit 100 provided in the embodiment of the present application is connected to the switching module 10 through the overcurrent judgment module 20, and the overcurrent threshold of the switching module 10 can be adjusted based on the resistance ratio, which can improve the accuracy of the overcurrent threshold and output the overcurrent comparison result based on the current flowing through the switch module 10 and the overcurrent threshold, thereby improving the accuracy of the overcurrent protection.

[0033] It should be noted that the resistance ratio in this embodiment is not the ratio of two resistors directly connected together, but the ratio of two resistors electrically connected together through a mirror structure.

[0034] In one embodiment, Figure 2 As shown, the overcurrent judgment module 20 includes an overcurrent threshold setting unit 21 and a comparison unit 22. The overcurrent threshold setting unit 21 is connected to one end of the switch module 10, and the overcurrent threshold setting unit 21 is used to convert the overcurrent threshold into a corresponding voltage threshold; the first input end of the comparison unit 22 is connected to the output end of the overcurrent threshold setting unit 21, and the second input end of the comparison unit 22 is connected to the other end of the switch module 10. The comparison unit 22 is used to output an overcurrent comparison result according to the potential of the first input end and the potential of the second input end.

[0035] It should be noted that the overcurrent threshold setting unit 21 can adjust the overcurrent threshold by adjusting the resistance ratio. If the potential of the second input terminal is greater than or equal to the potential of the first input terminal, it indicates that an overcurrent has occurred in the switch module 10; and if the potential of the second input terminal is less than the potential of the first input terminal, it indicates that no overcurrent has occurred in the switch module 10.

[0036] In one embodiment, Figure 3As shown, the overcurrent threshold setting unit 21 includes a negative feedback unit 211, a mirror unit 212 and an impedance unit 213. The negative feedback unit 211 is used to obtain a first current based on the ratio of a reference voltage to a first resistance value; the mirror unit 212 is connected to the negative feedback unit 211, and is used to obtain a corresponding second current based on the first current; the impedance unit 213 is connected to the mirror unit 212, the first input end of the comparison unit 22 and one end of the switch module 10, and is used to convert the overcurrent threshold into a corresponding voltage threshold based on the second current; wherein the impedance unit 213 has a second resistance value, and the resistance ratio is the ratio of the second resistance value to the first resistance value.

[0037] It should be noted that the negative feedback unit 211 can self-generate a reference voltage and have a first resistance value. The first current can be equal to the second current to more accurately set the overcurrent threshold.

[0038] In one embodiment, Figure 4 As shown, the negative feedback unit 211 includes a reference voltage source 2111, an operational amplifier OP1, a first transistor M4, a first resistor R2, and a second resistor R1. The first input terminal of the operational amplifier OP1 is connected to the first output terminal of the reference voltage source 2111, and the power supply terminal of the operational amplifier OP1 is connected to the second output terminal of the reference voltage source 2111. The first electrode of the first transistor M4 is connected to the power supply terminal of the operational amplifier OP1 and the second output terminal of the reference voltage source 2111, respectively, and the control electrode of the first transistor M4 is connected to the output terminal of the operational amplifier OP1. One end of the first resistor R2 is connected to the second electrode of the first transistor M4, and the other end of the first resistor R2 is connected to the second input terminal of the operational amplifier OP1 and outputs the reference voltage. One end of the second resistor R1 is connected to the other end of the first resistor R2 and the second input terminal of the operational amplifier OP1, and the other end of the second resistor R1 is connected to the ground terminal GND. The second resistor R1 has a first resistance.

[0039] It should be noted that the first input terminal of the operational amplifier OP1 can be a non-inverting input terminal, and the second input terminal of the operational amplifier OP1 can be an inverting input terminal. The first output terminal of the reference voltage source 2111 can provide a stable reference voltage VREF, and the second output terminal of the reference voltage source 2111 can provide a stable power supply voltage VBAT.

[0040] Due to the structure of the reference voltage source 2111, a virtual short circuit can be formed between the first input terminal of the operational amplifier OP1 and the second input terminal of the operational amplifier OP1, so that the potential of the second input terminal of the operational amplifier OP1 is equal to the potential of the first input terminal of the operational amplifier OP1. Therefore, the first current flowing through the second resistor R1 can be recorded as VREF / R1, where VREF here represents the reference voltage and R1 represents the first resistance value of the second resistor R1.

[0041] The first transistor M4 can be a field-effect transistor or a bipolar junction transistor. For a field-effect transistor, the first electrode can be one of the source and drain electrodes, the second electrode can be the other of the source and drain electrodes, and the control electrode can be the gate electrode. For a field-effect transistor, the first electrode can be one of the source and drain electrodes, the second electrode can be the other of the source and drain electrodes, and the control electrode can be the gate electrode. For a bipolar junction transistor, the first electrode can be one of the collector and emitter electrodes, the second electrode can be the other of the collector and emitter electrodes, and the control electrode can be the base electrode.

[0042] In one embodiment, Figure 5 As shown, the mirror unit 212 includes a second transistor M5 and a third transistor M6. A first electrode of the second transistor M5 is connected to the ground terminal GND, and a second electrode of the second transistor M5 is connected to the control electrode of the second transistor M5 and the other end of the second resistor R1. A first electrode of the third transistor M6 is connected to the first electrode of the second transistor M5 and the ground terminal GND, a control electrode of the third transistor M6 is connected to the control electrode of the second transistor M5, and a second electrode of the third transistor M6 is connected to the impedance unit 213 and the first input terminal of the comparison unit 22.

[0043] It should be noted that the current flowing through the third transistor M6 can be recorded as the second current. The second transistor M5 can be the same as the third transistor M6, for example, both can be P-channel transistors, so that the second current is equal to the first current. The second transistor M5 or the third transistor M6 can be a field effect transistor or a bipolar junction transistor.

[0044] In one embodiment, Figure 6 As shown, the comparison unit 22 includes a comparator OP2, a second input end of the comparator OP2 is connected to the other end of the switch module 10, and an output end of the comparator OP2 is used to output the overcurrent judgment signal OCP_OUT; the impedance unit 213 includes a third resistor R3, one end of the third resistor R3 is connected to the second electrode of the third transistor M6 and the first input end of the comparator OP2, and the other end of the third resistor R3 is connected to one end of the switch module 10.

[0045] It should be noted that, in other embodiments, the impedance unit 213 may also be a series-parallel combination of multiple resistors to increase the adjustment method of the overcurrent threshold. The first input terminal of the comparator OP2 may be an inverting input terminal of the comparator OP2, and the second input terminal of the comparator OP2 may be a non-inverting input terminal of the comparator OP2.

[0046] In one embodiment, the first resistor R2 and / or the third resistor R3 are adjustable resistors, and the resistance ratio can be adjusted more flexibly to obtain a more accurate over-current threshold.

[0047] In one embodiment, Figure 7 As shown, the switch module 10 includes a fourth transistor M2 and a fifth transistor M3, a first electrode of the fourth transistor M2 is connected to the deep N-well of the fourth transistor M2 and the other end of the third resistor R3, and the P-well of the fourth transistor M2 is connected to the ground terminal GND; a first electrode of the fifth transistor M3 is connected to the deep N-well of the fifth transistor M3 and the second input terminal of the comparator OP2, a second electrode of the fifth transistor M3 is connected to the substrate of the fifth transistor M3, the second electrode of the fourth transistor M2 and the substrate of the fourth transistor M2, a control electrode of the fifth transistor M3 is connected to the control electrode of the fourth transistor M2 and the ground terminal GND, and a P-well of the fifth transistor M3 is connected to the ground terminal GND.

[0048] It should be noted that the fourth transistor M2 and the fifth transistor M3 can both be field-effect transistors or bipolar junction transistors. The connection mode of the fourth transistor M2 and the fifth transistor M3 forms a back-to-back connection mode, that is, the source of the fourth transistor M2 is connected to the source of the fifth transistor M3, the drain of the fourth transistor M2 is connected to the node VCONN in the PD protocol, and the drain of the fifth transistor M3 is connected to the node CC_IN in the PD protocol. Since the source of the transistor can withstand a low voltage, and the drain source and gate drain can withstand high voltage, this can avoid damage to the transistor and extend its service life. At the same time, this back-to-back connection mode makes the PN junctions of the two transistors reversed and cannot be turned on at the same time, avoiding the problem of leakage.

[0049] In other embodiments, the fourth transistor M2 and the fifth transistor M3 may also be N-channel laterally diffused metal oxide semiconductor (LDMOS) transistors.

[0050] In one embodiment, Figure 8As shown, the switch module 10 also includes a charge pump 11, a first Zener diode Z1 and a second Zener diode Z2. The charge pump 11 is connected between the first electrode of the fourth transistor M2 and the control electrode of the fourth transistor M2; the cathode of the first Zener diode Z1 is connected to the control electrode of the fourth transistor M2 and the control electrode of the fifth transistor M3; the cathode of the second Zener diode Z2 is connected to the anode of the first Zener diode Z1, and the anode of the second Zener diode Z2 is connected to the ground terminal GND.

[0051] It should be noted that the charge pump 11 may be a voltage-doubling charge pump 11 for improving the driving capability of the fourth transistor M2 and the fifth transistor M3. Two series-connected Zener diodes can clamp the gate potentials of the fourth transistor M2 and the fifth transistor M3. The clamping voltage of each Zener diode is approximately 5.75V, which can ensure that the gate voltage is not coupled to the high voltage while not affecting the normal operation of the charge pump 11.

[0052] In one embodiment, Figure 9 As shown, the switch circuit 100 also includes an overvoltage protection module 30, an OR gate OR, and a pull-down module 40. The overvoltage protection module 30 is connected to the second electrode of the fifth transistor M3. The overvoltage protection module 30 is used to output an overvoltage judgment signal OVP_OUT based on a comparison result of the potential of the second electrode of the fifth transistor M3 and the potential of the first input terminal of the operational amplifier OP1; the first input terminal of the OR gate OR is connected to the output terminal of the comparator OP2, and the second input terminal of the OR gate OR is connected to the output terminal of the overvoltage protection module 30; the control terminal of the pull-down module 40 is connected to the output terminal of the OR gate OR, and the pull-down module 40 is connected between the control terminal of the fourth transistor M2 and the ground terminal GND.

[0053] It should be noted that the overvoltage protection module 30 can provide overvoltage protection for the switch module 10. The overvoltage protection module 30 uses a reference voltage source 2111 to provide a reference voltage VREF. When the potential of the node CC_IN is greater than or equal to the reference voltage VREF, it indicates that an overvoltage has occurred in the switch module 10; when the potential of the node CC_IN is less than the reference voltage VREF, it indicates that no overvoltage has occurred in the switch module 10.

[0054] The OR gate OR can pull down the gate potentials of the fourth transistor M2 and the fifth transistor M3 to the potential of the ground terminal GND through the pull-down module 40 when at least one of overcurrent and overvoltage occurs, so as to turn off the fourth transistor M2 and the fifth transistor M3.

[0055] In one embodiment, Figure 10As shown, the pull-down module 40 includes a sixth transistor M1, a first electrode of the sixth transistor M1 is connected to the deep N-well of the sixth transistor M1 and the control electrode of the fourth transistor M2, a second electrode of the sixth transistor M1 is connected to the P-well of the sixth transistor M1, the substrate of the sixth transistor M1 and the ground terminal GND, and the control electrode of the sixth transistor M1 is connected to the output terminal of the OR gate OR.

[0056] It should be noted that the sixth transistor M1 may be a field effect transistor or a bipolar junction transistor. Specifically, the sixth transistor M1 may also be an N-channel laterally diffused metal oxide semiconductor (LDMOS) transistor.

[0057] In summary, the working principle of this application to make the overcurrent threshold more accurate is as follows:

[0058] First, the resistance values of the fourth transistor M2 and the fifth transistor M3 when they are turned on, ie, Ron, are determined through requirements and simulation.

[0059] Next, the overcurrent threshold of the current flowing through the fourth transistor M2 and the fifth transistor M3 is set to Ith.

[0060] Next, determine the parasitic impedances of the wiring and packaging (Bonding) at both ends of the switch, namely Rp1 and Rp2. Rp1 can be the parasitic impedance of the wiring and packaging between the drain of the fourth transistor M2 and the node VCONN. Rp2 can be the parasitic impedance of the wiring and packaging between the drain of the fifth transistor M3 and the node CC_IN.

[0061] The calculation formula of the flip threshold value Vth of the comparator OP2 is as follows:

[0062] Vth=VVCONN-Ith×(Rp1+Rp2+Ron) (1)

[0063] Here, VVCONN represents the potential of the node VCONN.

[0064] On the other hand, the reference voltage source 2111 can generate a reference current VREF / R1 after passing through an operational amplifier OP1 connected in a negative feedback manner. Therefore, the calculation formula of the flip threshold value Vth of the comparator OP2 can also be expressed as follows:

[0065] Vth=VVCONN-VREF÷R1×R3 (2)

[0066] Here, R1 represents the first resistance of the second resistor R1, and R3 represents the second resistance of the third resistor R3.

[0067] From equations (1) and (2), we can obtain equation (3) for determining the overcurrent threshold, Ith, expressed by the ratio of R3 to R1, as shown below:

[0068] Ith=VREF÷R1×R3÷(Rp1+Rp2+Ron) (3)

[0069] Since the resistance ratio can be matched through layout technology, the mismatch is very small. R3 and R1 can be adjusted to further improve the accuracy of the overcurrent threshold.

[0070] At the same time, the solution provided by the present application saves the mirror transistor (LDMOS) that forms a mirror structure with the switch transistor in the traditional technology. Among them, the second transistor M5 and the negative feedback unit 211 in the present application are reused original circuits. Compared with the traditional technology, the present application only adds a third transistor M6, and the power required to be realized by the third transistor M6 is smaller, thereby saving area.

[0071] The embodiment of the present application further provides a chip 200, such as Figure 11 As shown, the chip 200 includes the aforementioned switch circuit 100. The chip 200 is also called an integrated circuit (IC), and the chip 200 may be, but is not limited to, a SOC (System on Chip) chip or a SIP (System in Package) chip.

[0072] It can be understood that since the chip 200 provided in the embodiment of the present application includes the above-mentioned switching circuit 100, it can also be connected to the switching module 10 through the overcurrent judgment module 20, and the overcurrent threshold of the switching module 10 can be adjusted based on the resistance ratio, which can improve the accuracy of the overcurrent threshold and output the overcurrent comparison result based on the current flowing through the switching module 10 and the overcurrent threshold, thereby improving the accuracy of the overcurrent protection.

[0073] The embodiment of the present application also provides an electronic device 300, such as Figure 12As shown, the electronic device 300 includes a device body and the above-mentioned chip 200 or switch circuit 100 provided in the device body. The electronic device 300 can be, but is not limited to, a weight scale, a body fat scale, a nutrition scale, an infrared electronic thermometer, a pulse oximeter, a body composition analyzer, a mobile power supply, a wireless charger, a fast charger, a car charger, an adapter, a display, a USB (Universal Serial Bus) docking station, a stylus, a true wireless headset, a car central control panel, a car, a smart wearable device, a mobile terminal, and a smart home device. Smart wearable devices include, but are not limited to, smart watches, smart bracelets, and cervical massagers. Mobile terminals include, but are not limited to, smart phones, laptops, tablet computers, and POS (point of sales terminals). Smart home devices include, but are not limited to, smart sockets, smart rice cookers, smart sweepers, and smart lights.

[0074] It can be understood that since the electronic device 300 provided in the embodiment of the present application includes the above-mentioned switching circuit 100 or chip 200, it can also be connected to the switching module 10 through the overcurrent judgment module 20, and the overcurrent threshold of the switching module 10 can be adjusted based on the resistance ratio, which can improve the accuracy of the overcurrent threshold and output the overcurrent comparison result based on the current flowing through the switching module 10 and the overcurrent threshold, thereby improving the accuracy of the overcurrent protection.

[0075] The above are merely preferred embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present application. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A switching circuit, characterized in that: The switching circuit comprises: Switch module; An overcurrent judgment module is connected to the switch module, and is used to adjust the overcurrent threshold of the switch module based on the resistance ratio, and output an overcurrent comparison result according to the current flowing through the switch module and the overcurrent threshold.

2. The switching circuit according to claim 1, wherein: The overcurrent judgment module includes: an overcurrent threshold setting unit, the overcurrent threshold setting unit being connected to one end of the switch module and configured to convert the overcurrent threshold into a corresponding voltage threshold; A comparison unit, wherein a first input end of the comparison unit is connected to the output end of the overcurrent threshold setting unit, a second input end of the comparison unit is connected to the other end of the switch module, and the comparison unit is used to output the overcurrent comparison result according to the potential of the first input end and the potential of the second input end.

3. The switching circuit according to claim 2, wherein: The overcurrent threshold setting unit includes: a negative feedback unit, configured to obtain a first current according to a reference voltage and a first resistance; a mirror unit, the mirror unit being connected to the negative feedback unit, and configured to obtain a corresponding second current according to the first current; an impedance unit, the impedance unit being connected to the mirror unit, the first input terminal of the comparison unit, and one terminal of the switch module, respectively, and the impedance unit being configured to convert the overcurrent threshold into a corresponding voltage threshold according to the second current; The impedance unit has a second resistance value, and the resistance ratio is a ratio of the second resistance value to the first resistance value.

4. The switching circuit according to claim 3, wherein: The negative feedback unit comprises: Reference voltage source; an operational amplifier, wherein a first input terminal of the operational amplifier is connected to a first output terminal of the reference voltage source, and a power supply terminal of the operational amplifier is connected to a second output terminal of the reference voltage source; a first transistor, wherein a first electrode of the first transistor is connected to a power supply terminal of the operational amplifier and a second output terminal of the reference voltage source, and a control electrode of the first transistor is connected to an output terminal of the operational amplifier; a first resistor, one end of the first resistor being connected to the second electrode of the first transistor, and the other end of the first resistor being connected to the second input terminal of the operational amplifier and outputting the reference voltage; a second resistor, one end of the second resistor being connected to the other end of the first resistor and the second input end of the operational amplifier, the other end of the second resistor being connected to the ground end, and the second resistor having the first resistance.

5. The switching circuit according to claim 4, wherein: The mirror unit includes: a second transistor, wherein a first electrode of the second transistor is connected to the ground terminal, and a second electrode of the second transistor is connected to the control electrode of the second transistor and the other end of the second resistor; a third transistor, wherein a first electrode of the third transistor is connected to the first electrode of the second transistor and the ground end, a control electrode of the third transistor is connected to the control electrode of the second transistor, and a second electrode of the third transistor is connected to the impedance unit and the first input end of the comparison unit.

6. The switching circuit according to claim 5, wherein: The comparison unit includes a comparator, a second input end of the comparator is connected to the other end of the switch module, and an output end of the comparator is used to output an overcurrent judgment signal; The impedance unit includes a third resistor, one end of the third resistor is connected to the second electrode of the third transistor and the first input end of the comparator, and the other end of the third resistor is connected to one end of the switch module.

7. The switching circuit according to claim 6, wherein: The first resistor and / or the third resistor are adjustable resistors.

8. The switching circuit according to claim 6, wherein: The switch module includes: a fourth transistor, wherein a first electrode of the fourth transistor is connected to the deep N-well of the fourth transistor and the other end of the third resistor, and a P-well of the fourth transistor is connected to the ground; A fifth transistor, wherein the first electrode of the fifth transistor is connected to the deep N-well of the fifth transistor and the second input terminal of the comparator, the second electrode of the fifth transistor is connected to the substrate of the fifth transistor, the second electrode of the fourth transistor and the substrate of the fourth transistor, the control electrode of the fifth transistor is connected to the control electrode of the fourth transistor and the ground terminal, and the P-well of the fifth transistor is connected to the ground terminal.

9. The switching circuit according to claim 8, wherein: The switch module further includes: a charge pump connected between the first electrode of the fourth transistor and the control electrode of the fourth transistor; a first Zener diode, wherein a cathode of the first Zener diode is connected to the control electrode of the fourth transistor and the control electrode of the fifth transistor; A second Zener diode, wherein a cathode of the second Zener diode is connected to an anode of the first Zener diode, and an anode of the second Zener diode is connected to a ground terminal.

10. The switching circuit according to claim 8, wherein: The switching circuit further includes: an overvoltage protection module, the overvoltage protection module being connected to the second electrode of the fifth transistor, and configured to output an overvoltage determination signal based on a comparison result between the potential of the second electrode of the fifth transistor and the potential of the first input terminal of the operational amplifier; An OR gate, wherein a first input terminal of the OR gate is connected to the output terminal of the comparator, and a second input terminal of the OR gate is connected to the output terminal of the overvoltage protection module; A pull-down module, wherein the control end of the pull-down module is connected to the output end of the OR gate, and the pull-down module is connected between the control electrode of the fourth transistor and the ground end.

11. The switching circuit according to claim 10, wherein: The pull-down module includes a sixth transistor, a first electrode of the sixth transistor is connected to the deep N-well of the sixth transistor and the control electrode of the fourth transistor, a second electrode of the sixth transistor is connected to the P-well of the sixth transistor, the substrate of the sixth transistor and the ground end, and the control electrode of the sixth transistor is connected to the output end of the OR gate.

12. A chip, characterized in that: The chip includes the switching circuit according to any one of claims 1 to 11.

13. An electronic device, characterized in that: The electronic device includes a device body and the chip according to claim 12 provided in the device body.

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