A current detection circuit for a switching circuit

Abstract

The present invention discloses a current detection circuit of a switch circuit, and relates to the technical field of switch circuits. The detection circuit comprises a detection unit, and the detection unit comprises a first digital potentiometer, a second operational amplifier, a third operational amplifier, a fourth digital potentiometer, a fourth triode, a first resistor, a second resistor, and a fifth resistor; the third pin of the first digital potentiometer is connected to one end of the first resistor, the fifth pin of the first digital potentiometer is connected to one end of the second resistor, the output end of the second operational amplifier, the fifth pin of the fourth digital potentiometer, and the collector of the fourth triode are connected, and the twelfth pin of the first digital potentiometer and one end of the fifth resistor are connected to a power supply. The present invention can perform automatic voltage stabilization and overcurrent detection when the RC load changes, is applicable to RC loads of different resistance values, and automatically performs network matching when powered on to avoid errors.

Description

Technical Field

[0001] The present invention relates to the technical field of switch circuits, and in particular to a current detection circuit of a switch circuit. Background Art

[0002] The switching circuit is used to convert the power supply into a power supply voltage that can be used by the chip for power supply, and control the voltage within the voltage range required by the chip. The traditional approach is to use a buck circuit to complete the voltage regulation control of the chip power supply. However, since different chips can withstand different driving currents, when the load resistance changes, it needs to be limited. When the impedance tolerance and temperature influence of the circuit change, it will also cause regulation errors. Only the buck circuit cannot meet the regulation error problems caused by current detection and different influences while stabilizing the power supply. Summary of the invention

[0003] In view of the above technical problems, the object of the present invention is to provide a current detection circuit for a switch circuit, the detection circuit comprising a detection unit, the detection unit comprising a first digital potentiometer U1, a second operational amplifier U2, a third operational amplifier U3, a fourth digital potentiometer U4, a fourth transistor Q4, a first resistor R1, a second resistor R2, and a fifth resistor R5;

[0004] The third pin of the first digital potentiometer U1 is connected to one end of the first resistor R1, the fifth pin of the first digital potentiometer U1 is connected to one end of the second resistor R2, the output end of the second operational amplifier U2, the fifth pin of the fourth digital potentiometer U4, and the collector of the fourth transistor Q4 are connected, the twelfth pin of the first digital potentiometer U1, one end of the fifth resistor R5 and the power supply are connected, the inverting end of the second operational amplifier U2 is connected to the eleventh pin of the first digital potentiometer U1 and one end of the RC load, the inverting end of the third operational amplifier U3 is connected to the other end of the fifth resistor R5 and the twelfth pin of the fourth digital potentiometer U4, and the The output end of the third operational amplifier U3, the base of the fourth transistor Q4 and the Port end are connected, the sixth pin of the first digital potentiometer U1, the tenth pin of the first digital potentiometer U1, the fourteenth pin of the first digital potentiometer U1, the third pin of the fourth digital potentiometer U4, the sixth pin of the fourth digital potentiometer U4, the tenth pin of the fourth digital potentiometer U4, the eleventh pin of the fourth digital potentiometer U4, the fourteenth pin of the fourth digital potentiometer U4, the other end of the first resistor R1, the other end of the second resistor R2, the emitter of the fourth transistor Q4, the other end of the RC load, the tap end of the RC load and the ground end are connected.

[0005] Further, the detection unit also includes a fifth operational amplifier U5, a sixth thyristor U6, a seventh operational amplifier U7, a first transistor Q1, a second transistor Q2, a ninth resistor R9, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a first switch J1;

[0006] The inverting end of the fifth operational amplifier U5 is connected to the inverting end of the second operational amplifier U2, the output end of the fifth operational amplifier U5 is connected to one end of the thirteenth resistor R13 and the base of the second transistor Q2, the anode of the sixth thyristor U6 is connected to the collector of the second transistor Q2, the control electrode of the sixth thyristor U6, one end of the first switch J1 and the Port end are connected, the cathode of the sixth thyristor U6 is connected to one end of the ninth resistor R9 and the in-phase end of the seventh operational amplifier U7, and the inverting end of the seventh operational amplifier U7 is connected to the in-phase end of the third operational amplifier U3, The output end of the seventh operational amplifier U7 is connected to the base of the first transistor Q1, the collector of the first transistor Q1 is connected to the output end of the second operational amplifier U2, the emitter of the second transistor Q2 is connected to one end of the eleventh resistor R11 and one end of the twelfth resistor R12, the other end of the eleventh resistor R11 is connected to the power supply, the other end of the first switch J1 is connected to the third pin of the first digital potentiometer U1, the other end of the ninth resistor R9, the other end of the twelfth resistor R12, the other end of the thirteenth resistor R13, the emitter of the first transistor Q1 and the ground end are connected.

[0007] Further, the detection unit further includes an eighth operational amplifier U8, a third field effect transistor Q3, a fifteenth resistor R15, a sixteenth resistor R16, a first diode D1, and a first capacitor C1;

[0008] The in-phase end of the eighth operational amplifier U8 is connected to one end of the fifteenth resistor R15, one end of the sixteenth resistor R16, and one end of the first capacitor C1; the output end of the eighth operational amplifier U8 is connected to the gate of the third field effect transistor Q3; the source of the third field effect transistor Q3 and the other end of the fifteenth resistor R15 are connected to the power supply; the drain of the third field effect transistor Q3 is connected to the anode of the first diode D1; the cathode of the first diode D1 is connected to the Port end; the other end of the sixteenth resistor R16 and the other end of the first capacitor C1 are connected to the ground end.

[0009] Furthermore, the detection unit further includes a third resistor R3, a fourth resistor R4, a sixth resistor R6, and a seventh resistor R7;

[0010] One end of the third resistor R3 and one end of the sixth resistor R6 are connected to the power supply, the other end of the third resistor R3 is connected to one end of the fourth resistor R4 and the in-phase end of the second operational amplifier U2, the other end of the sixth resistor R6 is connected to one end of the seventh resistor R7 and the in-phase end of the third operational amplifier U3, and the other end of the fourth resistor R4 and the other end of the seventh resistor R7 are connected to the ground.

[0011] Furthermore, the detection unit further includes an eighth resistor R8 and a tenth resistor R10;

[0012] One end of the eighth resistor R8 is connected to the power supply, the other end of the eighth resistor R8 is connected to one end of the tenth resistor R10 and the in-phase terminal of the fifth operational amplifier U5, and the other end of the tenth resistor R10 is connected to the ground.

[0013] Furthermore, the detection unit further includes a fourteenth resistor R14;

[0014] One end of the fourteenth resistor R14 is connected to the gate of the third field effect transistor Q3, and the other end of the fourteenth resistor R14 is connected to the ground.

[0015] Furthermore, the sixth resistor R6, the fourth resistor R4 and the third resistor R3 are adjustable resistors.

[0016] Furthermore, it also includes an undervoltage unit, which is used to detect the power supply voltage of the RC end, and disconnect the power supply to the RC end when the power supply voltage is lower than a preset value of the undervoltage unit.

[0017] The beneficial effects of the present invention compared with the prior art are:

[0018] The present invention can automatically perform voltage stabilization and overcurrent detection when the RC load changes, is suitable for RC loads with different resistance values, and automatically performs network matching when powered on to avoid errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the prior art and the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 A schematic diagram of the circuit structure provided by the present invention. DETAILED DESCRIPTION

[0021] In order to make the objects and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific implementations of the present invention, and does not strictly limit the scope of protection specifically requested by the present invention.

[0022] The present invention discloses a current detection circuit of a switch circuit, the detection circuit comprises a detection unit, the detection unit comprises a first digital potentiometer U1, a second operational amplifier U2, a third operational amplifier U3, a fourth digital potentiometer U4, a fourth transistor Q4, a first resistor R1, a second resistor R2, and a fifth resistor R5;

[0023] The third pin of the first digital potentiometer U1 is connected to one end of the first resistor R1, the fifth pin of the first digital potentiometer U1 is connected to one end of the second resistor R2, the output end of the second operational amplifier U2, the fifth pin of the fourth digital potentiometer U4, and the collector of the fourth transistor Q4 are connected, the twelfth pin of the first digital potentiometer U1, one end of the fifth resistor R5 and the power supply are connected, the inverting end of the second operational amplifier U2 is connected to the eleventh pin of the first digital potentiometer U1 and one end of the RC load, the inverting end of the third operational amplifier U3 is connected to the other end of the fifth resistor R5 and the twelfth pin of the fourth digital potentiometer U4, and the The output end of the third operational amplifier U3, the base of the fourth transistor Q4 and the Port end are connected, the sixth pin of the first digital potentiometer U1, the tenth pin of the first digital potentiometer U1, the fourteenth pin of the first digital potentiometer U1, the third pin of the fourth digital potentiometer U4, the sixth pin of the fourth digital potentiometer U4, the tenth pin of the fourth digital potentiometer U4, the eleventh pin of the fourth digital potentiometer U4, the fourteenth pin of the fourth digital potentiometer U4, the other end of the first resistor R1, the other end of the second resistor R2, the emitter of the fourth transistor Q4, the other end of the RC load, the tap end of the RC load and the ground end are connected.

[0024] Specifically, the detection unit further includes a fifth operational amplifier U5, a sixth thyristor U6, a seventh operational amplifier U7, a first transistor Q1, a second transistor Q2, a ninth resistor R9, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and a first switch J1;

[0025] The inverting end of the fifth operational amplifier U5 is connected to the inverting end of the second operational amplifier U2, the output end of the fifth operational amplifier U5 is connected to one end of the thirteenth resistor R13 and the base of the second transistor Q2, the anode of the sixth thyristor U6 is connected to the collector of the second transistor Q2, the control electrode of the sixth thyristor U6, one end of the first switch J1 and the Port end are connected, the cathode of the sixth thyristor U6 is connected to one end of the ninth resistor R9 and the in-phase end of the seventh operational amplifier U7, and the inverting end of the seventh operational amplifier U7 is connected to the in-phase end of the third operational amplifier U3, The output end of the seventh operational amplifier U7 is connected to the base of the first transistor Q1, the collector of the first transistor Q1 is connected to the output end of the second operational amplifier U2, the emitter of the second transistor Q2 is connected to one end of the eleventh resistor R11 and one end of the twelfth resistor R12, the other end of the eleventh resistor R11 is connected to the power supply, the other end of the first switch J1 is connected to the third pin of the first digital potentiometer U1, the other end of the ninth resistor R9, the other end of the twelfth resistor R12, the other end of the thirteenth resistor R13, the emitter of the first transistor Q1 and the ground end are connected.

[0026] Specifically, the detection unit further includes an eighth operational amplifier U8, a third field effect transistor Q3, a fifteenth resistor R15, a sixteenth resistor R16, a first diode D1, and a first capacitor C1;

[0027] The in-phase end of the eighth operational amplifier U8 is connected to one end of the fifteenth resistor R15, one end of the sixteenth resistor R16, and one end of the first capacitor C1; the output end of the eighth operational amplifier U8 is connected to the gate of the third field effect transistor Q3; the source of the third field effect transistor Q3 and the other end of the fifteenth resistor R15 are connected to the power supply; the drain of the third field effect transistor Q3 is connected to the anode of the first diode D1; the cathode of the first diode D1 is connected to the Port end; the other end of the sixteenth resistor R16 and the other end of the first capacitor C1 are connected to the ground end.

[0028] Specifically, the detection unit further includes a third resistor R3, a fourth resistor R4, a sixth resistor R6, and a seventh resistor R7;

[0029] One end of the third resistor R3 and one end of the sixth resistor R6 are connected to the power supply, the other end of the third resistor R3 is connected to one end of the fourth resistor R4 and the in-phase end of the second operational amplifier U2, the other end of the sixth resistor R6 is connected to one end of the seventh resistor R7 and the in-phase end of the third operational amplifier U3, and the other end of the fourth resistor R4 and the other end of the seventh resistor R7 are connected to the ground.

[0030] Specifically, the detection unit further includes an eighth resistor R8 and a tenth resistor R10;

[0031] One end of the eighth resistor R8 is connected to the power supply, the other end of the eighth resistor R8 is connected to one end of the tenth resistor R10 and the in-phase terminal of the fifth operational amplifier U5, and the other end of the tenth resistor R10 is connected to the ground.

[0032] Specifically, the detection unit further includes a fourteenth resistor R14;

[0033] One end of the fourteenth resistor R14 is connected to the gate of the third field effect transistor Q3, and the other end of the fourteenth resistor R14 is connected to the ground.

[0034] Specifically, the sixth resistor R6, the fourth resistor R4 and the third resistor R3 are adjustable resistors.

[0035] Specifically, it also includes an undervoltage unit, which is used to detect the power supply voltage of the RC end. When the power supply voltage is lower than a preset value of the undervoltage unit, the power supply to the RC end is disconnected.

[0036] In one embodiment, the Port contact is grounded for a period of time when the circuit is powered on to initialize, so that the circuit performs network matching on RC loads with different resistance values, eliminating the factory tolerance of the potentiometer itself and the adjustment error caused by different impedance networks, wherein the first digital potentiometer U1 is used for RC load current limiting, the second operational amplifier U2 sets a voltage stabilization reference signal at the inverting end, and the inverting end and the eleventh pin of the first digital potentiometer U1 are connected to the port input when the ground is grounded, the third pin of the first digital potentiometer U1 is connected through the first resistor R1 loop, the third pin is the start pin, and the low level is valid, and the eleventh pin of the first digital potentiometer U1 is 1 / 4 of the tenth pin. The direction adjustment enters the high impedance state, the resistance of the first digital potentiometer U1 increases, and the voltage and current at the RC end are reset to the maximum current limit and the minimum supply voltage of the high impedance state of the first digital potentiometer U1. At the same time, the adjustment state of the fifth pin of the first digital potentiometer U1 stops at the fifth pin of the fourth digital potentiometer U4, and the third pin of the fourth digital potentiometer U4 is directly started by grounding. The fourth digital potentiometer U4 continues to adjust or is in a high impedance state before the first digital potentiometer U1 due to the factory tolerance and the change of the resistance network, and then it is divided with the fifth resistor R5 and input to the inverting end of the third operational amplifier U3 to complete the circuit initialization, and then the Port is disconnected. The second operational amplifier U2 outputs a signal to the second resistor R2 end compared with the voltage-stabilizing reference signal set at the in-phase end, and the Port is disconnected. The first digital potentiometer U1 enters a high-impedance state and changes to a low-impedance state during the adjustment process, until the voltage between the eleventh pin and the RC end of the first digital potentiometer U1 is the voltage-stabilizing reference signal set at the in-phase end of the second operational amplifier U2. At the same time, the adjustment of the first digital potentiometer U1 is synchronized to the fourth digital potentiometer U4. The fourth digital potentiometer U4 and the fifth resistor R5 are divided and input to the third operational amplifier U3. The in-phase end of the third operational amplifier U3 is used to set the maximum drive current reference signal voltage of the RC load. When the RC resistance value When the change occurs, if the third operational amplifier U3 has no output, the output of the second operational amplifier U2 is used to adjust the position of the eleventh pin of the first digital potentiometer U1 from the twelfth pin or the tenth pin so that the voltage at the RC end remains unchanged and is in a voltage-stabilizing state. If the current supply voltage exceeds the reference voltage signal of the maximum RC load drive current set at the in-phase end of the third operational amplifier U3 after the RC resistance value changes, the third operational amplifier U3 outputs a signal to the base of the fourth transistor Q4, and the first digital potentiometer U1 is called back to reduce the RC current until the RC overcurrent is lower than the maximum drive current set at the in-phase end of the third operational amplifier U3, and then the third operational amplifier U3 stops outputting and resets.

[0037] In one embodiment, another limiting method for overcurrent during voltage stabilization is provided. Compared with the first embodiment, reinitialization can be performed after overcurrent. After the impedance network changes at different temperatures, adjustment errors can be avoided to the maximum extent to prevent exceeding the maximum current limiting parameters. In the above embodiment, the connection between the fourth transistor Q4 and the third operational amplifier U3 is disconnected, and the output end of the third operational amplifier U3 is connected to the third pin of the first digital potentiometer U1 through the first switch J1. When the RC resistance value changes and overcurrent occurs under the voltage stabilization power supply of the first digital potentiometer U1, the third operational amplifier U3 The output signal is sent to the control electrode of the sixth thyristor U6. At the same time, the power supply at the end of the eleventh resistor R11 is connected to the emitter, base, thirteenth resistor R13 and ground loop of the second transistor Q2. The second transistor Q2 is turned on to supply power to the sixth thyristor U6. After the output of the third operational amplifier U3, the collector power supply of the second transistor Q2 is connected to the sixth thyristor U6, the ninth resistor R9 and the ground loop. The signal at the end of the ninth resistor R9 is fed back to the seventh operational amplifier U7. The comparison reference signal is set at the in-phase end of the seventh operational amplifier U7. The signal is greater than the cathode leakage voltage when the sixth thyristor U6 is turned off. Then, the seventh operational amplifier U7 outputs a signal to the base of the first transistor Q1, and the inverting terminal of the fifth operational amplifier U5 simultaneously samples the voltage of the eleventh pin of the first digital potentiometer U1. The non-inverting terminal of the fifth operational amplifier U5 is set to a reference signal that is greater than and close to the voltage at the RC terminal when the voltage is reset to the first digital potentiometer U1 in a high-impedance state. As the first transistor Q1 is turned on, the output terminal signal of the second operational amplifier U2 passes through the first transistor Q1 and the ground loop, and the first digital potentiometer U1 enters a high-impedance state from a low-impedance state. During the process, the eleventh pin of the first digital potentiometer U1 When the power supply of the pin and the RC end is lower than the reference signal voltage set at the in-phase end of the fifth operational amplifier U5, the fifth operational amplifier U5 outputs a signal to the base of the second transistor Q2. After the second transistor Q2 and the sixth thyristor U6 are turned off, the seventh operational amplifier U7 has no output, which turns off the first transistor Q1. The second operational amplifier U2 again feeds back the signal to the second resistor R2, and the first digital potentiometer U1 enters the low resistance state from the high resistance again and stabilizes the voltage and completes the reinitialization, waiting for the overcurrent to repeat the above process again, so as to avoid the adjustment error caused by the change of the resistance network and reduce the detection accuracy.

[0038] In one embodiment, in addition to enabling the ground signal of the Port through the upper chip, a method for automatic initialization when the circuit is powered on is provided, wherein the fifteenth resistor R15 and the first capacitor C1 are used to store energy when powered on, and the sixteenth resistor R16 is used to discharge when powered off. When the circuit is powered on, the power supply is input to the first capacitor C1 through the fifteenth resistor R15, and the voltage of the first capacitor C1 is gradually pulled up. The inverting end of the eighth operational amplifier U8 is set to a time reference voltage. When the voltage of the first capacitor C1 rises to the output of the eighth operational amplifier U8, the third field effect transistor Q3 is turned off. When the eighth operational amplifier U8 is turned off, the power supply signal of the source of the third field effect transistor Q3 is input to the base of the fourth transistor Q4 through the first diode D1, and the fourth transistor Q4 is turned on, and the first digital potentiometer U1 and the fourth digital potentiometer U4 enter a high impedance state. The reference voltage signals of the inverting end of the eighth operational amplifier U8, the non-inverting end of the second operational amplifier U2, and the non-inverting end of the third operational amplifier U3 can be set by corresponding connected voltage divider resistors in addition to the power supply and the upper control chip. When the inverting end of the eighth operational amplifier U8 shares the voltage divider resistor with the non-inverting end of the fifth operational amplifier U5, the RC time constant connected to the eighth operational amplifier U8 is adjusted to increase the time. The sixth resistor R6 can be set as an adjustable resistor to adjust the overcurrent parameter. The third resistor R3 or the fourth resistor R4 can be set as an adjustable resistor to adjust the voltage stabilization parameter. The fourteenth resistor R14 is used for the gate circuit of the third field effect tube Q3 to avoid the third field effect tube Q3 from failing to respond when the power is repeatedly turned on and off. The undervoltage unit is shown in the attached figure. The undervoltage unit includes a comparison circuit and a switch tube. The switch tube is set between the RC load and the eleventh pin of the first digital potentiometer U1. The comparison circuit sets the reference voltage and detects the power supply voltage of the RC load. When it is lower than the reference voltage, the switch tube is cut off to avoid undervoltage.

[0039] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A current detection circuit for a switching circuit, characterized in that: The detection circuit includes a detection unit, and the detection unit includes a first digital potentiometer, a second operational amplifier, a third operational amplifier, a fourth digital potentiometer, a fourth transistor, a first resistor, a second resistor, and a fifth resistor; The third pin of the first digital potentiometer is connected to one end of the first resistor, the fifth pin of the first digital potentiometer is connected to one end of the second resistor, the output end of the second operational amplifier, the fifth pin of the fourth digital potentiometer, and the collector of the fourth transistor are connected, the twelfth pin of the first digital potentiometer, one end of the fifth resistor and the power supply are connected, the inverting end of the second operational amplifier is connected to the eleventh pin of the first digital potentiometer and one end of the RC load, the inverting end of the third operational amplifier is connected to the other end of the fifth resistor and the twelfth pin of the fourth digital potentiometer, the output end of the third operational amplifier, the base of the fourth transistor and the Port end are connected, the sixth pin of the first digital potentiometer, the tenth pin of the first digital potentiometer, the fourteenth pin of the first digital potentiometer, the third pin of the fourth digital potentiometer, the sixth pin of the fourth digital potentiometer, the tenth pin of the fourth digital potentiometer, the eleventh pin of the fourth digital potentiometer, the fourteenth pin of the fourth digital potentiometer, the other end of the first resistor, the other end of the second resistor, the emitter of the fourth transistor, the other end of the RC load, the tap end of the RC load and the ground end are connected; The detection unit further includes a fifth operational amplifier, a sixth thyristor, a seventh operational amplifier, a first triode, a second triode, a ninth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a first switch; The inverting end of the fifth operational amplifier is connected to the inverting end of the second operational amplifier, the output end of the fifth operational amplifier is connected to one end of the thirteenth resistor and the base of the second transistor, the anode of the sixth thyristor is connected to the collector of the second transistor, the control electrode of the sixth thyristor, one end of the first switch and the Port end are connected, the cathode of the sixth thyristor is connected to one end of the ninth resistor and the non-inverting end of the seventh operational amplifier, the inverting end of the seventh operational amplifier is connected to the non-inverting end of the third operational amplifier, the output end of the seventh operational amplifier is connected to the base of the first transistor, the collector of the first transistor is connected to the output end of the second operational amplifier, the emitter of the second transistor is connected to one end of the eleventh resistor and one end of the twelfth resistor, the other end of the eleventh resistor is connected to the power supply, the other end of the first switch is connected to the third pin of the first digital potentiometer, the other end of the ninth resistor, the other end of the twelfth resistor, the other end of the thirteenth resistor, the emitter of the first transistor and the ground end are connected.

2. The current detection circuit of the switch circuit according to claim 1, characterized in that: The detection unit also includes an eighth operational amplifier, a third field effect transistor, a fifteenth resistor, a sixteenth resistor, a first diode, and a first capacitor; The in-phase end of the eighth operational amplifier is connected to one end of the fifteenth resistor, one end of the sixteenth resistor, and one end of the first capacitor; the output end of the eighth operational amplifier is connected to the gate of the third field effect transistor; the source of the third field effect transistor and the other end of the fifteenth resistor are connected to the power supply; the drain of the third field effect transistor is connected to the anode of the first diode; the cathode of the first diode is connected to the Port end; the other end of the sixteenth resistor, the other end of the first capacitor are connected to the ground end.

3. The current detection circuit of the switch circuit according to claim 1, characterized in that: The detection unit also includes a third resistor, a fourth resistor, a sixth resistor, and a seventh resistor; One end of the third resistor and one end of the sixth resistor are connected to the power supply, the other end of the third resistor is connected to one end of the fourth resistor and the in-phase end of the second operational amplifier, the other end of the sixth resistor is connected to one end of the seventh resistor and the in-phase end of the third operational amplifier, and the other end of the fourth resistor and the other end of the seventh resistor are connected to the ground.

4. The current detection circuit of the switch circuit according to claim 1, characterized in that: The detection unit also includes an eighth resistor and a tenth resistor; One end of the eighth resistor is connected to the power supply, the other end of the eighth resistor is connected to one end of the tenth resistor and the in-phase terminal of the fifth operational amplifier, and the other end of the tenth resistor is connected to the ground terminal.

5. The current detection circuit of the switch circuit according to claim 2, characterized in that: The detection unit also includes a fourteenth resistor; One end of the fourteenth resistor is connected to the gate of the third field effect transistor, and the other end of the fourteenth resistor is connected to the ground end.

6. The current detection circuit of the switch circuit according to claim 3, characterized in that: The sixth resistor, the fourth resistor and the third resistor are adjustable resistors.

7. The current detection circuit of the switch circuit according to claim 1, characterized in that: It also includes an undervoltage unit, which is used to detect the power supply voltage of the RC load. When the power supply voltage is lower than a preset value of the undervoltage unit, the power supply to the RC load is disconnected.

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