A high-power low-side driving device with current limiting and diagnostic functions

Abstract

The application discloses a high-power low-side driving device with current limiting and diagnostic functions. By arranging a driving circuit and a protection circuit, short circuit protection of a load circuit and a power supply end can be effectively realized, overload protection when driving a large current is realized, voltage data is sampled and outputted, so that an external diagnostic device can diagnose a load current, and the whole device adopts conventional components, is low in cost, and can be mass-produced and used.

Description

Technical Field

[0001] This application belongs to the field of DC low-side drive technology for automotive electronic and electrical products, specifically relating to a high-power low-side drive device with current limiting and diagnostic functions. Background Technology

[0002] Modern automotive electronic circuits employ numerous applications using high-side and low-side switches as drive outputs. These outputs operate within complex automotive electronic systems, requiring real-time monitoring of the circuit drive current to control circuit operation or implement functional logic. To achieve these objectives, and to ensure circuit reliability, the circuit must also possess hardware current limiting capabilities and overload or short-circuit protection. While some semiconductor companies now offer driver ICs with short-circuit protection, these are extremely expensive, resulting in significant cost overhead in cost-constrained applications. They are particularly suitable for applications with low integration requirements. Summary of the Invention

[0003] The purpose of this application is to provide a high-power low-side drive device with current limiting and diagnostic functions, which solves the problems existing in the prior art.

[0004] This application is achieved through the following technical solution:

[0005] A high-power low-side drive device with current limiting and diagnostic functions includes a control input circuit, a protection circuit, a holding circuit, a load circuit, a drive circuit, a sampling circuit, an amplification circuit, and a diagnostic output circuit.

[0006] The control input circuit is excited by an external signal to generate a control signal for the drive circuit, so as to control the opening and closing of the drive circuit according to the control signal.

[0007] The gate of the field-effect transistor in the driving circuit is excited by the control signal, which connects the drain and source of the field-effect transistor to connect the sampling circuit and the load circuit, so that the current of the load circuit is transmitted to the sampling circuit for sampling to obtain a voltage signal.

[0008] The amplification circuit amplifies the voltage signal sampled by the sampling circuit and transmits the amplified voltage signal to the base of the first transistor in the protection circuit and the diagnostic output circuit, respectively. The diagnostic output circuit outputs the amplified voltage signal to an external diagnostic device.

[0009] In the protection circuit, after the base of the first transistor receives an amplified voltage signal that exceeds its turn-on threshold, the gate of the field-effect transistor in the driving circuit is grounded to cut off the loop in which the load circuit is located, so that the load circuit can work within the limited current range.

[0010] In the holding circuit, the collector of the second transistor is connected to the connection point between the output terminal of the load circuit and the drain of the field-effect transistor. The base of the second transistor receives the control signal, and the emitter of the second transistor is connected to the base of the first transistor. When the loop containing the load circuit is cut off, the high level on the output terminal of the load circuit is continuously applied to the base of the first transistor, thereby continuously turning off the drive circuit and forming continuous protection.

[0011] In one possible implementation, the control input circuit includes transistors Q1 and Q2. The base of transistor Q1 receives excitation from an external signal, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the base of transistor Q2, the emitter of transistor Q2 is connected to the positive terminal VCC of the power supply, and the emitter of transistor Q2 is connected to its base through a resistor R2. The collector of transistor Q2 outputs a control signal.

[0012] In one possible implementation, the driving circuit includes a field-effect transistor Q5, the gate of which is connected to a control signal output from a control input circuit, the drain of which is connected to the output of a load circuit, the input of which is connected to the positive terminal VCC of a power supply, the source of which is connected to one end of a sampling circuit, and the other end of which is grounded.

[0013] In one possible implementation, the load circuit includes a load resistor RL1, the input of which is connected to the positive terminal VCC of the power supply, and the output of which is connected to the drain of the field-effect transistor Q5.

[0014] In one possible implementation, the sampling circuit includes a sampling resistor R11, one end of which is connected to the source of the field-effect transistor Q5, and the other end of which is grounded.

[0015] In one possible implementation, the amplification circuit includes an amplifier U1, the non-inverting input of which is connected to one end of the sampling circuit R11 to amplify the voltage signal sampled by the sampling resistor R11; the output of the amplifier U1 transmits the amplified voltage signal to the base of the first transistor in the protection circuit and the diagnostic output circuit, respectively, and the diagnostic output circuit outputs the amplified voltage signal to an external diagnostic device.

[0016] In one possible implementation, the protection circuit includes a transistor Q3, which serves as the first transistor. The collector of transistor Q3 is connected to the gate of field-effect transistor Q5, the emitter of transistor Q3 is grounded, and the base of transistor Q3 receives the voltage signal output by the amplifier circuit. When the voltage signal is greater than the turn-on voltage of transistor Q3, transistor Q3 turns on, grounding the gate of field-effect transistor Q5, thereby making the gate voltage of field-effect transistor Q5 zero, cutting off the loop containing the load circuit, and allowing the load circuit to operate within a limited current range.

[0017] In one possible implementation, a diode D5 is provided between the base of the first transistor and the output terminal of the amplifier U1. The anode of the diode D5 is connected to the output terminal of the amplifier U1, and the cathode of the diode D5 is connected to the base of the first transistor to prevent short circuit caused by the backlash of the voltage signal output by the second transistor in the holding circuit.

[0018] In one possible implementation, the holding circuit includes a transistor Q4, a resistor R6, a grounding capacitor C1, and a Zener diode D4. Transistor Q4 serves as a second transistor, with its collector connected to the drain of a field-effect transistor Q5, its emitter connected to the base of a first transistor, and its base connected to the anode of the Zener diode D4. The cathode of the Zener diode D4 is connected to both the grounding capacitor C1 and one end of the resistor R6. The other end of the resistor R6 receives a control signal. When the control signal is applied to the base of transistor Q4, and the field-effect transistor Q5 is turned off, transistor Q4 turns on, continuously applying a high-level signal from the load circuit output to the base of the first transistor, thereby continuously turning off the drive circuit and providing continuous protection.

[0019] In one possible implementation, the diagnostic output circuit includes a resistor R16 and a grounding capacitor C4. One end of the resistor R16 is connected to the output terminal of the amplifier U1 to receive the amplified voltage signal, and the other end of the resistor R16 outputs the amplified voltage signal to an external diagnostic device. The other end of the resistor R16 is also connected to the grounding capacitor C4 to filter the output signal.

[0020] This application provides a high-power low-side drive device with current limiting and diagnostic functions. By setting up a drive circuit and a protection circuit, it can effectively protect the load circuit and the power supply terminal from short circuits, and realize overload protection when the drive current is high. It also samples and outputs voltage data so that external diagnostic equipment can diagnose the load current. The electronic components used in the entire device are all conventional components, which are low in cost and can be mass-produced and used. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the exemplary embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0022] Figure 1 This is a structural block diagram of a high-power low-side drive device with current limiting and diagnostic functions provided in an embodiment of this application.

[0023] Figure 2 This is a circuit diagram of a high-power low-side drive device with current limiting and diagnostic functions, provided as an embodiment of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0025] Example 1

[0026] like Figure 1 and Figure 2 As shown in the embodiments, this application provides a high-power low-side drive device with current limiting and diagnostic functions, including a control input circuit, a protection circuit, a holding circuit, a load circuit, a drive circuit, a sampling circuit, an amplification circuit, and a diagnostic output circuit.

[0027] The control input circuit, excited by an external signal, generates a control signal for the drive circuit, which in turn controls the drive circuit to turn on and off. For example, when the input level is 1, the drive circuit is on; when the input level is 0, the drive circuit is off.

[0028] In the driving circuit, the gate of the field-effect transistor (FET) is excited by the control signal, which connects the drain and source of the FET to enable the sampling circuit and the load circuit to conduct. This allows the current from the load circuit to be transferred to the sampling circuit for sampling, resulting in a voltage signal. When the FET is on, it continuously outputs power below the current limit; when the FET is off, it cuts off the current flowing through the load circuit, keeping the circuit in a closed state.

[0029] It primarily uses a sampling resistor as a sensor to convert the current signal flowing through the loop into a voltage signal. By monitoring the voltage in the sampling circuit, the amount of current in the loop can be diagnosed.

[0030] The amplifier circuit amplifies the voltage signal sampled by the sampling circuit and transmits the amplified voltage signal to the base of the first transistor in the protection circuit and the diagnostic output circuit, respectively. The diagnostic output circuit then outputs the amplified voltage signal to an external diagnostic device.

[0031] When the base of the first transistor in the protection circuit receives an amplified voltage signal that exceeds its turn-on threshold, it grounds the gate of the field-effect transistor in the drive circuit to cut off the loop containing the load circuit, so that the load circuit can operate within the limited current range.

[0032] The collector of the second transistor in the circuit is connected to the connection point between the output terminal of the load circuit and the drain of the field-effect transistor. The base of the second transistor receives the control signal, and the emitter of the second transistor is connected to the base of the first transistor. When the loop containing the load circuit is cut off, the high level on the output terminal of the load circuit is continuously applied to the base of the first transistor, thereby continuously turning off the drive circuit and forming continuous protection.

[0033] In one possible implementation, the control input circuit includes transistors Q1 and Q2. The base of transistor Q1 receives excitation from an external signal, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the base of transistor Q2, the emitter of transistor Q2 is connected to the positive terminal VCC of the power supply, and the emitter of transistor Q2 is connected to its base through a resistor R2. The collector of transistor Q2 outputs a control signal.

[0034] Optionally, the base of transistor Q1 is connected to one end of resistor R1, and the other end of resistor R1 receives the excitation of an external signal. The base of transistor Q1 is also connected to grounding resistor R3. The collector of transistor Q1 is connected to the base of transistor Q2 through resistor R4. The collector of transistor Q2 is also connected to grounding resistor R5.

[0035] In one possible implementation, the driving circuit includes a field-effect transistor Q5. The gate of the field-effect transistor Q5 is connected to the control signal output by the control input circuit. The drain of the field-effect transistor Q5 is connected to the output terminal of the load circuit. The input terminal of the load circuit is connected to the positive terminal VCC of the power supply. The source of the field-effect transistor Q5 is connected to one end of the sampling circuit, and the other end of the sampling circuit is grounded.

[0036] Optionally, the driving circuit also includes a resistor R7, a diode D2, and a Zener diode D3. One end of the resistor R7 is connected to the gate of the field-effect transistor Q5, and the other end of the resistor R7 is connected to the control signal output by the control input circuit. The anode of the Zener diode D3 is connected to the source of the field-effect transistor Q5 and one end of the sampling resistor R11. The cathode of the Zener diode D3 is connected to the gate of the field-effect transistor Q5, the collector of the transistor Q3, one end of the resistor R7, and the anode of the diode D2. The anode of the diode D2 is connected to the collector of the transistor Q2 and the grounding resistor R5.

[0037] In one possible implementation, the load circuit includes a load resistor RL1, the input terminal of which is connected to the positive terminal VCC of the power supply, and the output terminal of which is connected to the drain of the field-effect transistor Q5.

[0038] In one possible implementation, the sampling circuit includes a sampling resistor R11, one end of which is connected to the source of the field-effect transistor Q5, and the other end of which is grounded.

[0039] It is worth noting that, in this embodiment, grounding is equivalent to connecting to the negative terminal of the power supply, thereby forming a load circuit so that the collector of transistor Q2 can control the conduction and cutoff of the load circuit.

[0040] In one possible implementation, the amplification circuit includes an amplifier U1, the non-inverting input of which is connected to one end of the sampling circuit R11 to amplify the voltage signal sampled by the sampling resistor R11. The output of the amplifier U1 transmits the amplified voltage signal to the base of the first transistor in the protection circuit and to the diagnostic output circuit, respectively, and the diagnostic output circuit outputs the amplified voltage signal to an external diagnostic device.

[0041] Optionally, the inverting input terminal of amplifier U1 is connected to grounding resistor R12, one end of resistor R14, and one end of capacitor C2, respectively. The other end of amplifier U1 is connected to the other end of capacitor C2, one end of resistor R14, grounding resistor R15, the negative terminal of Zener diode D6 in the protection circuit, and one end of resistor R16 in the diagnostic output circuit, respectively.

[0042] In one possible implementation, the protection circuit includes a transistor Q3, which serves as the first transistor. The collector of transistor Q3 is connected to the gate of field-effect transistor Q5, the emitter of transistor Q3 is grounded, and the base of transistor Q3 receives the voltage signal output from the amplifier circuit. When the voltage signal is greater than the turn-on voltage of transistor Q3, transistor Q3 turns on, grounding the gate of field-effect transistor Q5, thereby making the gate voltage of field-effect transistor Q5 zero, cutting off the loop containing the load circuit, and causing the load circuit to operate within a limited current range.

[0043] In one possible implementation, a diode D5 is provided between the base of the first transistor and the output terminal of the amplifier U1. The anode of the diode D5 is connected to the output terminal of the amplifier U1, and the cathode of the diode D5 is connected to the base of the first transistor to prevent short circuit caused by the backlash of the voltage signal output by the second transistor in the holding circuit.

[0044] Optionally, the protection circuit may also include a Zener diode D6, a grounding resistor R8, and a resistor R10 connected together. The positive terminal of the Zener diode D6 is connected to the positive terminal of the diode D5. The negative terminal of the diode D5 is connected to one end of the resistor R10, the grounding resistor R9 in the holding circuit, and the emitter of the transistor Q4. The other end of the resistor R10 is connected to the base of the transistor Q3 and the grounding resistor R8.

[0045] In one possible implementation, the holding circuit includes a transistor Q4, a resistor R6, a grounding capacitor C1, and a Zener diode D4. Transistor Q4 serves as the second transistor, with its collector connected to the drain of the field-effect transistor Q5, its emitter connected to the base of the first transistor, and its base connected to the anode of the Zener diode D4. The cathode of the Zener diode D4 is connected to both the grounding capacitor C1 and one end of the resistor R6. The other end of the resistor R6 receives the control signal. When the control signal is applied to the base of transistor Q4, and the field-effect transistor Q5 is turned off, transistor Q4 turns on, continuously applying a high-level signal from the load circuit output to the base of the first transistor, thereby continuously turning off the drive circuit and providing continuous protection.

[0046] Optionally, the holding circuit also includes a diode D1 and a grounding resistor R9. The positive terminal of the diode D1 is connected to the negative terminal of the Zener diode D4, one end of the resistor R6, and the grounding capacitor C1, respectively. The negative terminal of the diode D1 is connected to the other end of the resistor R6.

[0047] In one possible implementation, the diagnostic output circuit includes a resistor R16 and a grounding capacitor C4. One end of the resistor R16 is connected to the output of the amplifier U1 to receive the amplified voltage signal, and the other end of the resistor R16 outputs the amplified voltage signal to an external diagnostic device. The other end of the resistor R16 is also connected to the grounding capacitor C4 to filter the output signal.

[0048] The working principle of this application is as follows:

[0049] (1) Normal working principle

[0050] When the IN control terminal is high, the control input circuit is turned on. The power supply (the control signal input to the drive circuit) is applied to the gate of the field-effect transistor Q5 in the drive circuit through the transistor Q2 and the resistor R7, turning on the field-effect transistor Q5. The power supply forms a load loop through the load RL1, the field-effect transistor Q5 and the sampling resistor R11, and the drive circuit is turned on and driven.

[0051] During the opening process of the aforementioned driving circuit, due to the presence of capacitor C1 in the holding circuit, the conduction of transistor Q4 is delayed compared to that of field-effect transistor Q5. When field-effect transistor Q5 is turned on, the drain voltage of field-effect transistor Q5 is low, and the collector voltage of transistor Q4 is low. After transistor Q4 is turned on, transistor Q3 is turned off because the base voltage of transistor Q3 in the protection circuit is at a low level.

[0052] After the aforementioned drive circuit is turned on, the drive current flows through the sampling resistor R11. The sampling resistor R11 converts the flowing drive current into a voltage signal. The magnitude of the voltage across the sampling resistor R11 reflects the load magnitude flowing through the circuit. This voltage signal is amplified by the amplifier circuit and then input to the diagnostic output circuit and protection circuit.

[0053] (2) The load output terminal OUT is short-circuited to the power supply.

[0054] When operating normally, MOSFET Q5 is turned on. However, when a short circuit occurs between the load output terminal OUT (the end where the load resistor RL1 is connected to the drain of MOSFET Q5) and the positive terminal VCC of the power supply, since transistor Q4 is turned on and the base of transistor Q3 is at a high level, transistor Q3 is turned on. The gate of MOSFET Q5 is pulled down to ground through transistor Q3, and MOSFET Q5 is turned off, thus achieving short-circuit protection for the power supply at the output terminal.

[0055] (3) Output circuit current overload

[0056] Under normal operating conditions, transistor Q2 is turned on. However, when the load output terminal OUT is overloaded, the voltage across sampling resistor R11 rises. This voltage signal is amplified by amplifier U1 and then output. When the amplified voltage signal is higher than V... D6 +V D5 +V 三极管Q3be When transistor Q3 is turned on, the gate of MOSFET Q5 is pulled down to ground through transistor Q3, and MOSFET Q5 is turned off, thus achieving short-circuit protection for the power supply at the output terminal. Wherein, V D6 This indicates the voltage across diode D6, in V. D5 This indicates the voltage across diode D5, in V. 三极管Q3be This represents the forward voltage of transistor Q2.

[0057] After the aforementioned protection takes effect, the drain voltage of MOSFET Q5 increases due to its cutoff. Since transistor Q4 is in the conducting state, the base voltage of transistor Q3 remains high, and transistor Q3 continues to conduct, keeping the protection circuit operational. Because MOSFET Q5 is cut off, the output signal of amplifier U1 is low, losing control over transistor Q3. Diode D5 is used to prevent short circuits caused by signal backflow from transistor Q4 when the amplifier U1 output is 0.

[0058] (4) Other circuit descriptions

[0059] In this circuit, resistor R6, Zener diode D4, and grounding capacitor C1 work together to slow down the conduction of transistor Q4 compared to MOSFET Q5. The delay time primarily depends on the protection time requirement for MOSFET Q5. The charging speed can be adjusted by modifying the parameters of resistor R6 and grounding capacitor C1, and the start-up threshold can be adjusted by modifying the Zener diode D4. It's worth noting that while no specific parameters are explicitly given in the circuit, they can be adjusted as needed to match the circuit to the required power output protection.

[0060] This application can be applied to high-current operating applications. Parameters can be adjusted according to the actual drive power to reproduce circuit function for direct application. The device features current limiting, providing overload protection against high current. It also features load short-circuit protection, ensuring protection against power supply short circuits at the output. It can be applied to various types of loads. The current limiting is adjustable; the current threshold and / or amplification factor can be adjusted according to the load capacity of the driving MOSFET to achieve current limiting capability. The device has diagnostic outputs, making it suitable for applications requiring load detection. It is practical for high-current applications, applications with low integration requirements, and applications with cost constraints.

[0061] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A high-power low-side driver device with current limiting and diagnostic functions, characterized in that, It includes control input circuits, protection circuits, holding circuits, load circuits, drive circuits, sampling circuits, amplification circuits, and diagnostic output circuits; The control input circuit is excited by an external signal to generate a control signal for the drive circuit, so as to control the opening and closing of the drive circuit according to the control signal. The gate of the field-effect transistor in the driving circuit is excited by the control signal, which connects the drain and source of the field-effect transistor to connect the sampling circuit and the load circuit, so that the current of the load circuit is transmitted to the sampling circuit for sampling to obtain a voltage signal. The amplification circuit amplifies the voltage signal sampled by the sampling circuit and transmits the amplified voltage signal to the base of the first transistor in the protection circuit and the diagnostic output circuit, respectively. The diagnostic output circuit outputs the amplified voltage signal to an external diagnostic device. In the protection circuit, after the base of the first transistor receives an amplified voltage signal that exceeds its turn-on threshold, the gate of the field-effect transistor in the driving circuit is grounded to cut off the loop in which the load circuit is located, so that the load circuit can work within the limited current range. In the holding circuit, the collector of the second transistor is connected to the connection point between the output terminal of the load circuit and the drain of the field-effect transistor. The base of the second transistor receives the control signal, and the emitter of the second transistor is connected to the base of the first transistor. When the loop containing the load circuit is cut off, the high level on the output terminal of the load circuit is continuously applied to the base of the first transistor, thereby continuously turning off the drive circuit and forming continuous protection. The driving circuit includes a field-effect transistor Q5. The gate of the field-effect transistor Q5 is connected to the control signal output by the control input circuit. The drain of the field-effect transistor Q5 is connected to the output terminal of the load circuit. The input terminal of the load circuit is connected to the positive terminal VCC of the power supply. The source of the field-effect transistor Q5 is connected to one end of the sampling circuit, and the other end of the sampling circuit is grounded. The holding circuit includes a transistor Q4, a resistor R6, a grounding capacitor C1, and a Zener diode D4. Transistor Q4 serves as the second transistor. The collector of transistor Q4 is connected to the drain of MOSFET Q5, and the emitter of transistor Q4 is connected to the base of the first transistor. The base of transistor Q4 is connected to the anode of Zener diode D4, and the cathode of Zener diode D4 is connected to both the grounding capacitor C1 and one end of resistor R6. The other end of resistor R6 receives a control signal. When the control signal is applied to the base of transistor Q4, and MOSFET Q5 is turned off, transistor Q4 turns on, continuously applying a high-level signal from the load circuit output to the base of the first transistor, thereby continuously turning off the drive circuit and providing continuous protection.

2. The low-side driver with current limit and diagnostic function according to claim 1, wherein, The control input circuit includes transistors Q1 and Q2. The base of transistor Q1 receives the excitation of an external signal, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the base of transistor Q2, the emitter of transistor Q2 is connected to the positive terminal VCC of the power supply, and the emitter of transistor Q2 is connected to its base through resistor R2. The collector of transistor Q2 outputs a control signal.

3. The low-side driver with current limit and diagnostic function according to claim 1, wherein, The load circuit includes a load resistor RL1, the input terminal of which is connected to the positive terminal VCC of the power supply, and the output terminal of which is connected to the drain of the field-effect transistor Q5.

4. The low-side driver with current limit and diagnostic function according to claim 1, wherein, The sampling circuit includes a sampling resistor R11. One end of the sampling circuit R11 is connected to the source of the field-effect transistor Q5, and the other end of the sampling circuit R11 is grounded.

5. The low-side driver with current limit and diagnostic function according to claim 4, wherein, The amplification circuit includes an amplifier U1, the non-inverting input of which is connected to one end of the sampling circuit R11 to amplify the voltage signal sampled by the sampling resistor R11; the output of the amplifier U1 transmits the amplified voltage signal to the base of the first transistor in the protection circuit and the diagnostic output circuit, respectively, and the diagnostic output circuit outputs the amplified voltage signal to an external diagnostic device.

6. The low-side driver with current limit and diagnostic function according to claim 3, wherein, The protection circuit includes a transistor Q3, which serves as the first transistor. The collector of transistor Q3 is connected to the gate of field-effect transistor Q5, the emitter of transistor Q3 is grounded, and the base of transistor Q3 receives the voltage signal output by the amplifier circuit. When the voltage signal is greater than the turn-on voltage of transistor Q3, transistor Q3 turns on, grounding the gate of field-effect transistor Q5, thereby making the gate voltage of field-effect transistor Q5 zero, cutting off the loop of the load circuit, and allowing the load circuit to operate within the limited current range.

7. The low-side driver with current limit and diagnostic function according to claim 5, wherein, A diode D5 is provided between the base of the first transistor and the output terminal of the amplifier U1. The anode of the diode D5 is connected to the output terminal of the amplifier U1, and the cathode of the diode D5 is connected to the base of the first transistor to prevent short circuit caused by the backlash of the voltage signal output by the second transistor in the holding circuit.

8. The high-power low-side drive device with current limiting and diagnostic functions according to claim 5, characterized in that, The diagnostic output circuit includes a resistor R16 and a grounding capacitor C4. One end of the resistor R16 is connected to the output terminal of the amplifier U1 to receive the amplified voltage signal. The other end of the resistor R16 outputs the amplified voltage signal to an external diagnostic device. The other end of the resistor R16 is also connected to the grounding capacitor C4 to filter the output signal.

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