Low-side driving circuit with current-limiting output
By combining resistors and switching transistors in the current limiting protection module, the problem of damage to the low-side drive circuit under overcurrent is solved, achieving safety and reliability protection for the circuit.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- EAST JOY LONG AUTOMOBILE ELECTRONICS SHANGHAI
- Filing Date
- 2025-04-30
- Publication Date
- 2026-04-17
AI Technical Summary
Low-side drive circuits are prone to causing excessive transistor voltage during overcurrent conditions, which can damage the equipment.
A current-limiting protection module is adopted, including a second switching transistor and a resistor. The voltage drop of the resistor triggers the second switching transistor to turn on, which pulls down the base voltage of the first switching transistor and turns it off, thereby achieving overcurrent protection.
This effectively avoids damage to the first switching transistor caused by overcurrent, improving the safety and reliability of the circuit.
Smart Images
Figure CN224138985U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of drive circuits, and in particular to a low-side drive circuit with current-limiting output. Background Technology
[0002] Low-side drive circuits are widely used in various electronic devices, such as automotive electronics and industrial automation. The main function of this circuit is to provide a stable current supply when the load needs to operate and to promptly cut off the power supply in case of abnormal conditions to prevent damage to downstream equipment. With technological advancements, low-side drive circuits have played a crucial role in improving system reliability and safety, becoming an indispensable part of modern electronic devices.
[0003] The low-side drive circuit is mainly built with transistors. When an overcurrent occurs, the voltage flowing through the transistor will be too high, which can easily affect the performance of the transistor or even damage it. Utility Model Content
[0004] To achieve overcurrent protection for the low-side drive circuit, this application provides a low-side drive circuit with current-limiting output.
[0005] The low-side drive circuit with current-limited output provided in this application adopts the following technical solution:
[0006] A low-side drive circuit with current-limited output includes a control module, an output terminal P_SW, a first switch Q1, and a current-limiting protection module. The output terminal of the control module is electrically connected to the control terminal of the first switch Q1, the input terminal of the first switch Q1 is electrically connected to the output terminal P_SW, and the output terminal of the first switch Q1 is grounded through the current-limiting protection module. When the output terminal P_SW outputs an overcurrent signal, the current-limiting protection module can turn off the first switch Q1.
[0007] By adopting the above technical solution, during normal operation, the control module turns on the first switch Q1, and the current limiting protection module is not triggered at this time, allowing the output terminal P_SW to be grounded sequentially through the first switch Q1 and the current limiting protection module, enabling the circuit to operate normally. When the current output by the output terminal P_SW is too large, the current limiting protection module can turn off the first switch Q1, thereby shutting off the output of the output terminal P_SW and achieving overcurrent protection.
[0008] Preferably, the current limiting protection module includes a second switch Q2 and a resistor R3. The control terminal of the second switch Q2 is electrically connected to the output terminal of the first switch Q1, the output terminal of the second switch Q2 is grounded, and the input terminal of the second switch Q2 is electrically connected to the control terminal of the first switch Q1. One end of the resistor R3 is electrically connected to the output terminal of the first switch Q1, and the other end of the resistor R3 is grounded.
[0009] By adopting the above technical solution, when the current output at the output terminal P_SW increases, the voltage drop of resistor R3 also increases. If the voltage drop of resistor R3 exceeds the turn-on voltage of the second switch Q2, the second switch Q2 turns on, and the base of the first switch Q1 is pulled low, thereby turning off the first switch Q1 and shutting off the output at the output terminal P_SW.
[0010] Preferably, the second switching transistor Q2 is an NPN transistor.
[0011] By adopting the above technical solution, the selection of NPN transistors can ensure fast circuit response and reliable protection.
[0012] Preferably, the control module includes a control terminal VIN_CTL, a resistor R1, and a resistor R2. The control terminal VIN_CTL is grounded through the resistors R1 and R2 in sequence, and the connection point between the resistors R1 and R2 is connected to the control terminal of the first switching transistor Q1.
[0013] By adopting the above technical solution, resistors R1 and R2 form a voltage divider circuit, which can provide a suitable bias voltage to the base of the first switching transistor Q1, ensuring the stable conduction of the first switching transistor Q1 under normal operating conditions, while preventing excessive voltage from damaging the first switching transistor Q1.
[0014] Preferably, the control module further includes a capacitor C1, one end of which is electrically connected to the control terminal VIN_CTL, and the other end of which is grounded.
[0015] By adopting the above technical solution, capacitor C1 can effectively filter and improve the stability of the VIN_CTL output at the control terminal.
[0016] Preferably, the first switching transistor Q1 is an NPN transistor.
[0017] By adopting the above technical solution and using an NPN transistor as the first switching transistor Q1, the response speed and reliability of the circuit can be effectively improved. The NPN transistor has a low saturation voltage drop and can quickly switch states at high frequencies, thus ensuring efficient operation of the circuit in normal working mode. At the same time, the NPN transistor has a simple structure, is easy to integrate and maintain, and reduces manufacturing costs. Furthermore, the conduction characteristics of the NPN transistor allow it to quickly cut off during overcurrent protection, enhancing the safety and stability of the circuit.
[0018] Preferably, a capacitor C2 is also included, one end of which is electrically connected to the collector of the first switching transistor Q1, and the other end of which is grounded.
[0019] By adopting the above technical solution, high-frequency noise is effectively filtered out and the stability of the output current is improved, thereby ensuring the reliability and safety of the entire low-side drive circuit.
[0020] In summary, this application includes at least one of the following beneficial technical effects:
[0021] When the output current of the output terminal P_SW is too large, the second switch Q2 in the current limiting protection module can be turned on, thereby pulling down the base voltage of the first switch Q1 and turning off the first switch Q1, thus cutting off the output of the output terminal P_SW. This effectively avoids damage to the first switch Q1 caused by overcurrent and improves the safety and reliability of the circuit. Attached Figure Description
[0022] Figure 1 This is a circuit diagram of an embodiment of this application.
[0023] Reference numerals: 1. Control module; 2. Current limiting protection module. Detailed Implementation
[0024] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.
[0025] This application discloses a low-side drive circuit with current-limited output.
[0026] Reference Figure 1A low-side drive circuit with current-limited output includes a control module 1, an output terminal P_SW, a first switching transistor Q1, and a current-limiting protection module 2. The output terminal of the control module 1 is electrically connected to the control terminal of the first switching transistor Q1, the input terminal of the first switching transistor Q1 is electrically connected to the output terminal P_SW, and the output terminal of the first switching transistor Q1 is grounded through the current-limiting protection module 2. Under normal conditions, the first switching transistor Q1 is turned on, and the output terminal P_SW is grounded sequentially through the first switching transistor Q1 and the current-limiting protection module 2, achieving normal circuit function. When the output terminal P_SW outputs an overvoltage signal, the current-limiting protection module 2 can turn off the first switching transistor Q1, thereby shutting off the output of the output terminal P_SW and achieving overcurrent protection.
[0027] Control module 1 includes a control terminal VIN_CTL, resistors R1 and R2, and in this embodiment, the first switching transistor Q1 is set as an NPN transistor. The control terminal VIN_CTL is grounded through resistors R1 and R2 in sequence, and the connection point between resistors R1 and R2 is connected to the base of the first switching transistor Q1. Resistors R1 and R2 act as a voltage divider, thereby ensuring that the base of the first switching transistor Q1 receives a suitable voltage, thus protecting the first switching transistor Q1.
[0028] Preferably, the control module 1 further includes a capacitor C1, one end of which is electrically connected to the control terminal VIN_CTL, and the other end of which is grounded. The capacitor C1 serves as a filter and voltage regulator, thereby ensuring the stability of the output of the control terminal VIN_CTL.
[0029] The current limiting protection module 2 includes a second switching transistor Q2 and a resistor R3. In this embodiment, the second switching transistor Q2 is an NPN transistor. The base of the second switching transistor Q2 is electrically connected to the emitter of the first switching transistor Q1, and the emitter of the second switching transistor Q2 is grounded. The collector of the second switching transistor Q2 is electrically connected to the base of the first switching transistor Q1, and the collector of the first switching transistor Q1 is electrically connected to the output terminal P_SW. One end of the resistor R3 is electrically connected to the emitter of the first switching transistor Q1, and the other end of the resistor R3 is grounded.
[0030] Under normal circumstances, the high-level output of the control terminal VIN_CTL turns on the first switch Q1, allowing the output terminal P_SW to be grounded sequentially through the first switch Q1 and resistor R3. When the output current of P_SW increases, the voltage drop across resistor R3 also increases. If the voltage drop across resistor R3 exceeds the turn-on voltage of the second switch Q2, Q2 turns on, pulling down the base voltage of the first switch Q1 and turning it off, thus shutting off the output of P_SW and providing protection. The current limit can be configured according to actual needs by adjusting the Vbe junction voltage of the second switch and the resistance value of resistor R3.
[0031] Preferably, this embodiment further includes a capacitor C2, one end of which is electrically connected to the collector of the first switching transistor Q1, and the other end of which is grounded. The capacitor C2 serves as a filter and voltage regulator, thereby making the output of the output terminal P_SW more stable.
[0032] The implementation principle of a low-side drive circuit with current-limiting output in this application embodiment is as follows: by setting the current-limiting protection module 2, it can promptly respond to abnormal situations when the output terminal P_SW outputs an overcurrent signal; when the current output by the output terminal P_SW is sufficient to trigger the second switch Q2 to conduct due to the voltage drop of the resistor R3, the first switch Q1 will be turned off, thereby playing the role of overcurrent protection and limiting the current value output by the output terminal P_SW.
[0033] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A low-side driver circuit with current limited output, characterized by: The device includes a control module (1), an output terminal P_SW, a first switching transistor Q1, and a current limiting protection module (2). The output terminal of the control module (1) is electrically connected to the control terminal of the first switching transistor Q1, and the input terminal of the first switching transistor Q1 is electrically connected to the output terminal P_SW. The output terminal of the first switching transistor Q1 is grounded through the current limiting protection module (2). When the output terminal P_SW outputs an overcurrent signal, the current limiting protection module (2) can turn off the first switching transistor Q1.
2. The low-side drive circuit with current-limited output according to claim 1, characterized in that: The current limiting protection module (2) includes a second switch Q2 and a resistor R3. The control terminal of the second switch Q2 is electrically connected to the output terminal of the first switch Q1. The output terminal of the second switch Q2 is grounded, and the input terminal of the second switch Q2 is electrically connected to the control terminal of the first switch Q1. One end of the resistor R3 is electrically connected to the output terminal of the first switch Q1, and the other end of the resistor R3 is grounded.
3. The low-side driver circuit with current limited output of claim 2, wherein: The second switching transistor Q2 is set as an NPN transistor.
4. The low-side driver circuit with current limited output of claim 1, wherein: The control module (1) includes a control terminal VIN_CTL, a resistor R1 and a resistor R2. The control terminal VIN_CTL is grounded through the resistor R1 and the resistor R2 in sequence, and the connection point between the resistor R1 and the resistor R2 is connected to the control terminal of the first switch Q1.
5. A low-side driver circuit with current limited output as claimed in claim 4, characterized in that: The control module (1) also includes a capacitor C1, one end of which is electrically connected to the control terminal VIN_CTL, and the other end of which is grounded.
6. The low-side driver circuit with current limited output of claim 1, wherein: The first switching transistor Q1 is set as an NPN transistor.
7. The low-side driver circuit with current limited output of claim 1, wherein: It also includes capacitor C2, one end of which is electrically connected to the collector of the first switching transistor Q1, and the other end of which is grounded.