Switching circuit capable of driving large current
By combining parallel PMOS transistor design and protection modules, the problem of microcontrollers being unable to drive large currents was solved, enabling stable driving of high-power loads and improving circuit safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUIZHOU GAOSHENGDA OPTOELECTRONIC TECH CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-06-05
AI Technical Summary
When a microcontroller uses a single PMOS transistor to connect to a 12V load, the current capacity is insufficient to drive a high-power load, resulting in high-voltage backflow that damages the microcontroller.
The switching circuit design employs two PMOS transistors connected in parallel, combined with a current limiting unit, pull-up resistors, protection modules, and control modules, including thermistors, fuses, TVS diodes, and capacitors, to improve load current capacity and provide protection.
It effectively improves the load current capacity, can stably drive high-power equipment, avoids single tube overload burnout, and ensures control signal transmission and circuit safety.
Smart Images
Figure CN122159844A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of circuit design technology, and in particular to a switching circuit capable of driving large currents. Background Technology
[0002] In related technologies, some microcontrollers use a single PMOS transistor to connect to a 12V load. However, because the current capacity supported by a single PMOS transistor is low, it cannot drive a high-power 12V load, which leads to high voltage backflow and damages the microcontroller. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a switching circuit that can drive high current, thereby increasing the load current capacity and driving high-power loads.
[0004] The objective of this invention is achieved through the following technical solution: The first aspect of this application provides a switching circuit capable of driving high current, comprising: an input module including a current limiting unit and a pull-up resistor R16, wherein the current limiting unit is electrically connected to a first terminal of the pull-up resistor R16; a control module including a PMOS transistor Q9 and a PMOS transistor Q8, wherein the PMOS transistor Q9 is electrically connected to a first terminal and a second terminal of the pull-up resistor R16 respectively, and the PMOS transistor Q8 is electrically connected to the PMOS transistor Q9; and a protection module electrically connected to the PMOS transistor Q9 and the PMOS transistor Q8 respectively.
[0005] The current limiting unit includes resistor R17 and resistor R18. The first end of resistor R17 is electrically connected to the first end of resistor R18, and the second end of resistor R18 is electrically connected to the first end of pull-up resistor R16.
[0006] The current limiting unit also includes a pin PA1, which is electrically connected to the second end of the resistor R17.
[0007] The resistance of resistor R17 is 10 kilohms.
[0008] The resistance of the resistor R18 is 4.7 kΩ.
[0009] The protection module includes a thermistor R20, the first end of which is electrically connected to the PMOS transistor Q9.
[0010] The protection module also includes a diode D6, the first end of which is electrically connected to the second end of the thermistor R20, and the second end of which is electrically connected to the PMOS transistor Q9 and the PMOS transistor Q8 respectively.
[0011] The protection module also includes a fuse F2, which is electrically connected to the PMOS transistor Q9 and the PMOS transistor Q8 respectively.
[0012] The protection module also includes a TVS diode D7, the first end of which is electrically connected to the first end of the diode D6, and the second end of the TVS diode D7 is grounded.
[0013] The protection module also includes capacitors C15 and C16. The first end of capacitor C15 is electrically connected to the first end of TVS diode D7, and the second end of capacitor C15 is grounded. The first end of capacitor C16 is electrically connected to the first end of capacitor C15, and the second end of capacitor C16 is grounded.
[0014] Compared with the prior art, the present invention has at least the following advantages: This application can significantly increase the load current capacity by connecting two PMOS transistors in parallel, and can also stably drive higher power devices, effectively avoiding single transistor burnout due to insufficient load capacity of a single MOS transistor. Attached Figure Description
[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.
[0016] Figure 1 This is a functional block diagram of a high-current-driving switching circuit according to an embodiment of the present invention. Figure 2 This is a circuit diagram of a high-current-driving switching circuit according to an embodiment of the present invention. Detailed Implementation
[0017] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.
[0018] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0019] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0020] Currently, some microcontrollers use a single PMOS transistor to connect to a 12V load. However, because a single PMOS transistor has a low current capacity, it cannot drive a high-power 12V load, which leads to high voltage backflow and damages the microcontroller.
[0021] To address the aforementioned issues, embodiments of this application provide a switching circuit capable of driving high current, which can increase the load current capacity and thus drive high-power loads.
[0022] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.
[0023] See Figure 1 and Figure 2 A high-current switching circuit includes: an input module, a control module, and a protection module. The input module includes a current-limiting unit and a pull-up resistor R16, with the current-limiting unit electrically connected to the first terminal of the pull-up resistor R16. The control module includes a PMOS transistor Q9 and a PMOS transistor Q8, with PMOS transistor Q9 electrically connected to the first and second terminals of the pull-up resistor R16, and PMOS transistor Q8 electrically connected to PMOS transistor Q9. The protection module is electrically connected to both PMOS transistors Q9 and Q8.
[0024] It should be noted that the current limiting unit is used to limit the current within a safe range. The pull-up resistor R16 ensures that the gates of both MOSFETs are pulled to +12V when there is no control signal, and both MOSFETs are off by default, thus solving the problem of accidental power-on of the device from a hardware perspective. Furthermore, the parallel connection of PMOS transistors Q9 and Q8 can increase the load current capacity to over 12A, stably driving higher-power 12V devices. It also effectively prevents single-MOSFET burnout due to insufficient load capacity. Through the isolation effect of the PMOS transistors, the circuit effectively achieves 3.3V low-voltage control of 12V high-voltage, ensuring effective transmission of the control signal and isolating the 12V high-voltage from impacting the STM32, improving circuit safety. In addition, the source (S) is connected to a common +12V high potential, and the gate (G) is connected to the same control node, communicating with the control circuit of the microcontroller's PA1; the drain (D) is connected to the positive terminal of the output load, and the load current is evenly distributed between the two transistors. When the microcontroller's I / O port outputs a low level, the gate is pulled low, both transistors are turned on, and +12V is output to the device through the drain. When the microcontroller's I / O port outputs a high level, the gate is pulled up to 12V by the pull-up resistor R16, both transistors are turned off, and the device is powered off.
[0025] See Figure 2 In one embodiment, the current limiting unit includes resistors R17 and R18. The first end of resistor R17 is electrically connected to the first end of resistor R18, and the second end of resistor R18 is electrically connected to the first end of pull-up resistor R16. Specifically, the current limiting unit also includes pin PA1, which is electrically connected to the second end of resistor R17.
[0026] Preferably, the resistance of resistor R17 is 10 kilohms.
[0027] Preferably, the resistance of resistor R18 is 4.7 kΩ.
[0028] It should be noted that the total resistance of resistors R17 and R18 is 14.7KΩ, which can limit the output current of the IO port to a safe range of about 0.22mA, effectively protecting the PA1 pin of the microcontroller.
[0029] See Figure 2 In one embodiment, the protection module includes a thermistor R20, the first end of which is electrically connected to the PMOS transistor Q9.
[0030] It should be noted that the thermistor R20 is connected in series between the +12V input and the source and source of the MOSFET. At the moment of power-on, the thermistor R20 has a relatively high resistance at room temperature, which can limit the inrush current when the load or motor starts. After the circuit is operating stably, the resistance of the thermistor R20 drops to about 1Ω, but this does not affect the current transmission.
[0031] See Figure 2In one embodiment, the protection module further includes a diode D6, the first end of which is electrically connected to the second end of the thermistor R20, and the second end of which is electrically connected to PMOS transistors Q9 and Q8 respectively.
[0032] It should be noted that the anode of the freewheeling diode D6 is connected to the drain of both MOSFETs, and the cathode is connected to +12V. When the MOSFETs are turned off, the windings of the motor load will generate a reverse electromotive force. The freewheeling diode D6 provides a discharge path for this electromotive force, preventing high voltage from breaking down the MOSFETs and preventing it from causing electromagnetic interference to the frequency converter circuit.
[0033] See Figure 2 In one embodiment, the protection module further includes a fuse F2, which is electrically connected to PMOS transistors Q9 and Q8 respectively.
[0034] It should be noted that fuse F2 is connected in series between the drain (D) of the MOSFET and the main current path of the load P4. When the load is short-circuited or the current exceeds 15A, fuse F2 will heat up rapidly, its resistance will increase sharply, and it will cut off the +12V power supply to the load. After the fault is cleared, fuse F2 will automatically cool down and resume conduction, and does not need to be replaced.
[0035] See Figure 2 In one embodiment, the protection module further includes a TVS diode D7, the first end of which is electrically connected to the first end of a diode D6, and the second end of the TVS diode D7 is grounded.
[0036] It should be noted that the TVS diode D7 can be an SMBJ15CA. It is connected in parallel with the +12V input and GND near the power supply inlet. When a surge voltage occurs on the 12V power supply line, the TVS diode turns on, and the surge is discharged to GND to prevent high voltage from damaging the MOSFET.
[0037] See Figure 2 In one embodiment, the protection module further includes capacitors C15 and C16. The first end of capacitor C15 is electrically connected to the first end of TVS diode D7, and the second end of capacitor C15 is grounded. The first end of capacitor C16 is electrically connected to the first end of capacitor C15, and the second end of capacitor C16 is grounded.
[0038] It should be noted that capacitors C15 and C16 can filter out high-frequency interference signals from the PMOS transistor gate, improve the stability of the MOS transistor's switching operation, and prevent abnormal load switching.
[0039] The solution of this application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have different focuses; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. Those skilled in the art should also understand that the actions and modules involved in the specification are not necessarily essential to this application. Furthermore, it is understood that the steps in the method of this application embodiment can be adjusted, combined, and deleted according to actual needs, and the modules in the device of this application embodiment can be combined, divided, and deleted according to actual needs. The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A switching circuit capable of driving high current, characterized in that, include: The input module includes a current limiting unit and a pull-up resistor R16, wherein the current limiting unit is electrically connected to the first end of the pull-up resistor R16; The control module includes PMOS transistors Q9 and Q8. PMOS transistor Q9 is electrically connected to the first and second terminals of the pull-up resistor R16, respectively, and PMOS transistor Q8 is electrically connected to PMOS transistor Q9. The protection module is electrically connected to PMOS transistors Q9 and Q8 respectively.
2. The switching circuit capable of driving high current according to claim 1, characterized in that, The current limiting unit includes resistor R17 and resistor R18. The first end of resistor R17 is electrically connected to the first end of resistor R18, and the second end of resistor R18 is electrically connected to the first end of pull-up resistor R16.
3. The switching circuit capable of driving high current according to claim 2, characterized in that, The current limiting unit also includes a pin PA1, which is electrically connected to the second end of the resistor R17.
4. The switching circuit capable of driving high current according to claim 2, characterized in that, The resistance of resistor R17 is 10 kilohms.
5. The switching circuit capable of driving high current according to claim 2, characterized in that, The resistance of the resistor R18 is 4.7 kΩ.
6. The switching circuit capable of driving high current according to claim 1, characterized in that, The protection module includes a thermistor R20, the first end of which is electrically connected to the PMOS transistor Q9.
7. The switching circuit capable of driving high current according to claim 6, characterized in that, The protection module also includes a diode D6, the first end of which is electrically connected to the second end of the thermistor R20, and the second end of which is electrically connected to the PMOS transistor Q9 and the PMOS transistor Q8 respectively.
8. The switching circuit capable of driving high current according to claim 1, characterized in that, The protection module also includes a fuse F2, which is electrically connected to the PMOS transistor Q9 and the PMOS transistor Q8 respectively.
9. The switching circuit capable of driving high current according to claim 7, characterized in that, The protection module also includes a TVS diode D7, the first end of which is electrically connected to the first end of the diode D6, and the second end of the TVS diode D7 is grounded.
10. The switching circuit capable of driving high current according to claim 9, characterized in that, The protection module also includes capacitors C15 and C16. The first end of capacitor C15 is electrically connected to the first end of TVS diode D7, and the second end of capacitor C15 is grounded. The first end of capacitor C16 is electrically connected to the first end of capacitor C15, and the second end of capacitor C16 is grounded.