Why is it easy to burn out transistors in MOS switch circuit design? How to solve it?

MOS transistor, also known as Metal Oxide Semiconductor Field Effect Transistor, is a type of field-effect transistor named after a three-layer structure consisting of metal, oxide, and semiconductor. There are two types of MOSFETs: N-channel MOSFETs (NMOS) and P-channel MOSFETs (PMOS). Based on these two types, MOSFETs can be further divided into enhancement and depletion types.

The main characteristics of MOS transistors are high input impedance, low power consumption, small size, high operating frequency, and strong radiation resistance, so they are widely used in integrated circuit design. Especially in the fields of digital logic circuits, analog circuits, storage circuits, and power electronic circuits, MOS transistors have important applications.

However, when designing and using MOS transistors, it should be noted that due to their working principle, they are more susceptible to static electricity and overvoltage damage than BQ24031RHLR transistors. The gate of a MOS transistor is isolated from the source and drain by an insulating silicon oxide layer. This insulation layer is extremely thin, so it can be easily broken down by high voltage. In practical applications, without appropriate protective measures, MOS transistors are prone to burnout in switch circuit design.

The main reasons why transistors are prone to burnout in MOS switch circuit design are as follows:

1. Insufficient current driving capability: The current driving capability of the transistor is weak. When connected to the output terminal of the MOS transistor, it may not be able to provide sufficient current to drive the load, resulting in overload and burnout of the transistor.

2. Transient overvoltage/overcurrent: During the switching process of MOS transistors, transient fluctuations in the output voltage and current may occur, and the transistor cannot withstand these overvoltage or overcurrent and is easily damaged.

3. Insufficient reverse breakdown protection: In MOS switch circuits, it is often necessary to perform reverse breakdown protection on the output terminal to avoid damage, and the reverse breakdown capability of the transistor may be insufficient, leading to damage.

To solve the problem of transistor burnout in MOS switch circuit design, the following measures can be taken:

1. Increase current limiting resistor: By setting an appropriate current limiting resistor at the base of the transistor, the magnitude of the output current can be limited to avoid overload damage.

2. Add protection circuit: Overvoltage and overcurrent protection circuits can be designed at the output terminal to promptly eliminate overload and protect the transistor from damage when an abnormality occurs at the output terminal.

3. Choose the appropriate transistor model: Choose a transistor model with high current driving capability and reverse breakdown capability to ensure stable and reliable operation in MOS switch circuit design.

When designing MOS transistor switch circuits, reasonable consideration of transistor selection and protection measures can effectively reduce the risk of transistor burnout and improve the reliability and stability of the entire circuit.

To prevent these issues, we usually adopt some protective measures when designing MOS transistor switch circuits, such as adding overcurrent protection circuits, using appropriate heat dissipation designs, or adding a reverse diode between the gate and source of the MOS transistor to prevent static electricity and overvoltage damage to the MOS transistor. In addition, we can also choose to use some transistors that are more resistant to overheating and overcurrent to improve the reliability of the circuit