MOS tube, fully called Metal Oxide Semiconductor Field Effect Transistor, is a kind of field effect tube, named after the three-layer structure of metal, oxide and semiconductor. There are two types of MOS tubes: n-channel MOS tubes (NMOS) and p-channel MOS tubes (PMOS). According to these two types, MOS tubes can be further divided into enhanced and depleted types.
The main characteristics of MOS transistor are high input impedance, low power consumption, small size, high operating frequency and strong radiation resistance, so it is widely used in integrated circuit design. Especially in digital logic circuits, analog circuits, memory circuits and power electronic circuits, MOS transistors have important applications.
However, when using MOS transistor in design, it should be noted that due to its working principle, it is more than BQ24031RHLR The triode is more vulnerable to damage from static electricity and overvoltage. The gate of MOS tube is isolated from the source and drain through an insulated silicon oxide layer. This insulation layer is extremely thin, so it can be easily broken down by high voltage. In practical applications, MOS transistors are easy to burn out in the design of switching circuits without proper protective measures.
The main reasons why triode is easy to burn out in the design of MOS switch circuit are as follows:
1. Insufficient current driving capacity: the current driving capacity of the triode is weak. When it is connected to the output end of the MOS transistor, it may not be able to provide enough current to drive the load, causing the triode to overload and burn out.
2. Transient over-voltage/over-current: During the switching process of MOS transistors, the triode cannot withstand these over-voltage or over-current and is vulnerable to damage due to the possible transient fluctuations of the voltage and current at the output end.
3. Insufficient reverse breakdown protection: In the MOS switch circuit, the output end often needs reverse breakdown protection to avoid damage, while the reverse breakdown capacity of the triode may be insufficient, resulting in damage.
In order to solve the problem that triode is easy to burn out in the design of MOS switch circuit, the following measures can be taken:
1. Increase the current limiting resistance: set appropriate current limiting resistance on the base of the triode to limit the output current and avoid overload damage.
2. Add protection circuit: the over-voltage and over-current protection circuit can be designed at the output terminal. When the output terminal is abnormal, the overload can be removed in time to protect the triode from damage.
3. Select a suitable triode model: select a triode model with high current drive capability and reverse breakdown capability to ensure stable and reliable operation in the design of MOS switch circuit.
When designing MOS switch circuit, reasonable consideration of triode selection and protection measures can effectively reduce the risk of triode burnout and improve the reliability and stability of the entire circuit.
In order to prevent these problems, we usually take some protective measures when designing the MOS switch circuit, such as adding an overcurrent protection circuit, using an appropriate heat dissipation design, or adding a reverse diode between the gate and the source of the MOS tube to prevent the damage of static electricity and overvoltage to the MOS tube. 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.
