The cause of heating in field-effect transistors

1. Issues in Circuit Design

It is to make the MOS transistor work in a linear working state, rather than in a switching circuit state. This is also one of the reasons for the heating of MOS transistors. If N-MOS is used as a switch, the G-level voltage needs to be several volts higher than the power supply in order to fully conduct, while P-MOS is the opposite. The failure to fully open and excessive voltage drop result in high power consumption, high equivalent DC impedance, and increased voltage drop. Therefore, U * I also increases, and the loss means heat generation. This is the most taboo mistake in designing circuits.

2. The frequency is too high

Mainly due to the excessive pursuit of volume, the frequency increases and the losses on the MOS transistor increase, resulting in increased heat generation.

3. Insufficient heat dissipation design

The current is too high, and the nominal current value of the MOS transistor generally requires good heat dissipation to achieve. So if the ID is less than the maximum current, it may also cause severe heating and require sufficient auxiliary heat sinks.

4. Incorrect selection of MOS transistor

The power judgment was incorrect, and the internal resistance of the MOS transistor was not fully considered, resulting in an increase in switch impedance.