Cause of serious heating of field effect tube
1, the problem of circuit design is to let the MOS tube work in a linear working state, rather than in a switching state. This is also a cause of MOS tube heating. If the N-MOS is a switch, the G-level voltage must be several V higher than the power supply to be switched on, and the P-MOS is the opposite. There is no open and the voltage drop is too large to cause power consumption, the equivalent DC impedance is large, the voltage drop increases, so U*I also increases, and the loss means heat. This is a taboo mistake in designing circuits;
2, the frequency is too high, mainly because sometimes excessive pursuit of volume, resulting in increased frequency, MOS tube loss increased, so the heat is also increased;
3, do not do enough heat dissipation design, the current is too high, the nominal current value of the MOS tube, generally need good heat dissipation to achieve. Therefore, if the ID is less than the larger current, the heat may also be serious, and sufficient auxiliary heat sink is required;
4, the selection of MOS tube is wrong, the power judgment is wrong, the internal resistance of MOS tube is not fully considered, resulting in increased switching impedance.