Stock Code:800328

Poor heat dissipation of the FET of the inverter or working in an on-off state can cause the tube to heat up


The field effect tube of the inverter works in the on-off state, and the current flowing through the tube is very large. If the tube selection is not appropriate, the driving voltage amplitude is not large enough, or the heat dissipation of the circuit is not good, the field effect tube may heat up.


1. Inappropriate selection of FETs


The FET in the inverter works in the on-off state. Generally, its drain current is required to be as large as possible, and the on-resistance is as small as possible, which can reduce the saturation voltage drop of the tube, thereby reducing tube consumption and reducing Small heat.


Looking at the FET manual, we will find that the higher the withstand voltage value of the FET, the greater its on-resistance, and those tubes with large drain current and low withstand voltage value, their on-resistance is generally in the number of digits. less than ten milliohms.


2. The driving voltage of the driving circuit is not large enough


The FET is a voltage control device. If you want to reduce the tube consumption and heat generation, the amplitude of the driving voltage of the FET gate should be large enough, and the edge of the driving pulse should be steep, which can reduce the power consumption of the tube. Pressure drop, reduce pipe consumption.


3. The heat dissipation of the FET is not good


Due to the large tube consumption of the FET of the inverter, an external heat sink with a large enough area is generally required during operation, and the external heat sink should be in close contact with the heat sink of the FET itself (generally, it is required to apply thermal conductive silicone grease) , If the external heat sink is small or the contact with the heat sink of the FET itself is not close enough, it can cause the tube to heat up.


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