Company new

Ideas to solve the serious heating of MOS diode

I don't know if you have found a problem, MOS as a switching power supply equipment sometimes serious heat during operation, want to solve the MOS heating problem, first we have to determine what causes it is, so we need to test, to find out where the problem is. By discovering the heat problem of MOS, to choos MOS e the correct key point test, whether it is consistent with the analysis, this is the key to solving the problem.

In the power supply test, in addition to measuring the pin voltage of other devices in the control circuit, the second is to use an oscilloscope to measure the relevant voltage waveform. When we go to judge whether the switching power supply is working normally, we can measure where to reflect whether the working state of the power supply is normal, whether the output end of the PWM controller is normal, whether the pulse duty cycle and amplitude are normal, whether the MOS of the switch is working normally, including the secondary and primary side of the transformer and whether the feedback of the output is reasonable.

It is very important that the test points are selected reasonably, and the correct choice can not only measure safely and reliably, but also allow us to quickly troubleshoot the cause.

Generally, the causes of MOS heating are:

1: The G pole driving voltage is not enough.

2: The Id current through the drain and source is too high.

3: The driving frequency is too high.

So the focus of the test is on the MOS , accurately testing out how it works, which is the root of the problem.

It should be noted that when we need to use an oscilloscope for testing, we should pay special attention to the fact that when gradually increasing the input voltage, if the peak voltage or current is found to be beyond our design range, at this time we must pay attention to the heating of the MOS , if there is an abnormality, we should immediately turn off the power to troubleshoot the problem and prevent the MOS from being damaged.