Hi TI Engineers,
I use EPC power switch to make a quarter brick module power supply(36-72V input，12V output).The main circuit topology is full bridge hard switching circuit.With UCC28251 analog controller, the driving logic is correct.The problem is that the synchronous tube breaks down as soon as it is powered on at 36V input.Previously, the power transistors of the original side of the bridge arm were also broken down because they were not welded well. But the second time, six power transistors were welded simultaneously with a small reflow welding machine, and the four power transistors of the original side of the bridge arm were welded well by detecting the midpoint voltage of the bridge arm.All six power transistors are EPC2022 rated withstand voltage 100V.In addition to the welding problem, I want to know if there are any other reasons for the breakdown of the synchronous rectifier tube.
Another question is how do I test that the synchronous rectifier switch is welded properly?
best regars,
shao wei
