Hello,
I am using IPT059N15N3 mosfet as load switch together with LT4363 IC. During board level and system level test, circuit works well. However, after weeks of operation circuit fails as explained below:
1) Mosfet cannot be turned on by the IC. When I measure gate source resistance, it seems 0 ohm(mosfet 1), 200 ohm (mosfet 2), 3kohm (mosfet 3) . Due to these low impedances LT4363 cannot drive the gate.
2) When I desolder mosfets and measure gate source resistances , it seems a few megaohm (mosfets 1& mosfet 2), resistance between pads of mosfets on PCB is also in megaohms range.
3) After resoldering mosfet1 and mosfet 2, gate source low impedance disappears and circuits starts to operate again.
4) The case is different for mosfet 3. Its damage seems permanent and circuit does not start operating unless I solder new mosfet.
When I check mosfet SOA, design seems OK. There is no dust or any material on PCB that can cause temporary short
What can be reason for this type of failure?
There is temporary damage on mosfet 1 & 2 while mosfet 3 was permanently damaged. How it is possible?
Thank you
