Maybe the use case as well. The guys making spot welders always recommend
using FETs instead of SCRs due to FETs always failing open vs the SCRs
always failing closed.
So massive high current pulses vs contant duty cycle.
-Dan
On Wed, 28 Sep 2016, NeonJohn wrote:
I can't speak for low power FETs. The smallest thing I deal with is a
100 watt fan speed controller. I have a box under my lab bench that I
call my "L'il box of larnin' " that contains all the FETs and IGBTs that
have failed during development over the past 10 years or so. A thousand
at least. There's not a single device in that box that failed open.
John
On 09/28/2016 02:38 PM, Dan Hollis wrote:
I thought FETs always fail open, and it was SCRs which always fail shorted.
-Dan
On Wed, 28 Sep 2016, NeonJohn wrote:
On 09/28/2016 12:40 PM, Trumpeter wrote:
Thank you for this detailed explaination, even though some is over my
head.
Should I check the resistance between the two joined pins and one of
the two pins on the other side? Could the over heating mosfet damage
other components or will it simply fail?
The problem is that power FETS *ALWAYS* fail shorted. So you need to
plan your circuit and any protection for that eventuality. I'd put a
PolyFuse in the circuit supplying the circuit. That'll protect your
transformer and power source when the FET lets its smoke out.
John
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