Tom Bruhns a écrit :


With a switching regulator,
things probably wouldn't be nearly as bad, but the dissipation may
still go up in the switching parts if you short the output.


One pb with SMPS is that when you crowbar its output the input current
is lowered since you ask for lower output power. You'll never blow the fuse.
Another point, depending on the SMPS structure and on the controller
minimum on time is that you have pretty low output voltage when
crowbared (?) which may be too low to reset the inductor current (for
ex. flyback, buck).
In some poorly design supplies this might lead to higher and higher
switch/diode currents, inductor saturation, sill higher currents and
then fireworks.
I prefer latching the fault condition then inhibit the controller, with
crowbar or not, which is what you recommend below.
The other thing I've seen is a crowbar for fast response, and a
latching shutdown fed back to the supply that holds it off until
something is reset.


--
Thanks,
Fred.