why fixed frequency current mode buck dc to dc converter damage chips which use it

[edisonliu]

I am debugging the issue as the tittle. The dc to dc output high votage sometimes. But we can not catch it. We guess there is some high voltage because the class d amplifier use its output as power is damaged. The amplifier power pad is damaged. Could somebody give us sone clue about it? Thanks very much.

 

[dick_freebird]

You would have to induce the (intermittent) problem and
capture it to understand.

You might look at load-dump (or loud-to-quiet) transitions
to see if there is an unacceptable overshoot on that load
step. See if the converter can be driven into current-limit
at max Class D load, perhaps winding up the control loop
and resulting in cross, non-small-signal overshoot when it
releases.

Power-up can also induce overshoots especially if soft
start ramp is faster than loop bandwidth limited control-
loop slew.