I am using 4 of the TPS54620 in my design to generate:
0.9V (higher current)
3.3V (higher current)
5.0V
1.2V
...and all are using the same 12V input rail
Doing only some simple scoping on it(simple analog scope only), here are some observations...
1. When the output drops(resets my FPGA cause 0.9V) then the 12V drops too so thought is that
the input is shorting bringing its output down(ideally I scope to determine which happens first).
2. All supplies look great until the shut down(very little ripple) with everything cranking
3. It seems to depend on the "mood" of the devices as to whether there is a shutdown
ie. sometimes I run for a while without interruption but other times it does not take long at all
and sometimes after a shut down it can also be good for a while without interruption after rebooting
(ie. good until I intentionally power it down many minutes later).
4. Nothing is hot at the point of shutdown.
5. The 12V is being powered by a 3A, 12V Circuit Test bench supply and the current out of this
is about 0.7A with everything cooking.
6. Boards are all machine built by a professional CM so expect no build issues - just design issues.
Thoughts?
