I am using various Simple switcher parts:
2x LMZ22008 (master/slave) +1V0
1x LMZ22005 +1V5
1x LMZ22003 +1V8
1x LMZ22003 +2V5
1x LMZ22008 +3V3
1x TPS62130 +3V6
There is audible noise coming from what appears to be the LMZ22008 used on the +3V3 supply.
Each supply has a ferrite bead and filter capacitors on the +12V input side.
The layout, schematic and input/output capacitors are in accordance with the datasheet.
Before i start isolating each supply and running load tests are there any pointers on what could
cause this type of instability.
I can provide layout and schematic information.