TPS7A39: inconsistent

Hi Dylan,

I'm trying to evaluate your schematic and layout but the designators are pixelated and hard to make out. Also from what I can tell, the designators on the layout do not match up with the designators on the schematic. Can you post higher-resolution pictures and verify that the layout is indeed showing the correct IC?

Thanks,

Nick

hopefully this is a little clearer, FL1, and FL2 are NFE61PT472C1H9L they are the only thing between the LDOs and the output connector on the board

Hi Dylan,

I don't see anything wrong with the implementation. You said it works about 30% of the time as expected; are you saying that about 30% of boards work correctly or are you replacing the LDO and re-testing with a fresh device on the same board? 

Have you attempted to capture scope shots of the startup? It seems unlikely, but I wonder if the +/- 24V supplies are overshooting or something like that and causing an overvoltage condition on startup.

Regards,

Nick

assembled boards I've attempted reworking the sane board by replacing the ldo utilizing a mini paste stencil and solder utilizing a reflow oven, but none of the reworked boards ever work, it seems to either work or nor. the +- 24v supply is the same across all testing. Thank for taking the time to look it over