We're using the TPS6590376 on an AM5728 Evaluation board. The board is installed on a baseboard I designed. We have found over the last few weeks that in order to boot the processor successfully using the Power On switch (which is tied directly to the PMIC POWERON pin), we have to apply power to the Eval board and our baseboard at separate times. Everyone has their own rituals that all seem to work - sometimes.
If I remove the Eval bd from the baseboard, it boots every time, as you'd expect.
When the Eval board is installed on the baseboard, and power is applied to them simultaneously, pressing the Power On switch has no effect - the processor doesn't start. However, if I press and hold the switch closed before applying power, and hold it until the power rails are up, the processor boots every time.
I suspect some sort of back-biasing from the baseboard's 3.0V PS, maybe through pullups on the Eval board. If I apply power to the baseboard only, the POWERON pin floats up to ~0.5V. I also route the processor's RESETOUTn pin to a gate on the baseboard.
Is it possible that some sort of latch-up is occurring in the TPS6590376?
Thanks!
MADman