Hello,
I'm having some troubles with the TPS65185 starting up. I'm using a typical startup sequence: Wakeup pin high, Program part via I2C, then set powerup pin high and write the enable register.
Upon doing this, occasionally the part starts right up and works at the proper voltage, but most of the time it's stuck with the VN undervolt flag (register 0x08 = 0x20). I can see the VN trying to switch for some 150ms, but the output languishes around -5V before giving up. Interestingly, it seems to work more consistently if the input supply voltage to the part is lower, especially below ~3.45V. Also, regardless of the input supply voltage the part never fully starts up if a load (E ink display) is connected. Eventually the board will be powered by battery but for now it's being powered by a bench supply. My issue looks very similar to another one posted on this forum, except theire was found to be an issue with setting the powerup pin. I'm certain I'm doing this correctly.
Any ideas? Schematic is attached, although I've checked and double checked it against the EVM.
Thanks!