I am currently debugging a DM368 design and am seeing something weird with the power input.
I have sequenced power turning on as specified by the users guide with the sequence 1.35V, 1.8V and then 3.3V. While brining up the board, I noticed that 3.3 seemed to be coming up early. I pulled a power filter out of the system that was between my power switch FET and the DM368 I/O supply pins. With the power filter removed, my switch sequenced correctly, so I know that is working, but I noticed I was getting 3.3V on the supply pins that are now left floating. It is not clear to me what is sourcing the voltage as there is nothing on this net but disconnected power pins.
I surmise that this 3.3V is leakage from a pull up input elsewhere in the design. (Pullups to things like the FLASH module are powered before the DM368 I/O supplies). Is this a known behavior ? Also, is this a harmful behavior ? Could this cause reset issues due to 3.3V being present out of sequencing order ? What is the accepted design practice here ? Is it strictly forbidden to drive input I/Os before the DM368 IO supply is active ?