Supply sequencing requirements

The various supplies and BUCKEN need to be sequenced in order with delay requirements.

The power-up sequence and requirements are:

1. Supply VBAT/BUCKVBAT/BUCKVBATS/AFEVBAT
2. Wait ≥ 6 ms
3. Assert BUCKEN
4. Wait ≥ 1 ms
5. Supply IOVDD

PWRIOVDD is an internally generated supply, used for supplying OTPVDD through an external connection. It cannot be used for anything else. This supply is automatically controlled in the device.

The power-down sequence and requirements are:

1. Drive all host-side IOs to GND (for example QSPI data lines, or COEX requests)
2. Wait ≥ 0 ms
3. Power down IOVDD
4. Wait ≥ 0 ms
5. De-assert BUCKEN
6. Wait ≥ 0 ms
7. Power down VBAT

The steps do not require specific timing delays, but they must occur in the correct sequence.