Is there any power supply sequencing required for SSM2603? Can this device withstand and function properly when these supplies are applied in any unspecified order ? Is there a requirement for HPVDD being identical to AVDD ? Or a requirement for AVDD being larger than DCVDD ? Is there any required relationship in-between these pins ? What exactly is supplied with DBVDD ? What needs to be supplied to make sure this device doesn't block the I2C bus ? Are there any clamp diodes in between these supply pins ? Are there clamp diodes from the SDA/SCL (I2C) pins to some supply which might block I2C traffic when this supply isn't applied yet ? Would the following scenario work properly ? DCVDD supplied with 1.8V (and shared with many other "digital" supply pins on a PCB) DBVDD supplied with 3.3V (and shared with many other "digital" supply pins on a PCB), DCVDD and DBVDD applied in non specified order?.
I2C needs to work even when AVDD and HPVDD isn't supplied yet.