Hi,
I do not think the device will be damaged from analog input and clock while power down. We sometimes leave the device in this situation but there has been no problem. I'll check this with test team.
ADS5463 has internal power-up time, 200us, from power supply and 3.5 clock cycles of data latency. ADS5463 requires a sequence of power-up as below and also you can refer to the page 37 of datasheet for more information.
- Power up both AVDD3 and DVDD3 at the same time (best scenario), or
- Keep the voltage difference less than 0.8V between AVDD3 and DVDD3 during the power up (0.8V is not a hard specification - a smaller delta between supplies is safer).
Thanks,
KW