Does the device have any requirements regarding sequencing of the two supplies?
fro example, must AVDD be always larger than DRVDD?
The AD9826 comes with two separate power supply pins. We want to run AVDD from
+5V and DRVDD from +3.3V. Measuring between these pins shows a diode, which
will usually be reverse
biased, but might be forward biased, if DRVDD is larger than AVDD.
For AD9826, there is no sequencing requirement, or any requirement for AVDD to
always be > DRVDD during power-up. Our Engineers have tested this by leaving
DRVDD on while AVDD is turned off without any issues. When you say you see a
diode drop, you might be measuring the ESD protection diode(s) on the supplies.
The grounds, however, cannot be separated or there will be forward-biasing of
(This is mentioned on page 18, applications section of the datasheet).