Question
Digital supply voltage is specified in table as 2.7Vmin to 3.6Vmax. But in
several places in the text, the data sheet says the digital supply can be
run at 2.5V. I would like to use a 2.5V Vdd supply - is it safe for me to
do so and what voltage tolerance is acceptable?
Answer
Pins marked VD are the analog supply and must be at least 2.7V in order to
achieve specified spurious and SNR performance. Pins marked VDD are the digital
supply which consists mainly of the databus output drivers and can be as low as
2.5V.
The intention is to make the AD9218 extremely simple to *interface* the AD9218
to 2.5V logic circuits.
It is possible to power VD from 3V +/-10% and VDD from 2.5V. In this case
you get guaranteed AC performance and output logic levels which interface
directly to 2.5V CMOS logic.