I am planning to use AD7626 in echoed-clock interface mode for my design. I have 2 queries:
1. What decides the choice for the reference voltage - (a) Internal 1.2V, (b) External 1.2V at REFIN, and (c) External 4.096V at REF.
2. Referring to page 6 of the AD7626 datasheet, how much before the CNV pulse will the CLK pulses need to be sent to the AD7626 for the conversions. There is no mention of this, even though it is shown that the CLK pulses are sent before the CNV pulse.