There are three reference pins of this chip, which are REF(PIN 37), REFA(PIN
43), REFB(PIN 42). From my view, REFA(PIN 43) and REFB(PIN 42) are used for
channel A and channel B respectively and they can be offered with different
levels, if so, should REF(PIN 37) be connected? Or if REF(PIN 37) is used, is
it means channel A and channel B are using the same reference level offers by
REF(PIN 37)? Could you give us a recommended connection of these REFs or do you
have EVB schematic for AD7655? For I just have schematic for AD76xx, in which
it is hard to tell how to configure these pins of AD7655.
The AD7655 requires an external 2.5V reference applied to REF(PIN 37), REFA(PIN
43), REFB(PIN 42). The AD7655 eval board has the S31, S12 and S13 solder links
in place that connects the pin 37 (REF = 2.5V) to pin 42 and pin 43 as shown in
the AD76xx user guide’s schematic .