Champs,
So if I power the VDDP pin with 1.8V on the TCA6408- can I have pullups to 2.8V if configured in open-drain mode? Normally I would have said this is a no-no in IC design; but if its truly open drain then maybe this works. The 'functional diagram' is the datasheet only shows the ESD diode to GND and not one to the rail, which would be typical of a true open-drain output; but thought I'd ask if there would be an issue doing this. I think my customer is really trying to ask if they can mix- that is; that they'd have some I/Os pulled to 2.8V, others to 1.8V; but have used 1.8V as the VDDP for the part. It also sounds liek the question may have been asked of me after layout was done and boards assembled; because otherwise I would have thought you just would use 2.8V as the VDDP; but please advise if it's possible to pullup outputs to a VDD higher than VDDP if using open-drain mode.
