Qthe data sheet for the ADM2484E device lists the voltage supply range for VDD1
from 3.3V to 5V. The VDD2 supply is rated 3.3V. On page 16, observing Table 7
we can see VDD1 is rated to 7V max, however VDD2 is rated up to 6V.
We were lucky enough to end up with a design that supplys VDD2 with 5V. We of
course undestand that this is out of specification, but we wonder how bad is
it? Can we expect premature failure or maybe just some of the specified
parameters will be worsend?
ACorrect, the implications of operating outside the recommended conditions are
that the part will be outside normal specifications and reliability may be
impacted (as per the explanation under the absolute maximum ratings section).
The RS-485 transceiver inside the ADM2484E is designed to be powered by 3.3V
(hence the requirement for Vdd2, the transceiver is on that side of the device).
The ADM2491E is a pin-compatible part that is intended to be powered by 5V on
Vdd2, perhaps replacing with this device (in the same application circuit)
would be a suitable option for you. One difference is that the ADM2491E
supports data rates of up to 16 Mbps, so unlike the ADM2484E, the driver output
edges are not slewed.