Pmod RS485 Supply voltage 5V vs. 3.3V

[t0bi]

The PmodRS485 Reference Manual refers to the following

Quote

Any external power applied to the PmodRS485 must be within 3.0V and 5.5V; however, it is recommended that
Pmod is operated at 3.3V.

In my environment, it would be easier to run it on 5V. What are the actual disadvantages against the recommendation in operation with 5V?
Lifetime, heat, consumption...?

Thank you.

[JColvin]

Hi @t0bi,

There should be no issue running the Pmod RS485 at 5 V; the datasheet for the embedded module (https://www.analog.com/media/en/technical-documentation/data-sheets/ADM2582E_2587E.pdf) even uses Vcc at 5 V (unless otherwise noted) in its Specifications table.

3.3 V is listed in the Reference Manual since all of the Digilent system boards with Pmod Host Ports operate with 3.3 V logic, but there isn't really any difference between operating at either of the two voltages from a pragmatic functionality standpoint.

If you wanted to be technical about it, the Typical Performance Characteristics graphs in the Analog Devices datasheet indicate that operating at 5 V consumes less current than when operating at 3.3 V (based on Figure 3 and Figure 4), but that's at the cost of operating at ~100 mW higher (at least for when I looked at 20 degrees C with an RL of 120 Ohms). Whether that is something you are concerned about in your system I do not know.

Thanks,
JColvin