I have two ADM3222 in parallel, but the RS232 signle is not working correctly if one of the ADM3222 is powered off, why is it?
As RS232 is designed for point to point operation, it is not recommed to have trancivers in parallel.
This issue is due to Tx architecture. ADM3222 has low impedance on Tx when powered off.
A workaround would be adding two NMOS FETs on the signal line, as shown attached.
Same question, but with the ADM322 powered up but with receiver three-stated and in shutdown.
What about the CMOS signals under the same conditions.
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