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MAX3221: RX working TX not working.

Part Number: MAX3221

I am using MAX3221MDBREP in my design. It was working fine. Suddenly is not working. When i checked with DSO, RX side is working ( RS-232 level to TTL level).

But TX side is not working (TTL level to RS-232). Getting 0 Volts at TX pin (DOUT). While visual inspection the top of the IC has brown color as it got heated somehow.

What could be the reason??

  • Francis,
    After the failure, can the device recover or is TX just 'dead' ? You can check the voltage level of V+ or V- pin of the device. If they're zero, it means the TX port might be damaged. If it's the case, it's hard to say where the problem was for now. But in some applications, this happens if DOUT pin accidently gets short to a DC supply, or some ESD event occurs. BTW, MAX3221E is the device has same function but better ESD protection level.