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SN75182: SN75182 line receiver

Lorenz Schmitt
Prodigy 10 points
Part Number: SN75182

I have a problem with  the SN75182 line receiver. In general,  the circuit works and the received messages at the output pin 6 are OK . But after a few weeks, the circuit is defect and I have to replace it by a new one. This happened the 4. time.

Pin 1 and 3 are connected to the RS485 lines. Between pin 2 (RT) and pin 1  a 3,3 nF capacitor is connected. Pin 4 (STRB) and pin 14 are connected to +5V.  Pin 6, the TTL output  is connected to the RxD of an Microprocessor.  Pin 7 is connected to ground. All other pins are not connected.  I assume the problem at the input side of the chip, not at the TTL output.

What could be wrong with my design ?

Lorenz

  • 0
    TI__Guru 62910 points
    Hi Lorenz,

    Sorry to hear about the problem you're having. I don't see an issue with the usage you described, and so I am wondering if it is possible that these devices were somehow damaged during operation (e.g., due to overstresses like electrostatic discharge, etc.).

    Do you have any more details on how the failing devices behave? For example, is the output stuck high or stuck low, or does the part act like as if it were unpowered completely (with high-impedance outputs)? Are you able to observe any changes with respect to supply current or input pin impedances? Do any pins appear shorted to ground/5-V or other signals within the IC?

    Regards,
    Max