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ISO1410: B version of part has receive pin stuck high

Paul Zwart
Prodigy 30 points
Part Number: ISO1410

Tool/software:

We have a circuit that uses the ISO1410 which closely resembles the evaluation board offered for the ISO1410. We bought part number ISO1410BDW for this circuit instead of part number ISO1410DW that is in the evaluation circuit. According to the datasheet, the only differences between these parts is the level of isolation. 

Testing the circuit we found that the receiver output on the logic side of the IC was being held high even when it was enabled by pulling the RE pin low and having a good differential signal coming in. We used the same input signal and pull down on the enable pin on the evaluation board and it worked correctly. After not being able to find anything different between our circuit and the eval board, we moved our IC onto the evaluation board and now the evaluation board also does not work (implying the problem is with the IC itself). We have 7 copies of this same circuit and they are all exhibiting the same issue, so it doesn't appear to be a damaged component. Is there anything significantly different on the "B" part that could cause this difference in operation? 

Thanks,

Paul

  • 0
    TI__Genius 15035 points

    Hello,

    Please give us an additional 24 hours to respond.

    Regards,
    Aaditya Vittal

  • 0 in reply to Aaditya V.
    TI__Mastermind 25690 points

    Hello Paul, 

    You are correct, the only difference between the 'B' version and the non-'B' is the level of isolation. There is nothing about the 'B' device that would cause the difference in operation. The 'B' is not a revision of the part, instead it denotes basic isolation ratings (not reinforced). I would recommend sending a switching waveform on the RS-485 bus lines and see if the receiver responds while "R" is enabled and held low. DE should be disabled (held low) during this time to ensure there is no bus conflict. 

    Best,
    Andrew