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ISO1050: https://ticsc.service-now.com/csm?id=csm_ticket&table=sn_customerservice_case&sys_id=9bbb5170dbf2581056e4d7b2f396197a&view=csp

Tamas Vashegyi
Prodigy 20 points
Part Number: ISO1050
Other Parts Discussed in Thread: ISO1500, ISO1410

Can I use the ISO1050DUB chip to receive RS485 balanced signals?

I.e. The RS485 driver input is a TTL 100 ns negative puls, the output of the RS485 driver is a +100ns puls and a -100ns puls. Can I use these two signals as input canHigh and canLow on the Can-Bus side of an ISO1050DUB receiver?

There is no can protokol, just a single puls, point to point connection.

I need an isolation an don't want to use opto-couplers. The ISO1050DUB receiver can-side (canHigh and canLow) is +5V, the ISO1050DUB receiver output side ( single signal) is +3.3V.

  • 0
    TI__Mastermind 49495 points

    Hi Tamas,

    Welcome to TI E2E Forum!

    The ISO1050 is not designed to support RS-485 signals even though both CAN and RS-485 are differential communication interfaces. Though we have never tested the ISO1050 with an RS-485 input, it looks like the CAN device will be able to pass the pulse that you have described. Though this seems like going to work, there seem to be a few issues here. The polarity of RS-485 and CAN bus signals also being opposite to each other also makes it a little complicated.

    I am assuming you are connecting the positive RS-485 terminal to CANH and negative RS-485 terminal to CANL. When the 100ns negative pulse is applied at RS-485 input, the output will also show up a differential negative pulse. For ISO1050, a negative differential pulse (RECESSIVE state) on CAN bus will produce a HIGH at the output (R pin). After the negative pulse is over on RS-485 device, I am assuming the bus stays HIGH for the rest of the time. This is going to be a DOMINANT state for CAN and in about 450µs (typical) the ISO1050 will hit dominant time out condition and hence will release the bus.

    Any specific reason why you want to ISO1050 to be interfaced to RS-485 bus? We do have quite a few isolated RS-485 transceivers. ISO1410 & ISO1500 are the two latest RS-485 isolators that can be interfaced to any RS-485 bus without any issues. Let me know, thanks.

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 20 points

    Hi Koteshwar,

    thank You the nice answer. To tell You the truth I read some info on the CAN isolator and that time came the idea. I didn't know about the above mentioned ISO1410 or ISO1500. I think I will use probably the ISO1410 and will be a perfect solution.

    Thank You again for your help!

    Regards,

    Tamas Vashegyi

  • 0 in reply to Tamas Vashegyi
    TI__Mastermind 49495 points

    Hi Tamas,

    Thank you for your inputs and glad to know that ISO1410 will meet your requirements.

    Regards,
    Koteshwar Rao