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ISOW1432: ISOW1432 VISOOUT power supply

Shuang Feng76
Expert 3310 points
Part Number: ISOW1432
Other Parts Discussed in Thread: ISOW7841, ISOW7741, ISOW1412, ISOW7821

Hi Team,

    what is the max power our ISOW1432 VISOOUT could support?

    Such as 5V output for external circuit, how much the current our device could output to supply?

    thanks a lot.

  • 0
    TI__Guru 54155 points

    Hi Shuang,

    Thanks for reaching out. ISOW1432 supports sufficient current for one standard RS-485 bus load which is 54 Ohm worstcase on the bus pins, as stated in the datasheet. This corresponds to a worstcase value of 93mA.

    Additionally, the device also supports additional 20mA current for any other loads on VISOOUT only when the device is operated with 5V input and 5V output, as stated in the datasheet.

    Let me know if you have any questions, thanks.

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Expert 3310 points

    Thanks Koti,

        My customer need to realize external circuit power supply 5V 130mA. it seems this could not be satisfy.

        any other device or work around suggestion?

  • 0 in reply to Shuang Feng76
    TI__Guru 54155 points

    Hi Shuang,

    Since ISOW1432 is an isolated transceiver, the integrated power is primarily meant for powering the transceiver. If your requirement is 5V @ 130mA then you can look at digital isolators with integrated power (ISOW77xx and ISOW78xx) which are meant to power much larger loads.

    ISOW7741 is a second-generation device and we recommend this part for your application. But ISOW7741 only supports upto 110mA at 5V output. Please do check with customer if they can manager their design with 110mA. If they have to have 130mA load support, then they can consider ISOW7841 which supports 130mA at 5V output.

    Let me know if you have any further questions, thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Expert 3310 points

    thanks Koti,

    but my customer still need below signal transfer. it seems we do not have device could satisfy their all requirements.

    any ideas for below requirements?

  • 0 in reply to Shuang Feng76
    TI__Guru 54155 points

    HI Shuang,

    Your understanding is correct, we do not have isolated RS-485 transceiver with integrated power supply that supports an external load of 130mA along with an RS-485 bus. It isn't very common to see an isolated RS-485 transceiver with integrated power supply to support large external loads.

    A good way to meet this requirement is to use ISOW1412 / ISOW1432 for isolating RS-485 and ISOW7841 / ISOW7821 to meet the additional load. I hope customer will be able to consider this approach, thanks.


    Regards,
    Koteshwar Rao