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ISOW7741: Question about using 2 ISOW7741 at the same time

Chase Jeong
Mastermind 6010 points
Part Number: ISOW7741
Other Parts Discussed in Thread: ISOW7721, ISO7740, ISO7720, ISO7730

Dear TI experts,

My customer considers ISOW7741 for their new product.

they plans to use 2 ISOW7741 at the same time, because output current of 1 ISOW7741 is small for their application.

in this case, they are wondering that it is necessary to use D1/D2 diodes to protect reverse current.

or does ISOW7741 have some protection circuit like diode itself? then my customer don't need to use D1/D2 diode.

 Please check this issue. Thanks.

Best regards,

Chase

  • 0
    TI__Guru 54885 points

    Hi Chase,

    Thanks for reaching out.

    Power supply outputs typically cannot be tied together unless the power supply has special feature (called load sharing) that allows such connection. ISOW7741 doesn't have load sharing feature and hence, doesn't allow direct connection of outputs. They can be connected using diodes as shown in the diagram you have shared but that still only allows one of them to drive the load at a time. This approach doesn't increase the output load current it adds redundancy that if one device fails the other will still support the load.

    I also like to mention that ISOW7721 has load-sharing feature where outputs from multiple ISOW7721 devices can be connected together to support higher output current. Please refer to section 9.3.4 and Figure 9-4 (also copied below) in ISOW7721 datasheet for more details. Let me know if you have any further questions, thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Mastermind 6010 points

    Dear Koteshwar,

    Thank you for your support.

    ISOW7721 that you mentioned has 2ch isolator. my customer needs 4ch isolator. Could you suggest 4ch isolator which has load sharing feature?

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Guru 54885 points

    Hi Chase,

    Thank you for inputs.

    That's right, ISOW7721 has only 2-channels and I shared this device because this is only device from our product group that supports load sharing feature. If load sharing is a requirement that you must need then I recommend that you use two ISOW7721 (digital isolator with power integrated) devices and one ISO7720, ISO7730 or ISO7740 device (digital isolators).

    I hope this works for your application, thanks.


    Regards,
    Koteshwar Rao