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ISOW7841: Negative Viso

na na78
Guru 16770 points
Part Number: ISOW7841
Other Parts Discussed in Thread: UCC12050

Hi

Is it possible to make negative isolated output?

Vcc=5V -> Viso=-5V

I understand we could not use IO channel in this case.

BestRegards

  • 0
    TI__Mastermind 49835 points

    Hi,

    No, ISOW7841 cannot generate negative output of -5V. Since ISOW produces single isolated output, you can always connect VISO to your system GND and use GNDISO as -5V point. In such a use case, you will not be able to use data channels of ISOW as you also mentioned. Let me know if you have any questions, thank you.

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Guru 16770 points

    Hi Rao

    Thank you for your reply.

    >you can always connect VISO to your system GND and use GNDISO as -5V point.

    Do you mean -5V can be used in such like following configuration?

    BestRegards

  • 0 in reply to na na78
    TI__Mastermind 49835 points

    Hi,

    Yes, the configuration you have showed in the image is what I am referring to. This is not specific to ISOW, any isolated power supply can be used as +5V source or -5V source based on which pin you consider as reference.

    This is acceptable way of use, please make sure you do not use data channels. If you want to use, then you will have to match I/O logic voltages with respect to device GND pin GNDISO and not with respect system GND point ISOGND. Thanks.

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Guru 16770 points

    Hi Rao

    Thank you for your reply.

    I have noticed that UCC12050 is released.

    Could it be possible for UCC12050 to make -5V using same idea discussed before?
    (How to care SEL pin?)

    BestRegards

  • 0 in reply to na na78
    TI__Mastermind 49835 points

    Hi,

    The approach I have mentioned in my earlier post is applicable for any isolated power supply, hence I believe UCC12050 should also work fine. SEL pin for both ISOW & UCC device should be tied to their VISO or GNDISO pin based on the absolute voltage required at VISO with respect to GNDISO. Thanks.

    Regards,
    Koteshwar Rao

  • 0 in reply to na na78
    TI__Intellectual 2910 points

    Hi,

    I am the product definer for the UCC12050 device. This post is to confirm that, as Rao described, yes, UCC12050 can be used to generate a -5V isolated supply. The SEL pin should be tied to VISO pin, and the other connections as shown in the diagram above, to generate this voltage level.

    Have our posts resolved your inquiry?

    Regards,

    Daniel