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UCC28950: Whether the VREF pin can power other devices

Kaji@PAN
Mastermind 7815 points
Part Number: UCC28950
Other Parts Discussed in Thread: UCC28070, ISO7710, UCC28951, PMP8787

Hi,

I previously asked the following thread about the circuit that synchronizes UCC28950 and UCC28070.
I am considering using ISO7710 to synchronize both devices.
But I need to think about how to supply ISO7710 power.
I think UCC28070 VREF cannot be used, so UCC28070 side will make another power supply.
I think the UCC28950 VREF can power ISO7710.
Is my opinion correct?
Or does the UCC28950 side need to make another power supply?

Best regards,

e2e.ti.com/.../886390

  • 0
    TI__Mastermind 25570 points

    Hello Kaji-san

    You are correct the VREF of the UCC28070 isn't really strong enough to supply current to the ISO7710 device. It has a maximum rating of 2mA and we recommend that the current be kept below 500uA. This is enough to feed the potential divider at PKLMT etc but not enough for other purposes.

    The UCC28951(0) can supply up to 20mA from its VREF output which should be enough to supply the ISO7710 device - be sure to include the currents needed to feed the EA+ potential divider when you calculate the current needed from VREF.

    Our PMP8787 reference design would be a good starting point for a design for the aux rails needed to power the primary referenced side of the ISO7710 device - details are at http://www.ti.com/tool/PMP8787

    Regards

    Colin