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LM5117: VCCDIS direct connection to Vout

Winston Tan1
Prodigy 130 points
Other Parts Discussed in Thread: LM5117

Hi,

With reference to LM5117, could I connect the VCCDIS directly to the Vout (12V) to reduce the power dissipation without using the voltage divider? If I'm not mistaken, the voltage divider is required when the Vout is less than 8.5V as mentioned in the datasheet.

Thanks,

Winston

  • 0
    TI__Guru 59001 points

    Hi Winston


    You can connect an external VCC source directly to VCCDIS pin without the voltage divider. Direct connection itself has no issue, but Internal VCC regulator should be disabled when the external VCC source voltage is enough high, greater than VCC UV threshold.


    Regards,
    Eric

  • 0 in reply to EricLee
    TI__Guru 59001 points

    As soon as output voltage goes up above 3V, Internal VCC regulator will be disabled and VCC voltage start decreasing.
    Switching will be stopped by VCC UV unless the output voltage goes up above 4.9V before CVCC voltage drops below 4.9V.