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TPS25947: AUXOFF when power is not being supplied

Part Number: TPS25947
Other Parts Discussed in Thread: TPS25948

Tool/software:

Hello,

I would like to ask you a question about the pull-down voltage of the AUXOFF pin when there is no power applied.
This is described in the data sheet, excerpted below.
The circuit configuration I am considering is shown below.
I want to determine the resistance value necessary to set the AUXOFF pin low.
However, since the low threshold of the SSM3K35AMFV MOSFET in the diagram is 0.35V (min), I want the low voltage to be 0.35V or less.
Looking at the values ​​listed on the data sheet, it appears that even if Ipg is reduced, Vpgd is 1V (max).
I would like to keep Vpgd below 0.35V including variations. Is this possible?
If possible, please tell me how many ohms the resistance should be.

Best regards,

  • Hi Kaji-san,

    We cannot do much on the VPG voltage when the device is off. If we use a resistive divider at the PG pin, the voltage can be scaled so that this issue can be resolved. Although this also looks difficult as Vth(max) is 1V for this FET.

    Just curious, are you using this FET for active low PG signal? If so, then best way forward will be either change the FET or change eFuse. TPS25948 (very similar to TPS25947) provides active low PG pin variant. You can also check that eFuse.

      

    Best Regards,
    Arush