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TPS7H4001-SP: PWRGOOD pin

Erin Yu
Prodigy 80 points
Part Number: TPS7H4001-SP
Other Parts Discussed in Thread: TPS7H4010-SEP,

Hi Mr./Mrs.,

     After checking the reference designs of TPS7H4001-SP and TPS7H4010-SEP, the PWRGD pin is pull-high to VIN for TPS7H4001-SP while the PWRGD pin is pull-high to VOUT for TPS7H4010-SEP. Is there any concern for the difference? May we connect the PWRGD pin pull-high to VOUT for TPS7H4001-SP? (Will this lower the leakage current when TPS7H4001-SP Disabled?)

Thanks

  • 0
    TI__Genius 14540 points

    Hi Erin,

    The difference in the two designs is attributed to the abs max spec for this open drain bias on the PWRGD pin.  The TPS7H4001-SP has a max allowable bias of 7.5V on this pin which matches the abs max spec of 7.5V for the PVIN pin to which it is tied.  Therefore, no issue.  The TPS7H4010-SEP has a max allowable bias of 20V (ROC of 15V) on the PWRGD pin which is lower than the 36V max PVIN.  Therefore, this PWRGD pin cannot be tied to PVIN for applications where PVIN>15V. 

    I believe you can pullup PWRGD with VOUT on the TPS7H4001-SP but I've never measured this configuration.  If possible, I would prefer the PVIN be used as the pullup as this decouples the PWRGD monitor circuit from the VOUT node that is being monitored (via VSENSE voltage).

    Thanks

    Christian

  • 0 in reply to Christian Yots
    Prodigy 120 points

    Hi Christian,

    What is the state of the PWRGD pin when the disabled?  I'm looking to minimize leakage current from VIN since the device already draws a max supply current of 2.85mA when shutdown per the datasheet.  I'm thinking that another leakage path for VIN is the PWRGD pullup resistor if the PWRGD pin pulls it to ground during shutdown.

    Thanks

    Jim

  • 0 in reply to Jim Y
    TI__Genius 14540 points

    Hi Jim,

    When device has PVIN and VIN supplied and the EN pin is pulled low, shutdown, the PWRGD pin is pulled low.  Therefore, there will be a leakage current of PVIN/R_pullup.  You can reduce this leakage current by increasing the pullup resistor.

    Thanks

    Christian