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TPS7H1101A-SP: Grounding Unused Pins

Richard Y.
Prodigy 50 points
Part Number: TPS7H1101A-SP

Tool/software:

Is it OK / any risk to ground unused pins such as PCL, CS, PG/OC, and SS?

  • 0
    TI__Expert 7655 points

    Hi Richard,

    Grounding SS will hold the device in a disabled state.

    PG can be left floating externally since it is an open-drain output.

    Grounding CS will disable the foldback current limit mode, which would cause more power to be dissipated in the case of an overcurrent fault. Grounding PCL will set the current limit threshold at an extremely large value, which could cause damage to the device in the case of a high-power dissipation event. I would generally recommend using resistors on these 2 pins for the added protection, but can look into whether they are 100% necessary. 

    Thanks,

    Sarah

  • 0 in reply to Sarah Koch
    Prodigy 50 points

    Hi Sarah, our application requires that any unused pins be terminated to GND or pulled high/low. Assuming we can assign values to CS/PCL, what do you recommend we do if we do not require a soft start and PG?

  • 0 in reply to Richard Y.
    TI__Expert 7655 points

    Hey Richard,

    Based on the Electrical Characteristics table, any external pullup on SS should not exceed 1.188V. Is there any particular reason you don't want to use Soft Start? If not, then it would be simplest to use a capacitor on that pin as is typically done. This generally leads to a gentler startup and addresses challenges caused by inrush current (and power/heat dissipation if current limit kicks in due to this). 

    Similarly, you could configure PG with an external resistor to pull it up to a high voltage(typically VOUT, but can be a different rail). 

    Thanks,

    Sarah