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LP3876: What will happen to Vout when the "SENSE" pin is floating

Cedrick
Expert 8270 points
Part Number: LP3876

Hi,

Greetings.

Our customer is designing a regulator with sense using LP3876 regulator. The VOUT and SENSE will connect through connector to UUT.

Now, they want to know what will happen or what will be the value of Vout if the connector was bent and cause the SENSE pin to float?

Looking forward to your response. Thanks



Regards,

Cedrick

  • 0
    TI__Mastermind 33785 points

    Hello Cedrick,

    If the SENSE pin is unconnected, then the feedback will be broken.
    Running a linear regulator in open loop will cause the internal error amplifier to turn on the pass element as hard as possible until it is in saturation.

    This will have the effect of passing almost all of Vin to Vout.
    If there is any current draw on the load then some voltage drop will occur across the internal pass element, which is a PMOS in this case.
    So Rds_on * Iload = Vdrop.  Vout = Vin - Vdrop.

    Thanks,

    - Stephen