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LM7310:unused pins

Hanno Reimer
Intellectual 1950 points
Part Number: LM7310

Hi colleagues, 

because the datasheet is not 100% clear here, my customer would like to know, if the set up below is OK?  

I don't want to use the Power Good. Therefore I would float PG and set PGTH to GND. I don't need OVLO either, that's why

I would put OVLO on GND. I would have EN/UVLO operated by the power good of an upstream regulator, here comes

a 1V8 logic signal (floating is avoided by high-resistance pull-down to GND).

 The device is used to supply a 9V rail (V_Out in the picture above) from two sources. Either feed in from the left

Buck regulator turns on and releases the LM73100 via EN if the voltage is valid. That would take precedence. Alternatively, PoE feeds directly into V_Out on the right,

The controller on the left would then be switched off, IN would be 0V.

 

Thanks and bye 

Hanno 

  • 0
    TI__Guru* 79181 points

    Hi Hanno,

    Please share details on customer and application. 

    This should be fine. They don't want current to flow from OUT to IN?

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 45 points

    Hi Kunal,

    I am the customer :-)

    We are planning to have a 9V buck regulator connected to IN to externally supply our application, e.g. using an AC-DC brick. OUT is connected to the 9V main rail of our application. At this point, a PoE supply (having another LM73100 at its output) will be connected. So the 9V rail may be powered either by the buck regulator on the IN pin or by the PoE circuitry having its output on the OUT pin.

    Yes, we want to prevent current flowing from OUT to IN under any circumstances, that's why we want an ideal diode.

    If I read your answer right, it would be ok to GND PGTH (PG not used) and to GND OVLO (OVLO not used as well).

    Can you confirm?

    Best,

    Thomas

  • 0 in reply to Thomas Stegemann
    TI__Guru* 79181 points

    Thanks Thomas. 

    If I read your answer right, it would be ok to GND PGTH (PG not used) and to GND OVLO (OVLO not used as well).

    Can you confirm? YES.

    Regards

    Kunal Goel