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LM66100: LM66100DCKR - Power-oring Schematics review

Krishnaprabha Naik
Prodigy 60 points
Part Number: LM66100

Hi All,

We are working on a Handheld battery-powered medical device that uses a 900mAh Li-Ion battery. We are using the TIs LM66100DCKR ideal diode for power or-ing between VBUS (5V USB Input) & VPACK (4.2V battery Voltage). We are feeding the output of the power or-ing circuit to the input of TIs Buck regulator TPS62821DLCR to generate 3V rail. We would like the design to be get reviewed by the TI team. Attached the snippet of the schematic implementation. Could you please review our design & provide your valuable review comments.

Thanks in advance!

Regards,

Krishnaprabha

 CC: @   Could you please have a look at this. I found from several threads that you have helped many people with Power management ICs.

  • 0
    TI__Mastermind 31175 points

    Krishnaprabha,

    Is there any potential here for a reverse battery/reverse polarity condition? If so TI reccomends a 1kohm resistor on the GND and CE pins in order to limit current going into the device during a reverse polarity event.  You can optionally put a resistor from the ST pin to the VIN pin of the priority source:

    ... and this will provide a crude mechanism of hysterisis to prevent the device from switching back and forth if the voltage teeters at the switching point.

    Other than that everything looks to be in order. 

  • 0 in reply to Timothy Logan
    Prodigy 60 points

    Timothy Logan,

    Thanks for your feedback.

    No, the reverse polarity protection is not required here since a standard connector (not wire leads) is used for connecting the battery to the board. Since we will not get into a case where both voltages are the same (because one input is from USB which is 5V always, another input is 4.2V(max battery voltage) which is always less than 5V), we don't need to connect from the ST pin to VIN with the resistor.

    Thanks for your valuable review comments.