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LM66100: RPP in dual diode ORing application

Steve Tanis1
Prodigy 30 points
Part Number: LM66100

Section 9.2.2.1 of the 2019 datasheet mentions using a series resistor on the CE/ pin to limit the current into CE/ during a negative voltage event. What is an acceptable current to allow, or what value resistor should I use?

  • 0
    TI__Genius 10855 points

    Hey Steve, 

    Thanks for reaching out on E2E!

    You can use a 1K resistor in series to limit the current. This is a general recommendation, but isn't required for the negative voltage event.

    Thanks,

    Arthur Huang

  • 0 in reply to Alpha H
    Prodigy 30 points

    Using the LM66100EVM, I can configure the board to the diode ORing configuration that I want to use ( see Figure 9 of datasheet).

    If I connect Vin1 backwards (-3V), I get 282mA current flowing from Vin1 (with no load on Vout).

    If I remove JP7 (1K resistor between GND pin of U2 and system GND), the current falls to 1.3mA. I am assuming the current is flowing from system GND, through the 1K resistor, into U2 GND pin, through the U2 CE/ pin and then out to the backwards Vin1 source.

    Will -282mA hurt the CE/ or GND pin? Is -1.3mA an acceptable level?

    Are there advantages to placing the series resistor in the GND circuit as opposed to the CE/ circuit?

  • 0 in reply to Steve Tanis1
    TI__Genius 10855 points

    Hi Steve, 

    I checked with the design team, -282mA shouldn't be an issue and won't damage the device. How long of a duration is the RPP event?

    Thanks,

    Arthur

  • 0 in reply to Alpha H
    Prodigy 30 points

    Thank you for the information.

    The RPP event could last several minutes before the end user realized the batteries were installed backwards. Therefore, I will add a series resistor to limit the CE/ current to a point where it does not overheat the LM66100 device.