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BQ76PL455A: Variable Cell count

Martin Haberzettl
Prodigy 40 points
Part Number: BQ76PL455A

Hello everyone,

i would like to use the BQ76PL455A Battery monitor IC with either 7 or 14 cells, depending on the application.

Obviously, it is stated in the datasheet multiple times that the upmost unused sense pins have to be shorted for the device to function correctly.
I would like to design the device without having to plan for hardware modifications that short said pins.

My question is: what is the reason for this limitation?

  • From my understanding, the Zener-diodes (5.6V @ 5mA) at the Sense inputs should prevent the pin conditions to exceed the absolute maximum ratings by leakage currents.
    May there still be a reason for damage to happen on these pins?
  • Obvously, the pins are pretty much floating DC wise due to the high input resistance. Is there a possibility this may degrade the measurements on the other channels?
  • Of course the supply for the VP pin is wired independent from the sense pins and is always connected to the upmost cell. May there still be a problem regarding the Supply?

Kind regards,

Martin Haberzettl

  • 0
    TI__Genius 11480 points
    Hi Martin,

    You are correct in the fact that the PWR input should be unaffected.

    Unfortunately, I cannot recommend leaving the cell inputs unconnected. With floating inputs, it is unpredictable what can happen. My main concern here is fallout and the device being damaged from something we are unable to foresee. As a best practice, I would strongly recommend following the datasheet.