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Original question:

BQ40Z50-R1: BQ40z50 PBI PIN

BQ40Z50-R1: BQ40z50 PBI PIN function

Hollis Liu
Intellectual 2535 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50

Hi team,

If we short the PACK+ to GND, will the PBI pin CAP provide a transient back up power to make bq40z50 protection fuction work well?

If we assume the BAT pin votlage is also 0 when short circuit happened, how long will the PBI CAP make the bq40z50 work well？What will bq40z50 do at last, to store some RAM?

  • 0
    TI__Guru 52115 points

    Hello Hollis,

    The bq40z50 PBI pin is the power supply back-up input for handling line transients, it cannot sustain driving the charge pumps. A quick test you can do is scope VS4/3/2/1 to VSS and PBI pin. Trigger the scope on the falling edge of the cell supply to the chip and monitor the fall time of the PBI pin. It will be on the order of milliseconds. ~10 ms.

    The bq40z50-Rx, once it loses power will not store any RAM. The RAM contents get reset upon a full POR.