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BQ78350-R1: Undervoltage detection for record a PF after shutdown , used with bq76920 (AFE) and bq76200PW (High-side n-channel FET driver)

Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76920

With bq78350-R1, it's possible to program a cell voltage to shut down the chip and a voltage for the undervoltage Permanent Fail.

If the shutdown voltage occurs before the PF voltage, the bq go in shutdown and can’t detect an undervoltage PF that would occur later.

To wake up the bq (We don't have an accessible pushbutton on TS1 bq76920), we use the charge voltage to generate a pulse on TS1 (there is no communication with the charger).

When the charger is connected (charge voltage is present) --> the bq76920 wakes up (pulse generated on TS1 with charge voltage), wake up the bq78350-R1, activates the MOSFETs. The cells charge immediately and their voltage increases rapidly, which does not allow to detect an undervoltage PF, if it is present.

 Our goal is to put the bq in shutdown, in order to maximize the time before the next charge, but to be able to detect if cells are too discharged when the bq wakes up (with the charger voltage).

 Questions:

  1. Is the sequencing after the -->  correct?
  2. Is there a possibility to configure a waiting time between the wake up and the activation of the charge mosfet in order to be able to detect an undervoltage PF?
  3. Do you have another solution by using Keyin input for example ...Or delay a signal on bq76200PW?
  4. Or do we only have the choice between Shutdown or CUV PF + Shutdown PF?

Thank you in advance for your answers.