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BQ20Z45 can't enter shutdown mode by ManufacturerAccess shutdown command when DSG FET turn on

user4357873
Prodigy 170 points
Other Parts Discussed in Thread: BQ20Z45

I completed the learning cycle and created the senc file (see attached zip file). But when I program the senc file to battery pack, do CC offset calibration, Board offset calibration, IT enable(0x0021), I found BQ20Z45 can't enter shutdown mode by shutdown command when DSG FET turn on. The battery is unsealed.

3301.BQ20Z45-4S1P-Battery.zip

Please see my test below.

1. Program the senc file to battery pack, CC offset calibration, Board offset calibration, IT enable(0x0021). CHG and DSG FET are on and current is zero.

2. Send ManufacturerAccess shutdown command, after more than 10s, battery does not enter shutdown mode as expecting. See below test waveform, DSG FET turn off for about 50ms when battery receive shutdown command, then DSG FET turn on again. It's abnormal.

3. Turn off CHG and DSG FET by FETControl (0x46), and send ManufacturerAccess shutdown command, battery enter shutdown mode.

4. Increase Deadband and Charger Present threshold, BQ20Z45 still can't enter shutdown mode by shutdown command when DSG FET turn on.

  • 0
    TI__Prodigy 680 points
    Hi,
    One of our BMS experts has been assigned to your issue and will answer shortly.
  • 0 in reply to bdefar
    Prodigy 170 points

    The Charger Present is set to 3V, do more test and find that:

    1. If BQ20Z45 is unsealed, shutdown mode cannot be entered by shutdown command when DSG FET turn on.

    2. If BQ20Z45 is sealed, shutdown mode can be entered by shutdown command when DSG FET turn on.

    3. Increase Charger Present from 3V to 12V, unsealed BQ20Z45 can enter shutdown mode by shutdown command when DSG FET turn on.

    Is there a timer that output voltage must fall below Charger Present within the time to enter shutdown mode when BQ20Z45 is unsealed?

    Please see below test waveform of unsealed and sealed, when Charger Present is set to 3V.

  • 0 in reply to user4357873
    TI__Mastermind 42535 points
    Hi,

    I think for unsealed shutdown you have to send the shutdown command twice. I believe this is noted in one of the older TRMs and this TRM may need an update. Can you please test it by sending the shutdown command twice?
  • 0 in reply to Batt
    Prodigy 170 points
    Hi,

    I have tried to test it by sending the shutdown command twice, unsealed BQ20Z45 can't enter shutdown mode. Please see my test above, when increase Charger Present from 3V to 12V, unsealed BQ20Z45 can enter shutdown mode by sending shutdown command once when DSG FET turn on. Actually, the shutdown command only need to send twice when the BQ20Z45 is sealed.