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BQ78350-R1: How is the precharge of bq78350-r1 prohibited?

Jason Zhao58
Intellectual 320 points
Part Number: BQ78350-R1

Hi,

How is the precharge of bq78350-r1 prohibited?The register PCHG_EN of FET Options has been configured for the bq783350-r1 never USES PRECHG.

At the same time, we see the data manual describing Setting the Precharge Start Voltage and Charging Voltage Low = 0 mVdisables the Precharge function.

But in actual use, even if we put Precharge Start Voltage and Charging Voltage Low = 0, and PCHG_EN 0, we find that the pre-charging section still has action.

  best regards,

  • 0
    TI__Guru 54715 points
    Hi Jason,
    The part has a pre-charge mode as shown in the figure in the technical reference manual section 5.1. It will always have an action as described in section 5.2.
    If you don't want to enter pre-charge mode you could move the 2 thresholds so that pre-charge mode is not entered, see section 5.2.
    If you want to use the charge FET for pre-charge, clear the PCHG_EN bit, (see page 15, the table on page 47 is incorrect).
    The Pre-Charging Current has the same range as Fast Charging Current (see page 47), so you could allow the gauge to enter pre-charge mode but the current reported to the charger would be the same.
    If you want to prevent the battery from pre-charging and the charger will follow the current from the ChargingCurrent, set Pre-Charging Current = 0 mA. If the charger will not follow the ChargingCurrent value, you can prevent pre-charge by enabling the pre-charge FET and not implementing a current path.
    Also when changing parameters, it is a good practice to reset the gauge to be sure the parameter is used, either cycle power or send a reset.