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BQ25180: What will the charging status be after precharge safety timer expires

John Griffith
Mastermind 21811 points
Part Number: BQ25180

Tool/software:

Hello,

If a overly discharged battery is connected (VBAT<VBATSC), my understanding is that the device will charge the battery at the rate of IBATSC for up to VLOWV. During this time, my understanding is that the CHG_STAT bits in the STAT0 register will be 2b01 during this time. If this timer were to expire, would the device's charging status bits change to 2b00? 

Thanks,

John

  • 0
    TI__Mastermind 18015 points

    Hi John,

    Yes I believe it does provide a change in CHG_STAT but I will confirm this in lab and provide a response.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    TI__Mastermind 21811 points

    Thanks! Keep me posted on what you find. 

    John

  • 0 in reply to John Griffith
    TI__Mastermind 18015 points

    Hi John,

    Just confirmed, CHG_STAT does report 2b00 "Not Charging while Charge is Enabled" and STAT1 indicates the SAFETY_TMR_FLAG is set. Just a reminder to the customer, once the SAFETY_TMR_FLAG is read it auto-clears so it's important that it is captured the first time it is read.

    Best Regards,

    Juan Ospina

  • 0 in reply to Juan Ospina
    TI__Mastermind 21811 points

    Hi Juan,

    Thanks for verifying this in the lab! Follow up question:

    My remaining question regarding the “Not Charging while Charge is Enabled” state is this: once in this state, is there any instance where the BQ25180 will re-attempt to charge the battery automatically, without a change in external states? (e.g. host toggling off/on charging in the ICHG_CTRL register, VIN removed and then reapplied)

     Figure 8-1 indicates that “Charging or VIN toggled” must be TRUE for Precharge or FastCharge to resume. I assume a similar state flow exists for over- or under-temperature conditions preventing battery charge, where charging will not resume unless the battery pack temperature returns to the region between the TS Hot and TS Cold limits of the TS_CONTROL register.

    To be clear, if the BQ25180 winds up in the “Not Charging while Charge is Enabled” state (as noted by the STAT0 register), is there no instance where it will exit that state -- unless some external influence (ICHG_CTRL register, VIN source, battery pack temperature) changes?

    They basically want to not program the device at all but want to ensure that it won't retry charging for any reason other than externally resetting or telling the device to try again.

    John

  • 0 in reply to John Griffith
    TI__Mastermind 18015 points

    Hi John,

    For TS related faults, the device will not continue charging until the fault condition is resolved, regardless of charge enable / disable.

    John Griffith said:
    To be clear, if the BQ25180 winds up in the “Not Charging while Charge is Enabled” state (as noted by the STAT0 register), is there no instance where it will exit that state -- unless some external influence (ICHG_CTRL register, VIN source, battery pack temperature) changes?

    This is correct, if a fault is present then either the fault must be cleared or an external action (such as charge enable toggle) must take place to continue chargingin.

    Best Regards,

    Juan Ospina