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bq24630 - how to force a recharge cycle

Steve Patterson
Intellectual 570 points
Other Parts Discussed in Thread: BQ24630, BQ34Z100

We need to be able to force the bq24630 charger to initiate a charge cycle. The part has a CE (Charge Enable) input, when high enables charging cycles to start and when low stops/prohibits charging cycles. The datasheet has the following statement (with my highlights), but with no follow-up details:

“A new charge cycle is initiated and the safety timer is reset when one of the following conditions occurs:

  • The battery voltage falls below the recharge threshold.
  • A power-on-reset (POR) event occurs.
  • CE is toggled.”


Does this mean that the (false-to-true?) “edge” of the CE input forces a charge cycle to start? If not, can one force a charge cycle to be started?  How long of a transition is needed to be interpreted as a "toggle"?  

Ideally, we would like to program a bq34z100 Alert output to force the bq24630 to start a charge cycle when the fuel gauge sees the alert SOC we program into it, without SW intervention after the set up. Thanks for any info on this.

  • 0
    TI__Genius 11480 points

    Hi Steve,

    I believe you have the right idea. Pulling CE low, or letting it float, will disable charging. Pulling it high will enable the charging. If you look at the charge enable (Figure 2) plot of the data sheet, it shows that CE must be high for ~1.5 seconds to enable charging. The charge disable curve (Figure 4), shows that it takes only several microseconds. 

  • 0 in reply to David Wiest Jr
    Intellectual 570 points

    Thanks David.  I appreciate the quick response.  The question under the question is - will the bq24630 initiate a charge cycle after recognizing the CE transition from false to true even if its voltage measurement doesn't indicate the battery needs it?  We want to maintain a minimum SOC in the battery, which is higher than the bq24630 would normally operate at, so we want to "force" the bq24630 to start the charge cycle.  Thanks for any further detail!

  • 0 in reply to Steve Patterson
    TI__Expert 8690 points

    Hi Steve,

    As long as your system is okay with all the criteria at datasheet 8.3.7 section to enable charge, you can toggle CE to force a new cycle. The bullets on section 8.3.5 of the datasheet also confirm that CE toggle will restart a new charge cycle. I do not have the exact time needed for a CE toggle, but 50ms low time should be enough.

    Regards,
    Steven

  • 0 in reply to Steven Bangdiwala
    Intellectual 570 points

    Thanks Steven.  That completely answers my question.