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BQ24165: How to detect the state for safety timer of BQ24165?

Tess Chen
Intellectual 2675 points
Part Number: BQ24165
Other Parts Discussed in Thread: BQ25606

Hi,

I use the BQ 24165 to charge a single cell 46Ah Li-ion battery, Vcharge=4.2V.  R=330ohnm (1.5A) between ISET and GND. As the safety timer is limited about 6h(typical 360 min), but the charge time for full charge is more than 6h.  So the charge cycle stoped  after 6h for my battery to charge from 3.7V to 3.996V and is not full charged. Another logic should be added to enable CE1 and CE2 and start another charge cycle while I am not willing to.

 1. The time for safety timer can be modified or not?

  2. Does there any pin can detect the wrong state for output ? CHG is just the indicator for charge cycle

  3. Does there have a  longer safety timer device which is pin-to-pin compatible to BQ24165?

Thanks a lot.

 

  • 0
    TI__Guru**** 153436 points

    Hi Tess,

    Regarding 1, the IC automatically doubles its safety timer to 12 hours if it is input current limit (IINDPM), input voltage limit (VINDPM), TREG or JEITA WARM or COOL.  Since the BQ24165 has /CEx pins, presumably for the host to tell the charger to run in JEITA WARM or COOL, if you set /CE1=1 and /CE2=0, the charge timer is now 12 hours, but VBATREG is reduced to 4.06V.  Do you have a way to monitor the battery voltage so that you can change /CE1 to 0 when V(BAT) is slightly below 4.06V?  If not, maybe a resistor divider from the battery to the gate of an NFET (poor man's comparator) with drain pulled up to DRV through a resistor and connected to /CE1?

    Regarding 2, no.  Only the /CHG and /PG provide IC status.

    Regarding 3, unfortunately, no.  If you choose to change ICs and don't need dual input, you might consider the BQ25606 3-A charger that has a 10 hour timer.

    Regards,

    Jeff