• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 257 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ24171: TTC function question for BQ24171

Tess Chen
Intellectual 2675 points
Part Number: BQ24171

Issue: BQ24171 take long time to charge after reach 96% capacity. Does this have any relation with TTC function?

Questions:

1. If the TTC direct connect to ground, does the fast charging safety time and  the end current safety time all turns to 0?
2. TTC ground-to-ground capacitor time (5.6min / nF x 100nF =560min), is the fast charging time or the full charge time ?
3. If the TTC direct connect to ground, what are the risks？

  • 0
    TI__Mastermind 40325 points

    Hello,

    Pull the TTC pin LOW to disable the fast charge safety timer and to disable termination.

    The calculated time is just for fast charging time.

    Disabling the fast charge safety timer will let the battery continue to charge past the maximum programmed time limit. Disabling termination will cause a longer CV phase because charge will continue to be in progress.

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.

  • 0 in reply to Michael Emanuel35
    TI__Intellectual 2675 points

    Hi Mike,

    Lithium battery charging can not be up to 100% issue found, please help me to confirm below understanding is correct or not:
    From the following TS temperature, battery charging is accompanied by a temperature rise (ambient temperature is also related), if to 45 degrees or higher, and the FB voltage will change (2.1V--->2.05V, or 2.025V).
    In this situation, the output voltage cannot reach the maximum voltage value (default is 8.7V@FB x 2.1V, 8.49V@FB x 2.05V).

    Thanks.

  • +1 in reply to Tess Chen
    TI__Mastermind 40325 points

    Hello,

    If the battery gets to a temperature to the point that T3 is met at TS, the FB voltage will change from 2.1 V to 2.05 V. If the battery gets to a temperature to the point that T4 is met at TS the FB voltage will change from 2.05 V to 2.025 V. If T5 is met charge is suspended.

    I mentioned this in terms of T3 T4 and T5 because the temperature is not necessarily 45 C, 50 C, and 60 C. It will depend on your chosen thermistor and the desired temperature range (ie what resistor divider you make).

    If the feedback voltage changes you will not be able to meet the maximum voltage because the battery will be too hot as determined by the TS pin.

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.