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Original question:

BQ24170: Input current drop issue

BQ24170: Charging time and TTC setting

PYTsai
Genius 11665 points
Part Number: BQ24170

Hi 

We set the TTC as below 

tTTC= CTTC x KTTC = 0.1uF x 5.6 min/nF = 9.3hr

However when charging a 2 cell battery from 6.42V to 8.36V it only take 4.5 hours. 

Our schematics attached below. 

May i ask what will impact the charging time ?  thanks!

bd100_20190213.pdf

  • 0
    TI__Guru**** 166866 points
    Hi PTYsai,

    The tTTC sets the safety timer. It stops charging a damaged battery after time out. Your charge time can be estimated as battery capacity/charge current * 1.3 where the 1.3 accounts for time in constant voltage (CV). CV time might be longer if your battery is higher resistive or if you have a highly resistive connection from the charger's output pin to the battery.

    Regards,
    Jeff