bq24040 charge question

Terry Wu

Expert 1680 points

Other Parts Discussed in Thread: BQ24040

Dear Sirs,

I have a 20mAH Li-battery and want to use BQ24040 charge it. Because battery spec is 1/2C or 1C(max) charging.

I don't know how to set charging current to 20mA ...

Fast charge min is 50mA <= I can't use this current to charge 20mAbattery

Pre-charge is 20% Fast charge current. But this pre-charge timer is 0.5 hour only . Even if I set pre-charge current 20mA . Can't fulfill this battery capcapacity , right ? Enter fast charge mode (100mA) will over this battery spec.

Would you kind give suggestions ? Many thanks !

over 11 years ago

0 Terry Wu over 11 years ago

Expert 1680 points

Dear Sirs,

Is there any comment ? Thanks a lot !

0 Ryan May over 11 years ago in reply to Terry Wu

TI__Genius 13700 points

Hello Terry,

I have used the BQ24040 set to lower charging currents but I disabled the termination because once the current gets small enough the device starts to approach limits in the precision with which it monitors the charging current to determine when to terminate.

With out termination the charge current will continue to taper lower and lower. You could utilize an external timer to disable charging via the TS pin.

Here is the post where I discussed using this part family at lower charging currents
:

http://e2e.ti.com/support/power_management/battery_management/f/179/p/330358/1164413.aspx#1164413

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bq24040 charge question