BQ21040: No charging as expected

Weston Wood

Part Number: BQ21040

I have a BQ21040 charging IC connected as the data sheet describes. I am using a 10kohm resistor instead of the temperature sensor, the setting resistor is a 750ohm resistor and are expecting a quick charge current between 700 and 800 mA. The battery that is being charged is a 1200mAh 3.7v lithium polymer battery. So far we have been getting a constant current of around 105mA. Any help would be appreciated.

over 6 years ago

0 Bill Johns over 6 years ago

TI__Guru* 75806 points

Hello
Take a look at FAQ Post which has some troubleshooting ideas that apply to the BQ21040 also.
e2e.ti.com/.../763227

Also check figure 7 in data sheet.

0 Bill Johns over 6 years ago in reply to Bill Johns

TI__Guru* 75806 points

Hi

Any update on this problem?

0 Bill Johns over 6 years ago in reply to Bill Johns

TI__Guru* 75806 points

Hi
Are you still seeing the low current during charging problem?

In addition to the FAQ other things to check:
1.) What is voltage on ISET pin -- when in CC mode the voltage will be 1.5V. During CV mode it will drop below this point. Raito of ISET current to output current is 1 to 360.
2.) Thermal rise of the device -- Does unit seem to be heating, when die temp reaches 125C the output current is reduced
3.) Input voltage drop -- If input voltage drops under load output current is reduced.

Hope this help, let me know how I can assist.

0 Bill Johns over 6 years ago in reply to Bill Johns

TI__Guru* 75806 points

Hello
I hope you were able to resolve the problem.
I will close this thread now, however please reply if you have further questions on this subject.
Or post a new thread with new questions.

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BQ21040: No charging as expected