BQ25306: Operation Without Battery

Oscar Saldaña Mendez

Prodigy 20 points

Part Number: BQ25306

Dear TI Team:

I made the following standalone battery charger design using BQ25306:

The PCB design was as follows:

The PCB is functional, charges the battery completely and then the charger turns off until it detects low battery. However, my question is the following, when I connect the external power and connect the battery, I get 8.4V at the charger output. But when I connect the external power and do not connect the battery, the output voltage of the charger is 2.2V, is this normal? Do you always need to have the battery?

Note: the charging circuit is always connected.

I look forward to your kind comments.

Thanks and Regards

3 months ago

0 Garrett Kreger 3 months ago

TI__Mastermind 21685 points

Hi Oscar,

The BQ25306 is not designed for use without a battery. With no battery connected the output is being regulated to 2.2V which is the Vbat_short rising threshold. The Vbat_short spec can be found on page 9 of the datasheet.

Best Regards,

Garrett

0 Oscar Saldaña Mendez 2 months ago in reply to Garrett Kreger

Prodigy 20 points

Dear Garrett:

Thanks for the clarification, analyzing the datasheet I can see that I can implement a *Power Path* to make the charger work without a battery.

Regards

+1 Garrett Kreger 2 months ago in reply to Oscar Saldaña Mendez

TI__Mastermind 21685 points

Hi Oscar,

Yes an external power path utilizing an external FET is an option to make BQ25306 charger work without a battery connected. Apologies I should have pointed this section of the datasheet out in my previous response.

Best Regards,

Garrett

0 Oscar Saldaña Mendez 2 months ago in reply to Garrett Kreger

Prodigy 20 points

Dear Garrett:

Thanks for the information, I will take it into account for the second version of the design.

Regards

Power management

Power management forum

BQ25306: Operation Without Battery