BQ24133: Question regarding charging

SUNGMIN PI

Prodigy 90 points

Part Number: BQ24133

Tool/software:

Hello, thank you as always for your help.

I have a question regarding charging behavior.

When I charged a 1,800mAh lithium-ion battery, the LED turned off properly upon full charge, as expected.

However, when I charge a 3,000mAh lithium-ion battery, it seems to reach almost full charge, but the charging current remains at around 600mA, and the LED turns off very briefly, then turns back on and stays on. This behavior repeats several times, and eventually, the LED enters a BLINK state.

Here, the fast charging current is 1.5A, and the TTC is HIGH.

I would appreciate your insight on this.
Thank you again for your continued support.

8 months ago

0 Christian Moyer 8 months ago

TI__Mastermind 39111 points

Hello SUNGMIN,

The image is not loading, Can you re-upload the image?
Can you provide the schematic?
What is the input voltage?
What is battery voltage when this issue occurs?

Best Regards,

Christian

0 SUNGMIN PI 8 months ago in reply to Christian Moyer

Prodigy 90 points

The input voltage is 5V.
The problem occurs shortly before the battery becomes fully charged.

0 Christian Moyer 8 months ago in reply to SUNGMIN PI

TI__Mastermind 39111 points

Hello SUNGMIN,

SUNGMIN PI said:
The problem occurs shortly before the battery becomes fully charged.

What is the measure battery voltage at this point?

Do you have a system load when this issue occurs?

The LED is either blinking because of fault condition below

the charger is going into charge, terminating, recharging, repeat.

Can you take an oscope shot of STAT, PVCC, VBAT and SW when the issue is occuring and when the issue is not occuring? On the blinking plot, I would like to see at least 3 blinks.

0 SUNGMIN PI 8 months ago in reply to Christian Moyer

Prodigy 90 points

Thank you always, Mr. Christian Moyer.

Q : What is the measure battery voltage at this point?

A : The battery voltage at the time the issue occurred was between 4.1 and 4.2 volts. However, the test was conducted with a battery that was already nearly fully charged. Therefore, when the test was conducted with a battery at approximately 3.7V, the battery voltage at the time the issue occurred was around 3.8V.

Q : Do you have a system load when this issue occurs?

A : There is no load connected.

Q: Can you take an oscope shot of STAT, PVCC, VBAT and SW when the issue is occuring and when the issue is not occuring? On the blinking plot, I would like to see at least 3 blinks.

A :

This photo shows the waveform of the SW pin during battery charging.

During testing, I observed another phenomenon that seems related. As the battery charges, the current gradually decreases, and at some point, the LED turns off and then turns back on, after which it appears to resume charging. This behavior repeats several times, and eventually, I noticed the LED entering a blinking state.

If the safety timer is not used and only charge termination (pull-up) is used, could this cause such problems?

Thank you for your continuous support and assistance. I appreciate all your hard work.

0 Jeff F 8 months ago in reply to SUNGMIN PI

TI__Guru**** 173206 points

Hi Sungmin,

If the LED was blinking and then finally stopped, I would expect the issues is the problem as explained at

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1220405/faq-bq24105-why-does-the-battery-charger-s-output-voltage-and-current-show-several-pulses-before-charge-termination?tisearch=e2e-sitesearch&keymatch=bq24105%20faq#

I am puzzled by your scope plot showing VBAT measuring 5V? It should no higher than 4.2V, yes? Can you double check that measurement?

Regards,

Jeff

Power management

Power management forum

BQ24133: Question regarding charging