BQ40Z50-R2: LED Display during Charging

Zhihan Zhang

Part Number: BQ40Z50-R2

Hi TI Team,

I'm currently using 4 LED with 20% segment for SOC indication. I set LEDCHG, but not BLINKMIDPT. And I found that during charging, for example at SOC = 80% ~ 99%, LED4 is blinking not solid until 100%, which seems not exactly match the description in sec 8.1.6 of TRM. Is this as expected or I missed something for the LED setting?

Also, I found that after I stop the charging before FC (e.g. just stop charging at SOC = ~96%), LEDs remain on for roughly 60s which is quite long. Is that possible to decrease this period to e.g. 1s?

Thanks,

Zhihan

over 4 years ago

0 Wyatt Keller over 4 years ago

TI__Guru** 105600 points

Hello Zhihan,

Can you share your .gg file so we can take a look at your settings? You're not using the BLINKMDPT function?

This thread may be helpful for you: e2e.ti.com/.../3524517

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Please kindly review attached. BLINKMDPT bit is not set.

Also I've read the thread you shared and adjust Chg Relax Time to e.g. 5s. And it seems it does lower the LED on period to ~5s after I stop the charging. So my question is, will lower Chg Relax Time to e.g. 1s which is preferred bring some side effects? Since default is 60s.

And just curious, 60s is much longer than default 1s of Dsg Relax Time. Is there any particular reason the default time for Dsg and Chg Relax Time are so significantly different?

Thanks,

Zhihan

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105600 points

Hello Zhihan,

I think there may have been an issue if you tried to upload the .gg file.

Some of the concerns were outlined in the post linked, you would not want to the current lingering around the quit current threshold because it can enter/exit relax mode quicker with the delay decreased.

The longer relax time is most likely to reduce the chance that you enter RELAX mode while current is flowing from the charger.

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Thanks for your reply!

I did check the reference link you shared and seems I have mostly same question. So basically Chg Relax Time is related to LED on time after charge stops. So what would be the recommended minimum value for this time threshold? Our customer would want the LEDs off 1s right after charge stops, so not sure if set Chg Relax Time to 1s would be too fast?

I uploaded my .gg file again. Please kindly check.

Thanks,

ZhihanLED.gg.csv

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105600 points

Hello Zhihan,

The chg relax time can be set lower, I would not set it as low as 1 second, 5 second would be better if possible.

In your LED config you have LEDRCA and LEDPF0 on, I would disable those functions and then test again to eliminate the possibility that those are triggering the flashes.

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Thanks for your advice! 5s will be ok.

I also disable LEDRCA and LEDPF0, then charge the battery again. Still, the first LED is flashing or blinking. RSOC is ~48%. 4 LEDs are used. During charging, LED1 is solid, while LED2 is flashing, not solid. Please advise.

Thanks,

Zhihan

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105600 points

Hello Zhihan,

Can you share the edited gg file so we can take a look?

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Please kindly review attached GG.

Thanks,

Zhihan

617 LED.gg.csv

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105600 points

Hello Zhihan,

I uploaded your .gg file and tested with my EVM, it did not happen when I used the DISP button, is this only occurring when you start the charge?

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

Yes, this only occurs during charging, the LED that represent the current SOC is flashing. For example, 4 LEDs config with 25% segment each, at 45%, LED1 solid, LED2 flashing; at 60%, LED1 & 2 solid, LED3 flashing.

According to TRM 8.1.6, the LED represents current SOC should be solid when BLINKMIDPT is disabled.

DISP is ok.

Thanks,

Zhihan

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105600 points

Hello Zhihan,

Are you able to verify this on an EVM? I currently don't have the ability to cycle batteries because we are still out of the lab from Covid.

Sincerely,

Wyatt Keller

0 Zhihan Zhang over 4 years ago in reply to Wyatt Keller

Expert 1100 points

Hi Wyatt Keller,

I actually found this behavior on one of my battery pack samples. And similar behavior occurs on my other battery packs as well.

Thanks,

Zhihan

0 Wyatt Keller over 4 years ago in reply to Zhihan Zhang

TI__Guru** 105600 points

Hello Zhihan,

Are you able to verify it on one of EVMs as well? It looks like this is expected behavior, when charging the LED that will be lit next will flash.

Sincerely,

Wyatt Keller

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BQ40Z50-R2: LED Display during Charging