BQ40Z60: COT is triggered even though the temperature is below Tshutdown and it is also unable to recover after the COT recovery delay elapsed

Hello Hendra,

I don't believe the COT uses the FET temperature readout for the gauge, it uses the internal temperature. Also the OTC and COT protections are different and have different recovery methods.

Can you share the BQStudio log file showing the behavior along with the .gg file?

Sincerely,

Wyatt Keller

Hi Wyatt,

Sorry, I forgot to tell you that I enabled "TSint Mode" of the Temperature Mode, I think it will make the FET temperature value will be always the same as the Internal temperature. CMIIW

bat38.gg.csv

the gg.csv file is attached

Thanks

- Hendra

Hi Wyatt,

I believe that is COT not OTC,

Below is the captured Bit Register when the issue occurs :

Thanks for your help

- Hendra

Thanks Wyatt,

How about COT recovery, do you have an idea why the COT was not cleared after 5 seconds delay time ?

Thanks

- Hendra

Hello Hendra,

What I would suspect is the IC was still not cool enough to release the protection, if you cool the temperature much lower than the threshold does the COT ever clear or is it permanently set?

Sincerely,

Wyatt Keller

Hi Wyatt,

It was permanently set, the only way to clear the COT flag was by pressing the RESET command of BQstudio. 

I've reproduced the issue, I heated up the chip using a heater blower. When the internal temperature rose above 140 Degree-Celcius the COT is triggered. The COT flag was always in Red even though the temperature is already cooled down much lower than Tshutdown for more recovery delay time ( 5 s )

Thanks

- Hendra

Hello Hendra,

I will try to replicate the tests on our EVM, are you able to see the same behavior on multiple gauges or is it only one gauge?

Sincerely,

Wyatt Keller

Hi Wyatt,

I just replicated it with another gauge and I found the same behavior, the COT was permanently set.

Thanks

- Hendra

Hello Hendra,

Can you share your .gg file and .srec files to review? I would like to test with your exact settings as well as the default settings.

Can you also provide a SOP for exactly how you replicated it? What steps you took, was there a charge occurring for the replication or did you just heat the pat at idle?

Sincerely,

Wyatt Keller

Hi Wyatt,

In my testing, I left the charger adapter connected, I saw the charging current is detected, then I heat up the chip using a heater until the COT was triggered and I saw the charging current was down to 0. Once the COT was triggered, I moved away the heater from the chip, just it.

Below are the .gg.csv and the .srec ( note I use bq.fs file instead of srec file)

8054.bat38.gg.csv

srec file.zip

Thanks

- Hendra

Hello Hendra,

Thank you for the data, I will need to do some testing when I am back in office next week.

Sincerely,

Wyatt Keller

Hello Hendra,

Sorry for the delay, I have not had much time to go to the lab to try to re-create this.

Unfortunately I have not been able to replicate the issue you are seeing. I will continue trying to replicate, I believe it may have been an issue with my EVM. I will update if I find anything.

Sincerely,

Wyatt Keller

Hi Wyatt,

Thanks a lot, I really appreciate all of your efforts

Thanks

- Hendra