BQ27425-G2A: Chip ready question

AJ Cheng

Part Number: BQ27425-G2A

Hello.

BQ27425-G2A CE pin is connected to the system GPIO and chip disable after system shutdown, will it affect the accuracy of Fuel Gauge?

BQ27425 How long does it take to wake up from shutdown?

Which Flag or Bit will be lifted to indicate voltage and capacity calculation are ready?

Thanks for kindly help~

over 7 years ago

0 Onyx Ahiakwo over 7 years ago

TI__Guru* 76230 points

Hi AJ
There is an init flag that gets set indicating the gauge's calculations are done and the values reported by the gauge are valid.
It takes about 2 sec for the init flag to get set after wake up from shut down so to have some margin 2.5 s is a good no to wait before reading values from the gauge.

Given that this chip does not have flash, whenever the devices shutdown, the data memory values stored in non- volatile memory of the host should be reloaded on the gauge for it to resume accuracy.

thanks
Onyx

0 AJ Cheng over 7 years ago in reply to Onyx Ahiakwo

Genius 3615 points

Dear Onyx.
Good day.
Can I check “QMAX_UP” and “RES_UP” flag ? It better to confirm the initialization success ? Thanks for help~

0 Onyx Ahiakwo over 7 years ago in reply to AJ Cheng

TI__Guru* 76230 points

qmax and res_up are flags indicating qmax has learned and resistance updates has occurred. Those are different from the INIT flag which shows that the gauges initialization process is complete after wake from shut down mode.
thanks
Onyx

0 AJ Cheng over 7 years ago in reply to Onyx Ahiakwo

Genius 3615 points

Dear Onyx
Do you suggest is to check “BAT_DET flag” to confirm bq27425 initial finish ? Thanks for kindly help~

0 Onyx Ahiakwo over 7 years ago in reply to AJ Cheng

TI__Guru* 76230 points

No. Initialisation is different from learning completed. There is the init flag which lets you know the gauge is done initializing from power up.
For learning, the qmax and resup flags will let you know learning is complete
thanks
Onyx

0 AJ Cheng over 7 years ago in reply to Onyx Ahiakwo

Genius 3615 points

Dear Onyx.
Good day.
Can you help to find out where is the “init flag” from bq27425 datasheet?
I can’t find out it. Thanks for kindly help~

0 Onyx Ahiakwo over 7 years ago in reply to AJ Cheng

TI__Guru* 76230 points

Hi Aj,

I am sorry i was wrong. This chip is a little different from our other gauges in that it does not have the INIT flag. However, after insertion of your battery and the BIE is set, you need to wait for 3s for initialization to complete.

thanks
Onyx

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BQ27425-G2A: Chip ready question