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Original question:

BQ25792: About TDIE_ADC accuracy

BQ25792: About TDIE_ADC setting

Tsukui Yusuke
Guru 21930 points

Part Number: BQ25792

Hi,

Could you tell me more about past questions.
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1130790/bq25792-about-tdie_adc-accuracy/4197496?tisearch=e2e-quicksearch&keymatch=bq25792%20TDIE#4197496

>Therefore, the higher bit readings shifted higher to correct for the 12-bit setting issue.  A new datasheet revision just posted that states that the 12-bit setting is no longer recommended.

Customer want to measure TDIE before charging to avoid charging outside the temperature range.
As in the past post, the TDIE reading is lower than the outside temperature.

Please let me know the recommended usage of ADC_TDIE.
I want to improve the phenomenon that the temperature is detected low and measure the accurate DIE temperature.
And I would like to know the update information about DIE_ADC accuracy.

Best regards
Yusuke

  • +1
    TI__Guru**** 181076 points

    Hi Yusuke,

    To clarify, TDIE is the IC die temperature and is not related to the battery's safe temperature charge range.  The TS pin voltage, if connected to the battery thermistor with the proper resistor divider, is proportional to the battery temperature.    Also, the TDIE measurement itself is only accurate to +/- 10 C and then the 12-bit ADC error which skews it lower.  So, I recommend using the TS pin voltage to measure battery temperature and having host software convert it to a temperature as explained in the app note below:

    https://www.ti.com/lit/pdf/slua745

    I recommend using 13-bit or higher ADC measurement.    

    Regards,

    Jeff