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BQ25601: JEITA Profile of temperature monitor

Fan Wu
Intellectual 705 points
Part Number: BQ25601

Hi Sir/Madam,

I am evaluating BQ25601 and want to implement it in our product. However I am a bit confused about 8.3.7.5 JEITA Guideline Compliance During Charging Mode (page 21 of datasheet).

1. It only mentioned a profile which stop charging when temperature is below 0 degree or above 60 degree. Can we customize this limitation? our battery cell can only be charged between 0 to 45 degree.

2. In page 21, it has two Equations and values of RTHcold/RTHhot/RT1/RT2. I assume these values are the results of the two equations. But when I put these values in the equations, they does not work. Did I put the wrong value? My calculation is as below

RT2= [4.7*27.28*3.02*(1/4.2-1/4.1)]/[3.02*(4.7/4.1-1)-27.28*(4.7/4.2-1)}=0.822. However, in the datasheet, RT2=30.9K

RT1=(4.7/4.2-1)/(1/30.9+1/27.28)=1.72. However, in the datasheet, RT1=5.23K

Thanks!

cheers

Fan

  • 0
    TI__Genius 16185 points

    Fan,

    I think due to BQ25601 has Jeita thermal specification, so maybe meet your Cold and Hot temperature requirement.

    And I also attached one BQ2419x RT1 and RT2 calculation tool for your reference, you can use this excel file to calculate RT1 and RT2 value.

    And please use below parameter to exchange data. This tool should be helpful for you to reduce calculation effort.

    Thanks

    Vvref=Vregn
    VLTF=VT1
    VTCO=VT5

    bq24192i TS setting.xlsx

  • 0 in reply to Paul Yeh
    Intellectual 705 points

    Hi Paul,

    Thanks for your reply. Very appreciated.

    If I use VT5 as VTCO in the calculation, it means when temperature exceeds T5, charging will be suspended, right?

    And according to datasheet of BQ25601, when temperature is between T3 and T5, Vreg will be set to 4.1V if JEITA_VSET=0, correct? 

    The default value of JEITA_VSET is 0. It means before host side access in and change the register value, if battery voltage is higher than 4.1V, charging will be stop, right?

  • 0 in reply to Fan Wu
    TI__Genius 16185 points
    Fan,
    1. If TS>T5 then charger will suspended
    2. If Jeita_Vset=0 then Vreg will change to 4.1V DURING T3~T5 range
    3. Yes, you are right. Due to charger will be battery OV.
    Thanks
  • 0 in reply to Paul Yeh
    Intellectual 705 points

    Hi Paul,

    Is the temperature value on TS pin of BQ25601 readable from Host via I2C bus?

    I did not find the register in the datasheet.

    If it is not readable, does that mean I need another temperature sensor to monitor battery temperature when battery is discharging?

    Thanks!

    cheers

    Fan

  • 0 in reply to Fan Wu
    TI__Mastermind 25800 points
    Hey Fan,

    The exact temperature value will not be reported in a register from the BQ25601. However, the charger will inform you of the Temperature Window it is actively in, such as TWARM, TCOOL, THOT, TCOLD, or TNORMAL.


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    Intellectual 705 points
    Hi Joel,
    OK. Thanks!