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BQ27531-G1: Does BQ27531-G1 automatically disable BQ24193 to charge in low or high temperature?

K.Yaita
Guru 29720 points
Part Number: BQ27531-G1
Other Parts Discussed in Thread: BQ24193

Hi Team,

My customer is evaluating their board that BQ27531-G1 and BQ24193 are mounted.
I would like to ask about Temperature Charging of BQ27531-G1.
BQ27531-G1 TRM shows the following.



If my customer set as Table 3-15 and then temperature goes less than 0℃ or more than 60℃, does BQ27531-G1 automatically disable BQ24193 to charge?
My customer has not confirmed the function yet, there is no I2C communication between BQ27531-G1 and BQ24193 although temperature is changed.
The battery temperature can be read normally by BQ27531-G1 so I believe the connection of thermistor is no ploblem.

If you need my customer's schematic please send me private message then I can share the schematic.
Your support would be appreciated.

Best Regards,
Yaita

  • 0
    TI__Guru** 105760 points

    Hello Yaita,

    If the gauge and charger are communicating then it will follow the specifications on the gauge TRM, if they aren't communicating you would need to contact the chargers team if it's being used as a stand alone charger.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your reply.
    My customer expects BQ27531-G1 to control BQ24193.
    Is there any commands that is required for BQ27531-G1 (gauge) communicates to BQ24193 (charger) ?

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    Can you share a schematic of how they ae connecting the two? I'm trying to understand how they're being used. They're designed to communicate with each other, in your first post you mentioned they aren't communicating. Are the two connected but the two aren't communicating?

    Also make sure the gauge is enabled to control the charger in the gauge TRM: 2.1.24 GG_CHGRCTL_ENABLE: 0x001C

    Check the config for the charger in the gauge TRM: 3.3 Data Flash Settings for Charger Operation

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your kind support. I will check your advice.
    Let me contact again if we need your further support.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Guru 29720 points

    Hi Wyatt-san,

    Thanks to your advice, my customer can confirmed the operation of Temperature Charging.

    I would like to ask an additional question.
    Regarding Table 3-15, it shows the unit of Charge_Current_Tx is based on Design Capacity.
    Is it true?

    My customer said AverageCurrent() shows about 800mA although he set Design Capacity=1100[mAh] and Charge_Current_Tx=50[%].
    Is it possible case? I think expected AverageCurrent() is about 550mA, so would like to confirm just in case.

    I also heard CalcChargingCurrent() and ProgChargingCurrent() shows 1024[mA] in this case.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    Yes it should be based on the design capacity, the CalcChargingCurrent() is what the gauge wants to charge at, so something with the battery/charging is not allowing the max charge current.

    Can you share a log and .gg file of the test so we can take a look?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your kind support.
    I attached log and .gg file.
    *The log is captured when charging the battery.

    Please let me know if you need additional information.

    Best Regards,
    Yaita
    BQ27531.gg.csv
    7558.charge.log

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    I will take a look sometime this week or early next week, the storms in Texas have taken out the power.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your kind reply.
    I'm sorry to hear that, I understand the situation. I will wait for your feedback.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    It looks like the charger is in the constant voltage phase, the current is can change dynamically as the temperature changes (which it looks like it's doing from the logs)

    Every time the taper changes the current also changes, if it was in the CC region I would expect it to be what your customer is expecting.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your reply.
    Do you know why AvgCurrent goes up to 800mA with the setting of BQ27531.gg.csv?

    Is it unexpected behavior for my customer and he wants to decrease the charging current.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    I took a look through again, it does look like the charging current reported should be less. I noticed in the charger configuration the DEFAULT_OVRD is set, which may not let the gauge control the charger, it will charge according to the chargers memory not the gauge.

    If the charge current doesn't change when they edit the gauge data flash then it is most likely blocked by this bit.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your continuous support.
    I suggested DEFAULT_OVRD=0, however the result looks like the same.
    Could you look into attached log and gg file?

    27531_20210224.gg.csv
    27531_20210224.log

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    When they change the range in the gauge does it also change the charge current?

    I'd like to isolate if the issue is the gauges information isn't being received by the charger because of some configuration of the charger/gauge or if the values aren't updating the charging current correctly.

    What is the chargers default configuration? Does it match what is occurring during their charge?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    >When they change the range in the gauge does it also change the charge current?
    Yes, if my customer change Charge_Current_Tx=80% (Design Capacity=1100mAh) then he saw AvgCurrent goes up to about 1000mA.
    He also confirmed charge current (AvgCurrent) changed with increasing / decreasing temperature as expected.
    The configuration of BQ24193 is controlled by BQ27531-G1. There is no direct access to BQ24193.

    What he doesn't understand is the unit of Charge_Current_Tx is not based on Design Capacity. 

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    The percentage should be based on the design capacity, it looks like based on the examples given it's only applying the percentage to half the design capacity. You can try using the DIV_CUR_ENABLE to reduce the current further.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    I have my customer try using DIV_CUR_ENABLE then I will update this thread.

    My customer can adjust Charge_Current_Tx according to the actual charging current, but he wants to know if it is a possible case that AvgCurrent goes more than "Design Capacity x Charge_Current_Tx [%]" and the correct way to set charging current if it's possible.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    It looks like the charge current percent is only applied to half the design capacity, I believe by setting the DIR_CURR_ENABLE the full range can be used.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    AverageCurrent changed from 857mA to 480mA as the following when my customer sent DIV_CUR_ENABLE.
    I think it operated the same as Technical Reference Manual refers.
    ----------------------------
    2.1.19 DIV_CUR_ENABLE: 0x0017
    The host can send this command so that the charging current is reduced to half of what is in CalcChargingCurrent().
    ----------------------------






    >It looks like the charge current percent is only applied to half the design capacity
    I can't catch what you referred definitely. Did you refer following red line is likely to be "Design Capacity x 2"?



    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    I can check why it doesn't seem to follow the TRM, the current it seems to be applying from the data points you have given is:

    charge current = ((% of C rate)/2)*C

    So if the set the DIV_CURR_ENABLE it should set the value they need, they will just need to adjust the values in the DF.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    >charge current = ((% of C rate)/2)*C
    Is the calculation formula true?
    Regarding log and gg files, AvgCurrent shows ~900mA when Design Capacity = 1100 [mAh], Charge_Current_T = 50 [%].

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    Sorry I had sent the wrong formula, this is what I meant to send:

    ChargeCurrent = 0.5*C(1+(% of C rate))

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Thank you for your continuous support.

    >I can check why it doesn't seem to follow the TRM, the current it seems to be applying from the data points you have given is:
    Could you check why it doesn't seem to follow the TRM? It is my customer's main concern.
    It is helpful for us if we confirmed the formula is what it is supposed to be. 

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    Yes I will put an internal ticket in to verify the correct formula is used. This may take some time to hear back from the other teams.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    I appreciate your continuous support.
    OK. I will wait for the team's feedback.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Guru 29720 points

    Hi Wyatt-san,

    Is there any update?
    Is it required to need some days?

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita-san,

    Please try setting the 3.1.4 Chrgr_Current_Reg2(): 0x77 to 0x00, I believe the offset is causing the issue you're seeing.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    It seems Chrgr_Current_Reg2() is a command that only returns the current control register of the charger (BQ24193). 
    My customer doesn't access the registers of BQ24193 directly but do you refer he should access BQ24193 register directly at the begininng?



    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Guru 29720 points

    If the answer is yes, I understand he should change the following register of BQ24193.
    However, I have doubt if the value of the register relates to the issue..



    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Guru** 105760 points

    Hello Yaita,

    Sorry for the late responses, I will discuss further with the chargers team on Monday and give you an update.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Guru 29720 points

    Hi Wyatt-san,

    Is there any update?

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Guru 29720 points

    Is there any update?

    Best Regards,
    Yaita