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BQ25792: Increasing the charging current

Bharath Kumar
Prodigy 30 points
Part Number: BQ25792
Other Parts Discussed in Thread: BQSTUDIO, USB2ANY, , EV2400

Hi,

Good Day!!

we are using BQ25792 for charging the battery, for the 4s cell battery currently its charging at 1A as mentioned but we need to increase the charging current by 2.5A or 3A will it be possible with the 4s cell without any software support. 

we are not using PD controller. direct 16V from the adapter.

Can you give some suggestion to increase the charging current to 2.5A or 3A...?

Thanks,

Bharath Kumar

  • 0
    TI__Guru**** 169466 points

    Hi Bharath,

    Unfortunately, the charge current can only be increased by using the I2C host to write to the I2C register.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 30 points

    Hi,

    Thanks for the reply, we are trying to write the data on the register (3h REG03_Charge_Current_Limit Charge Current Limit Section 9.5.1.3 ). we can able to read the data from the register which is 64 is equal to 1A. we want to change it to 2A but we couldnt able to write on the register.

    We are using AARDVARK- Total phase tool for writing and reading the register. 

  • 0 in reply to Bharath Kumar
    Prodigy 30 points

    Hi,

    when we try to write data on the other offset reg we can able to read & write but only on the particular offset reg 3h we could not able to write data. can you help why we are not able to write data on the particular reg.

    Below is image of total phase tool for reference.

     

  • 0 in reply to Bharath Kumar
    TI__Guru**** 169466 points

    Hi Bharath,

    There is no reason I can think of that total phase should not be able to write to that register.  That register resets to default after WD timer expires but default expiration time is 40s. Can you look at the SCL and SDA lines on an oscope and confirm that are clean pulses?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 30 points

    Hello Jeff,

    we have checked probing the I2c lines its proper.

    Same i2c lines are used to write the data on the other offset reg but its working fine. So I don't think there is an issue with the i2c lines.

     

    Regards,

    Bharath

  • 0 in reply to Bharath Kumar
    TI__Guru**** 169466 points

    Hi Bharath,

    That is strange.  No other customer has seen this issue.  Is this on BQ25792EVM or your own board?  If EVM, can you use EV2400 communication box and BQSTUDIO software or USB2ANY and TI CHARGER GUI to write to that register?

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 30 points

    Dear Jeff,

    we are using it on our own board. but the tool is working fine since i can able to read and write on the other offset register of the BQ25792?

    regards,

    Bharath 

  • 0 in reply to Bharath Kumar
    TI__Guru**** 169466 points

    Hi Bharath,

    If you can read/write the other 16 bit register, this one should not be different.  We have not had any other customers have this issue?  Does this occur on multiple ICs?  If you connect your tool to the BQ25792EVM, can you change the EVM IC's charge current?  

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 30 points

    Dear Jeff,

    As i told we dont have EVM we are using it on our own design. I can able to read and write other 16bit register, we tired on multiple IC. But, result is same we could not write on the particular register.

    we can able to write, after if we read its changing to default value.

  • 0 in reply to Bharath Kumar
    TI__Guru**** 169466 points

    Hi Bharath,

    Unfortunately, I do not have a suggestion.  If your tool can write to the other 16-bit registers, there is no reason why it should not write to the charge current register.  The only time that register (and many others) gets reset to default is at POR or when the WD timer expires or if the REG_RST bit is written.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 30 points

    Hi Jeff,

    Is there any sequence to be followed before writing on the particular offset register 3h?

    so whats next?

    regards,

    Bharath 

  • 0 in reply to Bharath Kumar
    TI__Guru**** 169466 points

    Hi Bharath,

    There is no sequence.  If your I2C tool can write to the other 16 bit registers with no issue, there is no reason your I2C tool should not be able to write to the charge current.   Please try a different tool.

    Regards,

    Jeff 

  • 0 in reply to Jeff F
    Prodigy 30 points

    Dear Jeff,

    we tired with different tool as well, but we could not be able to write the reg also we came to know that Input current limit register also we couldn't be able to write. So, I doubt 16-bit register having writing issue. could you please provide your suggestion.

    For your reference I have attached the schematics image for your reference, please verify the below circuit diagram as well is this correct or needs to be changed.

    Battery charging at 1A is working fine with the below circuit, but we need it for 2.5A or 3A. 

    Thanks & Regards,

    Bharath Kumar D

  • 0 in reply to Bharath Kumar
    TI__Guru**** 169466 points

    HI Bharath,

    REGN needs a capacitor.  4.7uF >=10V is recommended.

    Certain registers, like charge current, reset to default values if the WD timer expires.  I assume you have WD disabled or you are periodically writing to the WD bit.  If so, then your tool should be able to write to charge current register.  There is no other limitation on writing to that register.

    The input current limit register is clamped to the value set by ILIM_HIZ resistors if the EN_ILIM bit = 1.  Your resistors appear to have input current limit clamped to 313mA?  The maximum input current limit register setting is 3.3A. To set ILIM_HIZ to the max, you can connect it directly to REGN.  On your schematic, you can change R120 to 0 ohm and R121 to a 4.7V capacitor.

    Regards,

    Jeff