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Power management forum

hojin yoo
Prodigy 50 points
Part Number: BQ21080
Other Parts Discussed in Thread: BQ25180,

Tool/software:

Hello all.

We use bq21080 chip and test board(EVM) is bq25180. 

 The photo above shows our setting. and ICHG is 500mA and ITERM is 10% of ICHG.

We placed it in a 45°C chamber and started charging. Initially, it charged at 500mA, but the charging stopped when the internal temperature of the set reached 48°C.

NTC setting were also carried out according to the guide. 

When I think about it, the charging should be at 100mA in the 45°C range, but it’s not operating that way. What could be wrong?

Thank you. 

  • 0
    TI__Expert 8315 points

    Hello Hojin,

    Could you please provide the register settings when the device stops charging? 

    BQ21080 has thermal protection (TSHUT) and thermal regulation (THERMREG) features to protect the IC from damage due to overheating (refer to page 19 of the BQ21080 datasheet). If the IC is in thermal regulation (Reg0x00 bit 1 = "1"), then it's possible that the charge current is being reduced significantly.

    hojin yoo said:
    When I think about it, the charging should be at 100mA in the 45°C range, but it’s not operating that way. What could be wrong?

    The TS settings are related to battery temperature. On the BQ25180 EVM, a potentiometer can be adjusted to achieve different VTS values, simulating different battery temperatures. For more information about the TS function, please refer to page 22 of the BQ21080 datasheet.

    Best regards,

    Alec Lehman

  • 0 in reply to Alec Lehman
    Prodigy 50 points

    Hi Alec Lehman

    Here is the register settings. Please check if this value is related to the charging stopping. 

    bq21080_set_input_current_limit() + current_limit[1100]
    bq21080_set_precharge_current() + pre_charge_current[0]
    bq21080_set_charge_current_limit() + charge_current_limit[500]
    bq21080_set_battery_voltage_limit() + battery_voltage[4200]
    bq21080_set_termination_current() + termination_current[10]
    bq21080_dump_all_register() reg_value[0x00] = 0x61
    bq21080_dump_all_register() reg_value[0x01] = 0x00
    bq21080_dump_all_register() reg_value[0x02] = 0x00
    bq21080_dump_all_register() reg_value[0x03] = 0x46
    bq21080_dump_all_register() reg_value[0x04] = 0x4D
    bq21080_dump_all_register() reg_value[0x05] = 0x6C
    bq21080_dump_all_register() reg_value[0x06] = 0xD3
    bq21080_dump_all_register() reg_value[0x07] = 0x8B
    bq21080_dump_all_register() reg_value[0x08] = 0x4F
    bq21080_dump_all_register() reg_value[0x09] = 0x00
    bq21080_dump_all_register() reg_value[0x0A] = 0x41
    bq21080_dump_all_register() reg_value[0x0B] = 0xA2
    bq21080_dump_all_register() reg_value[0x0C] = 0xC0

    and I will check TSHUT and THERMREG that you mentioned. 

    Best regards,

    Hojin yoo

  • 0 in reply to hojin yoo
    TI__Expert 8315 points

    Hello Hojin,

    Thank you for providing the register settings. It seems that charge was terminated, as CHG_STAT is reporting "Charge Done or charging is disabled by the host."

    Could you please measure the voltage on the BAT pin?  Are you using a real battery cell or a battery simulator/e-load?

    Best regards,

    Alec Lehman