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BQ76952: Display when charging and when discharging

oh changhyun
Prodigy 20 points
Part Number: BQ76952

Tool/software:

Is it possible to operate each led using gpo pin when charging and discharging?

Desired operation

charging = charging led on, discharging led off

discharging = charging led off, discharging led on

  • 0
    TI__Expert 4245 points

    Hello ChangHyun,

    Yes, depending on how you set it up.

    It is actually better to read the current measurements and have the MCU control the AFE's GPOs to indicate whether it's charging or discharging OR have your MCU control the LEDs with its own GPIOs. 

    Table 6-5. Multifunction Pin Options for ALT or GPO Pins in the BQ76952 Technical Reference Manual indicates which bits can be used as GPO pins for our device.


    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 20 points

    Thank you for your answer.

    I tried to do it with DCHG and DDSG pins, but I failed.

    It seems to work only for errors.

    ALERT, CFETOFF, EFETOFF, TS1,TS2, TS3, HDQ, DCHG, and DDSG

    What pins should I use to operate led without mcu?

    If it doesn't work with those pins

    Then, how can I configure the circuit to operate the LED without the MCU?

  • 0 in reply to oh changhyun
    TI__Expert 4245 points

    Hello ChangHyun,

    I apologize for the confusion caused by my previous statement there as I realized my mistake.

    After confirming with my team, there is not a good way to configure the LED without an MCU to check the current measurement values, as that is the best way to indicate if the device is charging or not.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 20 points

    Ok. I understand. 

    so Isn't LED connection for error check also a good way?

    When the battery is charging and discharging, connecting the LEDs to the DDSG and DCHG pins for error checks causes problems with the board. What's the problem?

    (DCHG Pin Config 0xb2, DDSG Pin Config 0xb2 , reg1 = 3.3v) It's set up like this.

    It's a circuit diagram.

  • 0 in reply to oh changhyun
    TI__Expert 4245 points

    Hello Changhyun,

    By default, both the DSG and CHG FETs should be on which makes it difficult to tell if the device is actually charging or discharging. This is also not the desired operation you described above with the LEDs.

    Section 6.7 DDSG and DCHG Pin Operation of the BQ76952 Technical Reference Manual gives more information regarding them. 

    When you say that the LEDs connected to DDSG and DCHG pins for error checks are causing problems with the board, what kind of problems do you mean?

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 20 points

    There is no problem when the LED is connected to one of the DDSG pins or DCHG pins, but the board did not work when it was connected together at the same time.

    Then, when checking the charging and discharging using the MCU, does it operate using the CC2 current value?

  • +1 in reply to oh changhyun
    TI__Mastermind 19210 points

    Hi Changhyun,

    In what way does the board not work? Are you using the REG18 output drive or the REG1 output drive? If you are using REG18, it could be that you are pulling too much current from REG18. REG18 is meant to power the internal circuitry and cannot support very much current draw. If the LEDs are drawing too much current from the LDO and causing the voltage to drop, then the device could power off entirely.

    For checking whether the device is seeing charging current or discharging current, the MCU can use any of the CC registers, but CC2 will update the most often.

    Regards,

    Max Verboncoeur