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Original question:

BQ24105-Q1: How to use BQ24105-Q1 for NiMH charging without using an external MCU

BQ24105-Q1: How to stop charging without MCU

Koji Hayashi92
Mastermind 7030 points
Part Number: BQ24105-Q1

Hi TI-team

If I do not use an external MCU, can I stop charging halfway when fully charged much earlier than the Safety timer time?

My customer is concerned about overcharging.

After all, is it easier to use an external MCU because it requires ADC and logic ?

 

Best Regards,

Koji Hayashi

  • 0
    TI__Guru**** 165766 points

    Hi Hayashi-san,

    I can think of a few of ways to use hardware to force early termination. 

    1. Use a FET +series resistor in parallel with bottom FB resistor to alter the regulation threshold.  When the MCU is attached, one of its GPIO can control the FET to increase the battery regulation voltage.

    2. Use a FET + series resistor in parallel with ISET2 to set a lower ITERM current when MCU is attached.

    3. Use a comparator to compare VTSB to BAT voltage and pull /CE high.  You would have to use the MCU GPIO to alter this when it is attached.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Mastermind 7030 points

    Hi Jeff-san

    Thank you for quick response.

    Does every setting require an MCU ?

     

    Best Regards,

    Koji Hayashi

  • 0 in reply to Koji Hayashi92
    TI__Guru**** 165766 points

    Hi Hayashi-san,

    Your customer can add an external comparator, with VTSB as reference, to monitor the charge voltage and then drive /CE high or one of the FETs from items 1 and 2 above.  Then when the MCU is attached, the comparator can be disabled.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Mastermind 7030 points

    Hi Jeff-san

    Thank you for response.

    I understand.

    Best Regards,

    Koji Hayashi