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BQ79616-Q1: Solution using external balancing transistors

Pavel Velikov
Prodigy 20 points
Part Number: BQ79616-Q1

Tool/software:

Is there anyone who successfully implemented external balancing Mosfets?

There are only 2 occasions where this topic was discussed 3 and 4 years ago but seems no real solution succeeded.

I am afraid that the the internal Mosfets are going to be extremely hot, and even the device cuts balancing from time to time, there would be 105 degrees on its body all the time.

  • 0
    TI__Expert 6720 points

    Pavel,

    I am not aware of anyone who has explicitly used external balancing Mosfets. The internal Mosfets do get hot, but the device will function normally with up to 240 mA of balancing current at an ambient temperature of 75 degrees C (As per section 9.3.3.1.3 of the datasheet). If you require a specific temperature limit there are built in temperature sensors that will pause balancing when the temperature goes above the user-set threshold.

    Regards,

    Bo 

  • 0 in reply to Benjamin Luty
    Prodigy 20 points

    Bo, I was hoping for solution ...
    But this sounds familiar ... yeah ...:

    -----------------------------------------------------
    The Fox & the Grapes (Aesop's fable)

    A Fox one day spied a beautiful bunch of ripe grapes hanging from a vine trained along the branches of a tree. The grapes seemed ready to burst with juice, and the Fox's mouth watered as he gazed longingly at them.

    The bunch hung from a high branch, and the Fox had to jump for it. The first time he jumped he missed it by a long way. So he walked off a short distance and took a running leap at it, only to fall short once more. Again and again he tried, but in vain.

    Now he sat down and looked at the grapes in disgust.

    "What a fool I am," he said. "Here I am wearing myself out to get a bunch of sour grapes that are not worth gaping for."

    And off he walked very, very scornfully.
    ------------------------------------------------------

    I've read the datasheet - as low you set your desired temperature, as longer the device will need to cool down ... practically it will cool down 90% of the time ... unfortunately we have no such time to wait for.
    Temperatures of 105 (or even 75 degreees) are not recommended when designing high reliability circuits. Our company does that and this is the reason I am looking for a real solution. I have one - working well (using TI competitor's xxx681x device), so maybe I will need to stuck with it even our safety approval will be more difficult using their documentation.

    Regards,

    Pavel