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BQ76952: BQ76952 for cell balance only

Cordell Reid
Prodigy 20 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQ76942

Hello, I wish to use a BQ76952 for balancing the cells of a12S battery pack composed of two 6S packs in series. I do not need any monitoring or circuit protection aside from balancing. If I want to use the internal fets, do I need to use any pins aside from the VC pins, Bat, Vss, and REG18? Would the following circuit suffice?

  • 0
    TI__Guru* 81034 points

    Hi Cordell,

    This is possible, but you will need to configure the BQ76952 registers for your application. For example, you will need to configure which cell inputs are connected in the VCell Mode register and you will need to configure the cell balancing registers to enable the cell balancing feature and to set the conditions when balancing should take place. You will also want to disable the charge pump to avoid additional current draw since CP1 is connected to BAT. Since you are not planning to use protections, you should disable all of the protections that are enabled in the default settings. I think you may need to add a thermistor because the balancing algorithm only allows balance within a safe temperature range. I think the PACK pin should be connected through a resistor to PACK+ - otherwise the default settings will trigger Shutdown based on an extremely low PACK voltage.

    You can configure the registers with a microcontroller in the pack or you can configure the registers on the production line and program the settings to OTP.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 20 points

    I would prefer to use a device that does not require any MCU or set up at any stage (No separate MCU). Since I am using two 6S packs in series, would I be able to make two separate boards using a device to balance each pack separately? I prefer to keep the board as minimal as possible also prefer to use the internal fets where possible to reduce size and part count. Are there any parts like that?

  • 0 in reply to Cordell Reid
    TI__Guru* 81034 points

    Hi Cordell, 

    This is the closest device we have to meet your specific need, but it does require configuring the settings. You could make two separate boards - I would suggest the BQ76942 (10S version of the device) if you only have 6 cells per pack. 

    Best regards,

    Matt