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BQ79656-Q1: Battery monitor selection help.

Part Number: BQ79656-Q1
Other Parts Discussed in Thread: BQ76930, BQ76PL455A

Hello,

I am looking for a basic battery monitor, but am not sure which is my best option. Can you help point me to some that might work well? I have a few questions and requirements.

  1. We have a high current and small size application 100A+ that makes current sensing and in line FETs not feasible. For battery monitors with those items in the reference designs (Ex: BQ76930), do they require shunt resistors and in line FETs, or are they only optional?

 

Requirements:

Must have

  1. 7 Lipo cells. Ability for future expansion is nice.
  2. 85C+ rating
  3. Low/no power mode for storage.
  4. In stock.

Nice to have (Listed in priority)

  1. Internal cell balancing.
  2. Small design footprint.
  3. Reference designs with BOM
  4. Auto or better rating.
  5. External. Temperature sensing.
  6. Design files/gerbers available.

Thank you,

Cameron

  • Hi Cameron,

    For auto rated devices, I recommend reviewing datasheets for bq76pl455a (16 channel), bq79606a (6 channel) and bq79616 (16 channel) in order of release date. They all should meet most of your requirements and usually require an external shunt resistor for current sensing. The bq79656 device you reference has two pins to do a current sense measurement to avoid external INA device but you'll still need the shunt resistor.

    Regards,

    Taylor

  • Hello,

    Thank you for the information.  Can you point me to any battery monitor chips that do not require a current sense resistor to operate? What would happen if I had a 0 ohm resistor connected? I do not need a current measurement and am mainly just looking to monitor voltages. Cell balancing would also be nice.

  • Hi Cameron,

    If you don't need a current measurement then you don't need anything extra to add for the devices to operate. All 3 devices I listed above do not support current sensing by default so additional components would be needed if you want the feature. They all support voltages and cell balancing as well. But whereas the bq76pl455a requires external FETs to balance, the bq79606a and bq79616 family has integrated FETs for roughly 200mA of passive balancing current.

    Regards,

    Taylor

  • Thank you. I misunderstood your first reply. I will look into those other devices.

  • Hello again,

    All three of those devices are either very low or out of stock. Do you know of any devices that are in stock will still function without current sensing? An auto rating is nice, but not required.

    Do you know when stock will be available for those devices?

    Thank you

  • Cameron,

    This is a technical forum so I don't have further insight onto the stock situation. As you know the chip industry at large is experiencing supply constraints. If you need further info I would need to recommend you to your local TI sales representative.

    Regards,

    Taylor