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BQ35100: Supply voltage and flash writes

Part Number: BQ35100

Hello,

I plan to use the BQ35100 in a system, which is powered by a 3V CR2 battery (Lithium Manganese Dioxide (LiMnO2) chemistry).
The system is designed to run with a voltage down to 2.5V, while the battery is discharging.

The datasheet of the BQ35100 states two supply voltage ranges. One from 2.7V to 4.5V with "No operating restrictions" and 2.45V to 2.7V with "No FLASH writes".

As I understand the reference manual correctly, flash writes are necessary for calibration, Accumulator mode and End-Of-Service (EOS) mode.
Calibration will be done one time for the system with a full battery at 3V.
Because of the used battery, the BQ35100 will run in the STATE-OF-HEALTH (SOH) mode.

So my questions are:

  1. Can I use the BQ35100 the with the 3V CR2 battery down to 2.5V in SOH mode?
  2. The system has a dynamic current consumption of 10µA (most of the time),  5mA (for 100ms), 100mA (for 200ms) and 400mA (for 30ms), can the BQ35100 handle this range?

with kind regards

  • 1. Yes. The will be barely any need for DF writes.
    2. The gauge in SOH mode does not use the current measurement, so you need to ensure that you are in a relaxed mode when the gauge takes measurements. The gauge estimates SOC based off DOD which is a function of (OCV and temperature). That being said the gauge will be able to function with your current profile as long as you take measurements in rest.
    thanks
    Onyx
  • Hi SST,

    When Voltage is below the Flash Update OK Voltage, flash writes are disabled to prevent corruption to dataflash (if the flash were to enter a brownout state).

    The device should be operated between 2.7 and 4.5 V. The device may not operate properly below 2.7 V.

    The bq35100 will readily operate in the range of 5 mA to 400 mA. The 10 uA drain is on the order of the lowest current consumption of the device and should not affect device gauging performance.

    Sincerely,
    Bryan Kahler
  • In reply to Bryan Kahler:

    Hi Bryan, hi Onyx,

    thank you for your replies.

    Can one of you give me a distinct 'yes' or 'no' for the voltage range 2.5V to 3V in SOH mode?

    with best regards

  • In reply to SST:

    yes

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