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Original question:

BQ35100: EOS for BQ35100

BQ35100: bq35100 minimal current sensing

Foulques de Varine
Prodigy 20 points
Part Number: BQ35100
Other Parts Discussed in Thread: TIDA-01546

Hello,

I'm interested in monitoring the consumption of an application powered by a primary battery Li-SoCl2 (Very flat discharge). The application a want to monitor has a consumption of few micro amps 99% of the time.

The bq35100 seems like a perfect fit because of the EOS mode. In this mode the bq35100 measures the temperature, voltage and the current to determine the resitance of the battery.

My question is " is the Bq35100 has a sensitivity for this type of current (below 10 to 20µA), or do I need like in the evaluation board TIDA-01546 (using Bq35100) an amplifier with an ADC to see any increese of the current consumption ?"

I hope I've been clear.
Thank you in advanced.

Foulques

  • 0
    TI__Guru* 76230 points
    Hi Foulques

    What is the capacity of the battery? Your load has to be significant enough for the voltage to see a dip for the device to be able to calculate resistance.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 20 points

    Hi Onyx

    Thanks for the quick answer. 

    The battery we are currently using is an LS17500. The capacity of it is 3.6Ah. 
    If the current sense resistor between SRN and SRP is large enought (I Ohm) , the bq35100 will be able to measure the current and so the variation of the battery resistance ?

    Also, on the technical reference manual in 11.9 Current(), it's written that the current flowing into the current sense resistor has a resolution of 1mA per bit.
    "Current(): 0x0C/0x0D This read-only command pair returns a signed integer value that is the average current flowing through the sense resistor. It is updated every 1 second with units of 1 mA per bit."




    Thanks 
    Foulques

  • 0 in reply to Foulques de Varine
    TI__Guru* 76230 points
    Hi Foulques

    The delta voltage under High Pulse Load must be ≥ 100mV for the EOS algorithm to work.

    thanks
    Onyx