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BQ34Z100-G1: Battery gauging for automotive applications

PRABHAT RANJAN TRIPATHI
Expert 1102 points
Part Number: BQ34Z100-G1

Hi TI experts,

I want to use BQ34Z100-G1 for gauging in a high current automotive application. The discharge current is in order of 100Amps, in the datasheet, it is mentioned that BQ34Z100-G1 utilizes a sense resistor for gauging.

However, for such high currents sense resistor will be very lossy and thermal management will be very tough. What does TI suggest for such a high current application? 

Is there any product for gauging in automotive applications?

  • 0
    TI__Guru** 105590 points

    Hello,

    We have a good application note about current scaling for higher current/voltages that are used in automotive applications. If you are only interested in large discharges you can reduce the sense resistor value and scale for the difference.

    Here is the application note: https://www.ti.com/lit/an/slua760/slua760.pdf?ts=1611078884573&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ34Z100-G1

    Sincerely,

    Wyatt Keller 

  • 0 in reply to Wyatt Keller
    Expert 1102 points

    Thanks for the application note. I get that the max differential voltage that can be applied to SRP and SRN pin is 125mV, but what about the resolution. 

    Say, I use a sense resistor of 0.1mili ohm, then will the gauge be in wake mode if the current drawn from the battery is less than 10 Amps because in that case differential voltage across SRP and SRN will be in the order of 0.1mV. 

    My concern is about resolution as well as discharge detection in the case of 0.1mV differential voltage.

  • 0 in reply to PRABHAT RANJAN TRIPATHI
    TI__Guru** 105590 points

    Hello,

    The resolution is based on how many bits, we have between 14-15 bits resolution (delta-sigma ADC) so the resolution is: 0.25V/(2^14) = 15uV (min)

    You'll just need to apply a high current for calibration to set the correct CC gain.

    Sincerely,

    Wyatt Keller