• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 380 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

Resolution of BQ34Z100-G1

BQ34Z100-G1: Resolution of BQ34Z100-G1

Yusuke Mukuno
Expert 7395 points
Part Number: BQ34Z100-G1

Hi

This E2E post is related to the past one.

Customer want to use 2mohm sense resistor for Imax=30A/ Sense resolution min=1mA.

Is it possible?

Also, Could you please let me know about your recommendation for deadband setting.

Muk

  • 0
    TI__Guru* 81034 points

    Hi Muk,

    To get the best resolution, they should select the sense resistor to maximize the input range of the ADC (+/-125mV). Using only a portion of the range will reduce the resolution. For this case, I would suggest using 4mohm.

    For deadband setting, it really depends on the application - will it be running at low currents for a large percentage of the time? For a 30A application, I would normally suggest setting the deadband to 10mA, but there are many things to consider. I am attaching a document that discusses the sense resistor and deadband selection process in more detail.

    /cfs-file/__key/communityserver-discussions-components-files/196/Sense-Resistor-Selection-for-Optimum-Battery-Gauge-Performance-_2D00_-3.pdf

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    TI__Expert 7395 points
    Hi Matt,
    Thank you for your answer. I appreciate your quickly support!

    Muk
  • 0 in reply to Yusuke Mukuno
    TI__Expert 7395 points

    Hi Matt,

    Customer have additional question.

    Does 4mohm resistor have really no problem? They have the concern from the description in datasheet as below,

    (Datasheet P29, 7.3.5 Fuel Gauging)

    The bq34z100-G1 measures the cell voltage, temperature, and current to determine the battery SOC based in
    the Impedance Track algorithm (refer to Theory and Implementation of Impedance Track Battery Fuel-Gauging
    Algorithm Application Report [SLUA450] for more information). The bq34z100-G1 monitors charge and discharge
    activity by sensing the voltage across a small-value resistor (5 mΩ to 20 mΩ typ.) between the SRP and SRN
    pins and in-series with the cell. By integrating charge passing through the battery, the cell’s SOC is adjusted
    during battery charge or discharge.

    Thanks

    Muk

  • 0 in reply to Yusuke Mukuno
    TI__Guru* 81034 points
    Hi Muk,

    A 4 mOhm sense resistor is okay. I think this comment in the datasheet is a common point of confusion, so I will look into getting this updated to clarify. For a 30A application, 4 mOhm is a good value.

    Best regards,
    Matt