BQ34Z100-G1: Biased voltage calibration

Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO, BQ34Z100

Hi team,

The BAT intersection of the IC is 900 mV based on 28.4 V registration. Voltage divide is 28.4 V before calibration and 30.071 V after calibration. Flash update OK cell 3724 V populated. The battery:  lithium iron battery.

Issue: The current voltage calibration is biased, 26 V calibrated, and for other voltages, the deviation is around 1 V. For example, 27.048 V for 28 V, 24.864 for 24 V. 25.960 for 26 V. The customer would like to know what's the reason for that.

Thanks a lot!

Best Regards,

Cherry

  • Hello Cherry,

    You can calibrate voltage and current using bqStudio calibration feature.

  • Hello,

    Thanks for your reply!

    The customer dose use bqStudio.

    1. After re-burning the srec file, bqstudio shows that it goes to 586 mV 32726 current, but it is still not charged and discharged on the 26-V battery. And then the BQ34Z100 cannot be recognized now.

    2. When using the LED light, do not press the switch button, and the BAT pin is out of voltage, how to calibrate this time? press and hold the switch to calibrate?

    Could you help to check this?

    Thanks!

    Best Regards,

    Cherry

  • Hello Cherry,

    I would point customer to this document

    https://www.ti.com/lit/ug/sluubv2/sluubv2.pdf

    This document links to another document that has full details.

  • Hi,

    Thanks for your help, and the customer cannot find the solution from the document you provided, could you please check the 2 questions again?

    1. After re-burning the srec file, bqstudio shows that it goes to 586 mV 32726 current, but it is still not charged and discharged on the 26-V battery. And then the BQ34Z100 cannot be recognized now.

    2. When using the LED light, do not press the switch button, and the BAT pin is out of voltage, how to calibrate this time? press and hold the switch to calibrate?

    Thank you so much!

    Best Regards,

    Cherry

  • Hello Cherry,

    1. A lot depends on which srec was programmed If the default srec was programmed, then power cycle the board and follow the EVM guide. If another srec was programmed, then make sure to apply the same voltage divider as the pack from which the srec was read. If the bq34z100 is not being recognized, then check all connections and that bqStudio can communicate with another device on the same bus before trying again.

    2. For voltage calibration apply the reference voltage to the pin as directed in the calibration window.

  • Hello,

    Thanks for your patient reply! But the customer still cannot figure out the issue:

    1. Is it necessary to hold down the switch to ensure that the BAT pin has around 900 mV to calibrate the total voltage?

    2. what causes the calibration deviation to be so large?

    3. For this issue,

    And then the BQ34Z100 cannot be recognized now.

    the communication line is ok, the customer suspects may calibration causes the issue.

    Thanks again and looking forward to your reply!

    Best Regards,

    Cherry

  • Hello Cherry,

    The LED switch is not related to calibration. If you meant some other switch, then let me know.

    A stable voltage needs to be applied to BAT pin externally for calibration, Calibration must be performed before cells are attached.

  • Hi,

    Thanks for your reply! And the customer has a follow-up question:

    Normally, without pressing the LED switch, there is no voltage input to the BAT pin, and the IC only has the REGIN pin to supply the constant voltage, how is the total voltage derived?

    Thanks and Best Regards,

    Cherry

  • Hello Cherry,

    I don't think that is normal but i may be wrong. Are you seeing this on the TI EVM?

  • Cherry

        You  do not need to press the LED switch to do calibration if you are doing this with TI EVM, just apply a voltage to the BAT input of the EVM, and proceed to the calibration page to put in the actual voltage value and calibrate

        My voltage reading after calibrating at 16030mV are as following:

        real voltage(mV)         Gauge Reported Voltage(mV)

         16030                         16030

         14124                          14124

         18388                          18386

         10666                          10667

  • Hi Steven,

    Thanks for your reply.

    The customer just use a normal board, not like EVM, and the BAT pin has no peripheral interface.

    Could you help check it again? Thanks a lot.

    Best Regards,

    Cherry

  • Cherry

        Can you provide customer schematic? There should always be voltage divider on BAT pin

  • Hi Steven,

    Once you did not press SW1 down, Q5 does not turn on, and there is no voltage at the BAT pin.

    Thanks and BR,

    Cherry

  • Cherry

         Can gauge report voltage if you do not press SW1 done?