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BQ78Z100: Charge and Discharge Register

Ray Vincent Aranzaso
Mastermind 18180 points
Part Number: BQ78Z100
Other Parts Discussed in Thread: BQSTUDIO

Hi,

Good Day. I have a customer who is working with BQ78Z100. Please see below his query for your reference. Thank you very much.

I would like to easily disable the charge and discharge independently.

I am a bit lost in the documentation about a register described in the product datasheet:

“”"
8.3.13 N-Channel Protection FET Drive
The bq78z100 device controls two external N-Channel MOSFETs in a back-to-back configuration for battery protection. The charge (CHG) and discharge (DSG) FETs are automatically disabled if a safety fault (AOLD, ASSC, ASCD, SOV) is detected, and can also be manually turned off using AFE_CONTROL[CHGEN, DSGEN] = 0, 0. When the gate drive is disabled, an internal circuit discharges CHG to VC2 and DSG to PACK
“”"

If I understand correctly, the FETs can be disabled by changing this register. However, I tried to find this register in the product manual, but didn’t find it, same in BQStudio.

So my questions are simple:

Where is this register?
If it doesn’t exist, is there a way of enabling and disabling the CHG and DSG FETs independently?

Best Regards,

Ray Vincent

  • 0
    TI__Guru** 105590 points

    Hello Ray Vincent,

    The bits the datasheet is referring to are internal AFE registers that the gauge uses to directly enable or disable the FETs. The gauge is designed so the protections are configured and the host does not enable or disable the FETs, it acts with the preset protection values. If you want to enable or disable for testing you can send the FET_EN command and then toggle each FET using the CHG_FET and DSG_FET commands. If the host did have control and the gauge had control with it's protection, the two settings would constantly conflict, that's why we separate the two using the FET_EN.

    Sincerely,

    Wyatt Keller