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BQ25792: BATP Pin Resistance

AG
Prodigy 155 points
Part Number: BQ25792

Tool/software:

Hi Ti E2E,

The datasheet for the BQ25792 chip mentions

"Positive Input for Battery Voltage Sensing – Connect to the positive terminal of battery pack. Place 100Ω series resistance between this pin and the battery positive terminal."

What would happen if I used a 10Kohm resistor on that line instead of a 100ohm resistor? Would the BQ charger not be able to monitor the battery pack voltage as closely and cause charging issues?

  • +1
    TI__Guru**** 167196 points

    Hi AG,

    With in HiZ battery only mode, the charge pulls current into BATP to power the chip, including the SDRV pin that turns on the shipFET.  So higher BATP resistance is not supported due to voltage drop.  

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 155 points

    Hi Jeff,

    Can you share an example where HIZ on battery only mode would cause an interruption to the BQ25792 operation? Reviewing the datasheet for the chip, it looks like system power reset is a time when HIZ mode is required (to remove power output from VSYS) and with the 10K ohm resistor on the BATP line, an interruption would be expected due to a lack of power...however, when testing this function the BQ25792 chip performed its system power reset as commanded even with the 10K ohm resistance. Are there other modes or instances that the 10K BATP resistance would prevent the chip from Not working?

  • 0 in reply to AG
    TI__Guru**** 167196 points

    Hi AG,

    Frankly, I do not know as we have not tested.  I cannot warranty operation for BATP series resistance > 100 ohm.

    Regards,
    Jeff