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BQ27220: sharing Thermistor with BQ25120A

Nicholas Carley
Genius 9885 points
Part Number: BQ27220

From the datasheet there is the impression that the BIN input is meant to be connected to the PCM thermistor and will not interfere with the PCM thermistor reading circuit. In our application I would like to connect it to the thermistor that we have connected to the BQ25120AYFPR charger.

Can you point me to the specification for the input impedance of the BIN pin or confirm that connecting BIN will not interfere with the measurement?

  • 0
    TI__Guru 52115 points

    The thermistor should only owned by bq27220 itself and cannot be shared. 

  • 0 in reply to Andy Liu (BMS)
    TI__Genius 9885 points

    We would like to use the JEITA current control compensation based on the pack temperature however, a feature of the BQ25120AYFPR.

    We could potentially leave the thermistor connected to the charger IC and also connect it to our host MCU ADC to calculate the pack temperature and write this to the fuel gauge over I2C. Unfortunately it doesn't seem that you can do this the other way around (write the temperate to the charger over I2C) and this wouldn't work while the battery is charging and the MCU power is turned off anyways.

    Any thoughts on this?