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BQ25170: Thermistor connection shared between BQ27220 and BQ25170

Siva R
Prodigy 100 points
Part Number: BQ25170
Other Parts Discussed in Thread: BQ27220

Tool/software:

Hi

   I have used BQ27220 and BQ25170JDSGR for fuel guage and charger IC respectively in my system. I have connected BIN pin and TS pin of BQ27220 and BQ25170 IC respectively with thermistor (10K) to ground. Now the value 400mV in TS pin is not coming and charging gets intermittent (ON and OFF). Kindly suggest us for charging it properly. In one of our board it is working properly but in other boards it is not charging intermittently. In other boards after removing fuel gauge IC, charging is done properly,fyi

Thanks

R.Sivasuryan

  • 0
    TI__Guru* 75906 points

    Hi R.Sivasuryan

    The Battery Pack NTC cannot be shared between Gauge and Charger.  

    Options on consider:

    1.) Connect NTC to Gauge and 10k resistor to Charger -- The Gauge / MCU would control charge vs temperature.  BQ25170 TS pin would be used as charge enable at desired temperature.  This would provide better Gauging over temp.  Also Battery Insertion Detection feature would be available.

    2.) Connect NTC to Charger and 10k resistor to Gauge -- The Charger would control charge vs temperature. 

  • 0 in reply to Bill Johns
    Prodigy 100 points

    Thanks, any software workaround (in BQ27220) for solving this issue as we have it in board.

  • 0 in reply to Siva R
    TI__Guru* 75906 points

    Hi R.Sivasuryan

    Checking on this question.  May need to loop in Fuel Gauge Team.

    See BQ27220 Tech Ref Manual,   Section 4.2.2, 4.3, and 2.5.