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BQ25172: STAT operation

Martin Dickman
Prodigy 10 points
Part Number: BQ25172

I am using the BQ25172 in a stand alone base charger for a single cell (button) NimH powered plugin device from a 5V USB connection (regulated PS or PC)

I have ISET=27K / VSET=47K / TS=10K (not used) / TMR=24K  connected as per the function schematic on data sheet, for an 8 hour charge at 10mA. as Vin is regulated I used this as the supply through a 1K2 resistor to the LED connected to STAT output pin .With no battery connected, the LED is ON and when the battery is connected the LED is OFF , opposite I was expecting. Is there a problem with the setup ?

  • 0
    TI__Guru 67676 points

    Hi Martin

    For an open battery condition the unit will charge output capacitor to Battey OVP point and set BAT OVP fault, LED will Blink at a 1Hz rate.

    Connect Battery and LED is OFF -- OFF will indicate Charge Complete.  If the battery voltage is 1.33V (1.305V  to 1.355V) at power on battery is considered charged, LED will be OFF and unit is in standby.