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Original question:

BQ25172: No battery status issues

BQ25172: STAT status when there is no battery

Allen yang
Expert 1015 points
Part Number: BQ25172


Hi Team,

In the no-battery condition, a waveform with varying frequency was measured on the STAT pin.

1Hz or 5Hz

Are there any specifications or guidelines for this operating condition?

  • 0
    TI__Guru* 76346 points

    Hello

    In a no battery condition the BQ25172 will charge the output capacitor to OVP point then shutdown.  Output capacitor will discharge and to recharge point and cycle starts again.

    The STAT pin will go low during the charge phase, this is short about 500uS with no load and 1uF output capacitor. 

    If the output capacitor is increase it can show the fault condition caused by OVP, blinking of STAT pin.  

    A lot of the behavior of the STAT pin will depend on output capacitor size, charge current and load. 

    Couple of Output voltage points to note:

    OVP -- 1.7V / Cell

    OVP exit -- 1.45V / Cell

    Recharge -- 1.33V / Cell

  • 0 in reply to Bill Johns
    Expert 1015 points

    Output capacitor fixed

    Why is the STAT frequency different every time I remove the battery?

  • 0 in reply to Allen yang
    TI__Guru* 76346 points

    Hi Allen

    Allen yang said:
    Why is the STAT frequency different every time I remove the battery?

    In a no battery condition the STAT freq can vary due to a couple of factors.  Die temp can cause a shift in leakage current that will change discharge time.  Also some shift in the OVP trip point, this is due to rate of rise and deglitch time.  

    Increase the output capacitor will help to reduce the STAT frequency variation.