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BQ2004: Delta T/ Delta t termination condition

Kevin Cerutti
Prodigy 100 points
Part Number: BQ2004

Hello,

I have two questions about the termination condition of the BQ2004, we are using it with a 4x AA VH 1900 cell battery pack.

  • Is it possible to use the  Delta T/ Delta t  and the maximum voltage termination conditions at the same time ?
  • How to implement the  Delta T/ Delta t termination condition, taking account that the battery pack NTC resistance value change inconstantly with the temperature.

The NTC reference is 103AT-2, from Semitec.

Thanks,

Kevin

  • 0
    TI__Mastermind 24075 points

    Hi Kevin,

        Yes, Delta T/ Delta t and maximum voltage detection (Peak Voltage Detection (PVD)) will occur simultaneously and if one or more of these conditions are satisfied, then termination will occur. For PVD, VSEL should be pulled high, and for -delta V, VSEL should be left floating.

        Resistance of NTC changing is how the charger actually detects temperature changes of the battery pack, as the change in resistance will change the voltage sensed by the charger IC at TS (temperature sense). This is how BQ2004 can measure if delta T/delta t condition is hit or if VLTF (low termperature fault) or VHTF (high temperature faultt) are hit. The bq2004 samples at the voltage at the TS pin every 34s, and compares it to the value measured two samples earlier. If VTEMP has fallen 16mV ±4mV or more, fast charge is terminated.

  • 0 in reply to Kedar Manishankar
    Prodigy 100 points

    Hi Kedar,

    Thanks for your quick answer.

    I have two other questions :

    • By default, to how many C°/min correspond the fall of 16 mV/min ?

    • And is it possible to set a value of C°/min that will terminate the fast charge , for example 0.6 C°/min ?

    Regards,

    Kevin Cerutti

  • 0 in reply to Kevin Cerutti
    TI__Mastermind 24075 points

    Resolved in other post.