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bq51050b charger detection

Karl Ravn
Prodigy 20 points
Other Parts Discussed in Thread: BQ51050B, BQ51025, BQ500511A

Hi,

We are planning on introducing the bq51050b into our product instead of our current USB port charger. The question we have is that we would like to know when the product is lying in the induction charger cradle, not only when it is actually charging. The CHG port (as I have understood) is only active low when the product is charging, and when it detects the battery to be full, it will be floating/high?

What I'm looking for is someone to explain how we basically can hook up to either of the coils to see if there is a charger nearby. The output we want is a steady low or high signal, that does not get cut off until the product is taken away from the carger. Up to 8v is ok.

  • 0
    TI__Genius 14890 points

    Karl,

    The bq51050B does not have a simple "pad detect" function.  The bq51025 receiver does have a PD_DET pin which enables a pad detect function.

    Using the bq51050B RECT pin may be able to provide a similar function.  A concern is how the transmitter reacts when the bq51050B sends a charge complete signal upon charge termination.  For example, the bq500511A transmitter will cease power transmission and will wait for 5 seconds to retry power transfer.  If the bq51050B still measures a full battery, the charge complete signal will be resent and the cycle continues.  

    During that retry after 5 seconds, the RECT pin is active to power the bq51050B.  That pin can be used to generate a signal - depending on what functionality of the system has available.  A microcontroller can use that signal to keep an LED or other notification active.

    Measure the RECT voltage during this time for maximum levels as can be tolerated in your system.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 20 points
    Hi Dick,

    This works just as we wanted! It works great and it does not seem to affect charging as we only use it as a signal and do not draw much current from it.