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BQ51003 Pulsing

Craig Carder1
Intellectual 510 points
Other Parts Discussed in Thread: BQ51003

Hello,

   I've designed a circuit using the bq51003 and I am placing the transmit and receive coils in proximity.  I am seeing the output voltage of the BQ51003 pulsing and not quite getting up to voltage and holding.  I assume this may have to do with the EN and TS-CTRL input which I have controlled from a micro.  

   Would this behavior be caused by one of those input settings (I'm using the dual MOSFETs for the TS-CTRL input) or is this something else?

Thanks

Craig

  • 0
    TI__Genius 14890 points

    Craig,

    The TS/CTRL pin is a multi-function pin.  To determine if this causing issues, tie it through a 10k resistor to ground.  This effectively disables the TS function.

    EN1/EN2 can be left floating (internal pull-down) for debug purposes as well.

    Are you using a known good transmitter setup?  What is the spacing of the RX/TX coils?  What are the Ls and Ls' values for your coil (and how are the capacitors set in the AC1 line)?

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Intellectual 510 points
    Thanks Dick,

    I had a 10k resistor on the TS/CTRL line but I also had the two MOSFETs as shown in the datasheet. I think there were issues on power up and those MOSFET states were not correct. I removed the FETs and left the 10k and it works fine now.


    Thanks

    Craig