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Coil current

Benjamin Izquierdo
Prodigy 135 points


Hello,

Would it be possible to know the approximate current that circulates through the transmitting coil terminals? We want to do some tests and this information would be really helpful to choose the components. The scenario would be that of a maximum 5W power delivery at the receiver's output.

Thanks for any help you can provide.

Benjamin

  • 0
    TI__Guru* 76376 points

    The converter is a resonate converter topology with large circulating current between the coil and capacitors. Phase of the voltage and current come into play also.  Analysis of this is not straight forward.

    Also typical system efficiency is 70%, to deliver 5W out the input power will increase to 7W.  But efficiency can decrease below this point though misalignment of receiver coil to transmitter coil.  This will make the load hard to predict.

    Our recommendation for current rating of the MOSFETS,coil, capacitors and related traces is 2A.  Increasing beyond that point will reduce losses and improve efficiency.

     

    B/R

    Bill

  • 0 in reply to Bill Johns
    Prodigy 135 points

    Thanks for your answer Bill,

    We will work under those assumptions and take into account your advice on traces resistance.

    Benjamin

  • 0 in reply to Bill Johns
    Prodigy 10 points

     

    Hi Bill,

    I'm quite interested in that when there is a misalignment of receiver coil to transmitter coil, what happens for the frequency? Is it higher or lower than that of well aligned?