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Voltage drop using BQ500410AEVM-085

alberto peralta
Prodigy 10 points

Hello 

I  am using the Tx board BQ500410AEVM-085 and the Rx board  BQ51013EVM-725. I have been using the same A6 coil the EVM  came with and changing the Rx coil ( changing resonating caps appropriately)  to compare difference in efficiency.

I am using the  BK  Precision 1672 Voltage  source set to 12V and 1A  current limit to power the Tx board. One thing noticed when using some type of Rx coils  is that once   the electronic  load is set to transfer power, the Vin drops from 12V  to 10.5-10.7V. I am still able to get good efficiency (>75%) and good power out (5.6W max) with this Vin. With other Rx coils, the power is transferred at 12V  in as expected. 

Is this drop in Vin because of a  difference in the transferred impedance the Tx coil sees? Is this an expected mode of operation for the BQ500410AEVM or should it always transfer power at 12V in. 

Thank you,

  • 0
    TI__Guru* 75906 points

    Input voltage should not drop---- "the Vin drops from 12V  to 10.5-10.7V. "

     We have not seen this issue in any of our testing.  It is possible that an inrush current at start up is resulting in unexpected behavior of the power supply.