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Difference between bq51013A DevKit and my own solution

Other Parts Discussed in Thread: BQ51013A

Hi everybody,

I'm developing a tool and therefore I would use wireless charging to charge my supercaps.

I have the bq51013a DevKit here and I also build up my own little board for some tests. The problem I have is that my own board can't deliver more than 80mA.

I compared each signal an pin voltage and everything is equal to the DevKit, witout the communication. When I'm meassuring the voltage between TP2 and TP11 of the DevKit, it seems like the communcation has a higher voltage value then the normal power transmission. When I'm meassuring the same points at my own board, the communication voltage is less than the normal transmission voltage.

I think thats the reason for the curent deliver problem, cause if current consumption at output increases there is no differens between transmittion with and without communication. At DevKit there is a difference.

Can you help me please, cause I don't know what to do know. I've used same values of capacitors and resistors as in the DevKit and I also calculated the new capacitor values for the smaller coil I'm using.

Thank you.

  • Hi,

     

    Please make sure to tune the resonant caps (C1 to C5) according to the final configuration and the final coil. Also in your board, you can increase the COMM caps to improve communication.

     

    Thanks!

    Tahar  

     

  • Hi Tahar,

    I will change the COMM Caps and test them with 68nF. Maybe this could help.

    But I've already calculated the Caps C1 to C5. with the right values for the coil I'm using it's also not working correctly.

    Regards,

    Denny

    Edit: Ive changed the Caps and the communication was getting better, but the current increased. So I build up a second board, what is exactly the same with the same capacitors and resistors and this time it works. Is it possible, that the thermal pad had not enough contact to get the heat away from the chip?

    thx