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BQ51003: Designing the bq51003 resonant capacitors using bq51003evm and bq500212aevm

Srujana Patel
Prodigy 250 points
Part Number: BQ51003
Other Parts Discussed in Thread: BQ500212AEVM-550, ,

Hello,

I am designing a receiver and a transmitter module for wireless charger using bq51003evm-764 and bq500212aevm-550 boards. I want to test the boards with different pairs of transmitter and receiver coils.

I have few doubts regarding the design and test processes. They are:

1. Are the transmitter resonant capacitors (C27,C28,C29,C30) to be changed everytime I  change the transmitter and receiver coils? To what frequency are these coils already calculated?

2. I know that I need to change the receiver side resonant capacitors (C1,C2,C3,C4,C5). But, to measure these capacitors, I need to use the test fixture mentioned on page 27 of the BQ51003 spec. document.

Here, they mentioned that I must apply 1V RMS voltage at 100 KHz frequency to measure Ls and Ls'. Where do I apply this 1V RMS voltage at 100KHz frequency? On the receiver EVM (across J1 and J2) or transmitter EVM (across J1 and J2)? And where do I measure the inductance (Ls and Ls')? Is it across TP2 and TP4 of receiver evm?

3. How to set the best-operating frequency to the setup after load-line analysis? Are these resonant capacitors just maintain and tune the module to a frequency range of 110-205KHz?

Expecting a quick reply soon.

Thanks & Regards,

Srujana Patel.

  • 0
    TI__Guru* 76486 points
    Hi Srujana

    See below answer also take a look at bq51003 data sheet "Series and Parallel Resonant Capacitor Selection" 9.2.1.2.2

    1. Are the transmitter resonant capacitors (C27,C28,C29,C30) to be changed everytime I change the transmitter and receiver coils? To what frequency are these coils already calculated?----Bill J-Tuned with RX coil and only retuned if the coil or mounting changes. This would be the mounting of RX coil or metal around it. Freq is 100kHz for C1 (Cs) and 1MHz for C2(Cd).

    2. I know that I need to change the receiver side resonant capacitors (C1,C2,C3,C4,C5). But, to measure these capacitors, I need to use the test fixture mentioned on page 27 of the BQ51003 spec. document.----Bill J-Yes, the coil L will change when placed on the TX and this fixture will simulate the TX. IF you are only using ONE TX and Qi certification is not required, then use that TX for the test.
    Here, they mentioned that I must apply 1V RMS voltage at 100 KHz frequency to measure Ls and Ls'. Where do I apply this 1V RMS voltage at 100KHz frequency? On the receiver EVM (across J1 and J2) or transmitter EVM (across J1 and J2)? And where do I measure the inductance (Ls and Ls')? Is it across TP2 and TP4 of receiver evm?---Bill J.- the LCR meter used for measuring inductance will be set to 100kHz and 1V RMS. The measurement is on the RX coil with no connection to circuit.

    3. How to set the best-operating frequency to the setup after load-line analysis? Are these resonant capacitors just maintain and tune the module to a frequency range of 110-205KHz?---Bill J - this is a special test fixture that will be used to operate the coil in and open loop configuration.