Other Parts Discussed in Thread: BQ51003
Hello,
I built a Qi receiver circuit based on TIDA-00318 and the BQ51003 IC but I am finding the capacitor selection for the receiver coil's LC resonant tank to be strange.
The test report for TIDA-00318 shows a WR222230 27uH coil. The schematic shows that the C1+C2+C3 parallel capacitors are 0.183uF in total.
Using Equation 6 from bq51003 Highly Integrated Wireless Receiver Qi (WPC v1.2) Compliant Power Supply datasheet (Rev. C) (ti.com) and working backwards, it shows that the receiver's series resonant frequency is around 67kHz, which is much less than the expected 100kHz +5/-10% of a Qi circuit. (0.068+0.068+0.047)*10^{-6}= 1/((2pi*F)^2*27.9*1.1*10^{-6)} (symbolab.com)
In my design, the receiver coil is also around 27uH. Should I use the equation and recalculate the capacitor values, or should I respect the reference design and use the capacitor values from the reference schematic?
Thank you.
