to that of Test Power Transmitter #MP1. NXP provides the conversion method and needs to get the
parameters on board at first. The TX would do auto-calibration and get parameters at the first time
powering up after flashed new image, and then these parameters are written to flash. Therefore, it is
necessary to make sure there is no object on the TX surface at the first time powering up after flashed new
image.
Figure 10 Quality factor threshold example
4.7.1 Free Resonance Q factor
The free resonance Q factor detection is to detect the decay rate of the resonance signal, as shown in
Figure 11
. With the system’s high Q, driving just a few pulses near resonant frequency are sufficient to
serve as impulses and start the system ringing. Collect ADC data of tank voltage (or coil current), and then
get the decay rate of the signal.
Q=
𝜋
/(-ln(Rate))
Rate is the value of decay rate of resonance signal.
WCT1011A/WCT1013A Automotive MP-A9 Wireless Charging Application User’s Guide, Rev. 0, 10/2017
NXP Semiconductors
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