Application Note
20 of 36
002-34970 Rev. **
2022-05-03
Foreign object detection tuning guide for wireless power transmitters
Applicable for WLC ICs
FOD parameter tuning
S. no.
Parameter
Description
4
Prepower Q FOD threshold (%)
Q factor threshold for FO detection when there is no
communication.
Default value is 30.
5
No response digital ping retry
count
Object detected with no communication/response to
digital ping will retry for initiating communication.
Retry count expiry will enter into idle state.
Default value is 2.
6
Q MPA1 scale factor for Rx with
no friendly metals (%)
Scaling factor for TPRs with higher Q measurements.
Default value is 40%.
7
Q MPA1 scale factor for Rx with
friendly metals (%)
Scaling factor for TPRs with lower Q measurements.
Default value is 75%.
3.5
Resonance frequency scaling factor and threshold tuning process
The resonance frequency method is an improvement of the pre-power transfer of the FOD mechanism using
Q factor. The experiments show that the resonance frequency-based FO is more efficient on Rx with friendly
metals, like smartphones, tablets and so on. A reference TPR for such devices is TPR#MP4. Hence the scaling
factor and threshold tuning process is based on the TPR#MP4.
Refer to section
for required tools and section
for setting up the hardware. Further steps for RF tuning
are applicable for TPR#MP4.
3.5.1
Resonance frequency scaling and threshold tuning process
The process involves capturing the measured resonance frequency values from the UART logs (as shown in
or alternatively use the digital signal oscilloscope or LCR Meter
.This section elaborates on using
system measurements available from the UART logs as shown below:
