Patent ID: 11936207
Assignee: CYPRESS SEMICONDUCTOR CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 0:
1. A method of foreign object detection by a wireless power delivery system that comprises a Universal Serial Bus-Power Delivery (USB-PD) controller, the method comprising:
detecting, by the USB-PD controller, a decaying coil voltage signal of a transmitting coil of the wireless power delivery system;
using a first comparator of the USB-PD controller to trigger a cycle count of the decaying coil voltage signal, wherein the decaying coil voltage signal is an input signal of the first comparator;
when the first comparator triggers the cycle count, using a second comparator of the USB-PD controller to count a number of cycles of the decaying coil voltage signal, wherein the decaying coil voltage signal is an input signal of the second comparator;
determining a quality factor (Q-factor) of the transmitting coil based on the number of cycles of the decaying coil voltage signal, a reference signal of the first comparator, and a reference signal of the second comparator; and
determining whether a foreign object is present based on the Q-factor and a foreign object detection (FOD) threshold level.