Foreign object detection calibration was also performed on this device to make sure that the device met Qi standards. The resistors that are modified are R13, R12, and R10. The adjustments to these resistors are based on the following information:

• R13 is adjusted to change the impact of the current on the reported power loss. This changes the slope of a power loss versus current plot
• R10 is calibrated to adjust the loss when the power output is low. This affects the offset of the data points on a power loss versus current plot
• R12 is adjusted to maintain a 1 A current limit.

Each adjustment is made after measuring the reported power loss as a function of current output from the BQ51013B-Q1. This was done until the power loss met the Qi standards for FOD. Qi standards require that the power loss reported across the expected load to be between -25 mW and -350 mW.

It was found that the values R13 = 210 Ω, R12 = 106 Ω, and R10 = 17 kΩ was a set of resistors that kept the power loss measurement between -25 mW and -350 mW across an expected current load. The data is shown in Figure 3-2.