6.78M，楼主你看的什么文档？我手里的QI1.0标准是110k～205k。p42原文如下“Power Transmitter design A5 uses the Operating Frequency and duty cycle of the Power Signal in order to control the amount of power that is transferred. For this purpose, the Operating Frequency range of the full-bridge inverter is  110...205  kHz with a duty cycle of 50%;

因为6.78MHz是ISM频段之一。