A wireless charging transmitter has a rectifier circuit, a transmitter coil, a transmitter coil driving circuit, and a control circuit. The rectifier circuit receives an alternating current (AC) mains input voltage and provides a rectified mains voltage. The transmitter coil is provided for inductively coupling with a receiver coil on a device having a battery to be charged. The transmitter coil driving circuit directly receives the rectified mains voltage, and for providing a time-varying driving signal to the transmitter coil. The control circuit is coupled to the transmitter coil to receive charging information from a receiver battery inductively coupled to the transmitter coil through load modulation. In response, the control circuit controls a frequency and duty cycle of the time-varying driving signal based at least in part on the charging information.