A power supply device including a switch arrangement including switches for generating a square wave output, a switch control arrangement for controlling the switch arrangement, a resonator tank, a rectifier circuitry for rectifying in an output from the tank, and a burst mode operation arrangement configured to facilitate a standby mode of the power supply and including a burst mode restriction arrangement for receiving and evaluating a first feedback parameter associated with a switch of the switch arrangement, the burst mode operation arrangement further receiving and evaluating a second feedback parameter indicative of the output voltage of the power supply device, and being configured to disable and enable the burst mode feature based on the evaluation of both the first feedback parameter and second feedback parameter by controlling an output from the burst mode operation arrangement.