An electronic system is disclosed. The electronic system is electrically connected to an alternative current (AC) power and includes a switch and a parallel power conversion device. The parallel power conversion device includes a first power conversion module, a second power conversion module, and a driver. The first power conversion module is electrically connected to the AC power source and the switch, the second power conversion module is electrically connected to the AC power source, and the driver is electrically connected to the second power conversion module. When a current outputted from the first power conversion module is smaller than a specific vale, the driver makes the second power conversion module operate in a sleep mode to stop outputting current and to reduce level of outputting voltage.