The UPS provides back-up power for Servers, large-scale network and other critical systems during power interruption or power failure conditions. Voltage stored in the UPS built-in battery pack supply power to an inverter equipped with DC boost circuit during power outage or failure conditions. Continued miniaturization of UPS systems require compact component design and low-noise and high efficiency operation. The power module can be used to provide DC power required for the inverter and for the microcontroller and other internal electronics. The low noise operation of the power module insures quiet as well as energy-saving high efficiency operation.