Uninterruptible power supplies (UPS) play an important role in interfacing critical loads such as computers, communication systems, medical/life support systems, and industrial controls to the utility power grid. Among the various UPS topologies, on-line UPS provides maximum protection to such loads against any utility power problem as it protects against power blackouts and brownouts. However, because of the multiple power conversion stages, on-line UPSs have been the most complex and expensive type of systems. Today’s low cost, high-performance digital signal processor (DSP) controllers provide an improved and costeffective solution for on-line UPS design. By making them software controllable, we can add special features such as remote configuration and monitoring and other network management facilities. This paper discusses merits of digital controls over traditional analog conventions.