In 48-V-input telecommunications systems, power supplies with a capacity of 100 to 250 W are sufficient to cover many applications. Forward converters are a good choice for these applications. At lower output voltages, synchronous rectification in the secondary circuitry improves efficiency and simplifies system thermal design. Active-clamp forward converters work well in these applications because of the ease of implementing synchronous rectification. This paper presents the design of a 5-V, 300-W interleaved isolated supply that is powered from a standard 36- to 72-V telecom input.