Low-profile 60 W power pack for telecommunications systems

A low-profile 60 W power pack has been developed for use in telecommunications systems under natural convection cooling conditions. This power pack consists of four newly developed 15 W onboard power supply modules (OBPs). An OBP volume of 25 cm³ and an efficiency of 86% are achieved using a 500 kHz resonant reset single-ended forward converter with low loss diodes and Ag thick-film paste for high current conducting. To achieve the smallest possible OBP temperature increase, four OBPs are placed in parallel on the lower side of a card. Using these techniques yields a power pack only 9.2 mm wide, i.e., half the conventional width. Thus, this power pack can be assembled within a 15.24 mm pitch in a bookshelf unit. The circuit and physical design technologies used in this low-profile power pack are described, with special emphasis on the OBP circuit design and natural convection cooling design