XP claims first 250W AC/DC power supply to hit 95% efficiency

Removing the need for fans greatly increases reliability while reducing cost, audible noise, system complexity and size. Avoiding audible noise is particularly important in medical applications, where it disturbs patients. Both conducted and radiated emissions are below Class B limits as defined by EN55011, another important consideration in achieving type approval for medical equipment.



The power supply delivers full output with convection cooling over input voltages from 90 to 275VAC, and 200 Watts from 80VAC, in ambient temperatures of -10 to +50 degrees centigrade. It measures only 152.4 x 101.6 x 39.1 mm (6 x 4 x 1.54 inches), making it the smallest product in its class and ideal for fitting in 1U enclosures. Where short-term peak power is needed, for example for motor start-up, the power supply will deliver up to 300W for 500 ms.



The units have a full feature set for controlling the supply and external monitoring and control equipment. This includes a 5V standby rail, remote on/off switching and power fail signals.



The design of the CCM250 combines conventional and novel design techniques to achieve a step-function in power density and efficiency. A 3-stage converter using an interleaved, resonant, half-bridge, means that two relatively small transformers can replace one large one, saving board space. A zero current, virtually lossless switching topology for the main converter ensures high efficiency over a wide load range and contributes to exceptional EMI performance. A crystal-controlled clock and digitally generated drive signals are used to ensure accurate, fixed-frequency timing for switching transistors. The power supply's footprint is minimised through innovative mechanical construction. Heat-generating parts are bonded directly to the U-channel chassis, and magnetic components are conduction-cooled, enabling the use of smaller parts.

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