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AC/DC power supply boasts 95% efficiency

Posted: 26 Jun 2009 ?? ?Print Version ?Bookmark and Share

Keywords:power supply? AC/DC? medical equipment?

AC/DC power supply

XP Power has launched a 250W AC/DC power supply that achieves 95 percent efficiency compared to competing products that operate at 90 percent maximum efficiency. The device targets medical, IT and industrial systems.

Ten percent of the input energy is usually converted to waste heat that needs to be removed. The five percent improvement in efficiency offered by the CCM250 means that it dissipates only half the heat, reducing or eliminating the requirement for heat sinks, or fans for forced-air cooling. This 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 90Vac to 275Vac, and 200W from 80Vac, in ambient temperatures of -10C to +50C. It measures only 152.4mm x101.6mm x 39.1mm, making it the smallest product in its class and suitable 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 500ms. 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.

Novel design
The design of the CCM250 combines conventional and novel design techniques to achieve a step-function in power density and efficiency. A three-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 minimized 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.

The CCM250 is available in sample quantities now, priced from $195 each in OEM quantities from Newark or direct from XP Power.

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