Medically-approved 200W PSUs offer 95% efficiency and convection cooling

October 31, 2013 // By Graham Prophet
XP Power's CCB200 series of 200W single output AC-DC power supplies is aimed at a broad range of medical and industrial applications, that require convection cooling.

Using an open-frame format, the series has a typical efficiency of 94% and a maximum of 95%, with a flat efficiency curve across the entire operating load range above 20% of full load. This can amount, XP says, to reduction of losses (waste heat) of up to 50% compared to typical 200W supplies. The high efficiency has enabled the convection-cooled units to be packaged in an industry standard 76.2 x 127.0 x 36.32 mm (3.0 x 5.0 x 1.43 in.) outline, usually used for forced-cooled power supplies of this rating. No load power consumption is less than 0.5W.

The series conforms to the ANSI/AAMI ES60601-1 medical 3rd edition safety standard and has approval for use in body floating (BF) applications where a patient applied part is used without the need for a further isolation stage. The CCB200 also complies with the internationally recognised UL/EN609501-1 safety standard for IT equipment.

XP has profiled the steady-state temperature of each of the critical components in the design, and has achieved an even distribution of heat, with no component running much hotter than others, and with the average temperature being significantly lower than a typical supply of the same rating. In particular, electrolytic capacitors run at temperatures that will ensure long service life. The CCB200 employs a resonant half-bridge circuit configuration, with regulation implemented by controlling the input voltage to the main conversion stage; there are main and boost component in the input voltage,and control is exercised by varying the boost part.

The units CCB200 can deliver the full 200W continuous output power over an extended temperature range from – 20 to +70C without any derating, and up to +85C with derating (to 100W at 85C). The industry norm is typically + 50 degrees C before derating applies, XP says.

The technology employed in the CCB200 ensures the same high efficiency rating is achieved from 90 VAC input, unlike designs that have lower efficiencies