Fanless modular PSU outputs 600W from small 1U profile

June 16, 2016 // By Graham Prophet
Reliability is increasingly specified as a key parameter in power supply selection; and the single biggest detractor from reliability is a cooling fan; according to Excelsys, introducing its CoolX600 Series modular supplies that are rated for full output of 600W from a 8.5 x 4.5 in., 1U package.

The company positions the product as the only such modular, fanless supply available; and quotes an MTBF figure of 400,000 hours, with a 5-year warranty. It is a multiple-output, open-frame design that is rated at up to 94% efficiency: efficiency is preserved over a wide range of delivered power, only dropping to 90% below 25% of full load rating.


600W output is available with natural convection cooling, airflow required, and also does not depend on heatsinking or attachment to a cold wall. The PSU provides higher input surge protection of 4 kV Line to PE for operation in harsh environments, reverse energy protection without the use of external blocking diodes as well as safety certified operation at altitudes of up to 5000m. A 24W, medically isolated, auxiliary supply is available as a standard feature, offering effectively another output for system intelligence, control, displays etc. the company notes the very many equipment designs that, even in standby, are ‘always-on’ to the extent of requiring a monitor to be powered. The auxiliary output satisfies this need. Control of the supply can optionally be analogue or digital, via PMBus.


Excelsys (Cork, Ireland) says it has been able to achieve the product’s specification by careful design without using “exotic” devices or topologies – the supply employs silicon power switches and the company has not yet found it necessary to adopt, for example, GaN devices. It categorises the architecture as ‘modular resonant’; the design uses a high (380V) intermediate voltage, and advanced, multi-layer, planar transformer designs.


The CX06S is available with full safety certifications to IEC60950 2nd edition for industrial applications whereas the CX06M carries IEC60601-1 3rd edition & IEC60601-1-2 4th edition (EMC) for medical applications. Medical features include BF rating (Body Floating), dual fusing, 2 x MOPP, <300 µA leakage current. Other features include 4 kV input surge immunity and the ability to withstand input voltages of up to 300