Compact 250 W medical and industrial power supplies with a 2×4 inch footprint are conduction or convection cooled

TDK Corporation (TSE 6762) introduces the TDK-Lambda 2” x 4” CUS250M series 250W AC-DC power supplies. The power supplies are IEC 60601-1 and IEC 62368-1 certified for both Class I and Class II (double insulated) installations. They can be used in equipment for use in home care and dentistry, as well as medical, test and measurement, broadcasting, professional audio and industrial equipment.

Conduction and convection cooling enable quiet operation of the CUS250M, which can deliver up to 250 W of power at ambient temperatures between -20 °C and +50 °C. They can operate up to +80 °C, although derating may occur. With forced air cooling through 1 m/s system air flow or an optional integrated fan, the U-profile versions can deliver 250 W at 50 °C, with derating to 125 W at +70 °C. Options for the CUS250M include a 5 V/0.1 A standby voltage, remote on/off, DC OK and AC Fail signaling and a choice of mechanical constructions with a U-profile, U-profile with cover or with a fan at the top .

For the time being, versions are available with 12 V and 24 V output; versions with 15 V, 18 V, 28 V, 36 V and 48 V follow. The output voltage can be adjusted by the user. The power supplies are suitable for input voltages from 85 to 264 VAC and have a leakage current of less than 150 µA. The touch current is <10 µA (Class I) and <70 µA (Class II).

With efficiencies up to 94%, less internal heat is generated, which improves reliable operation. The average efficiency, measured at loads of 25, 50, 75 and 100%, is more than 91%. The power supply consumes less than 0.5 W at no load with the output switched off.

One of the design features is the use of polymer output capacitors, which provide low ESR and high ripple current tolerance for maximum operating life. The high-voltage bulk capacitor, used to store energy during brief interruptions in the power supply, is located on the edge of the power supply PCB. In combination with the further layout of the components, this enables more effective cooling, both in convection and forced air applications. This also benefits reliability. Careful placement of the components on the underside of the circuit board distributes heat evenly across the underside, improving thermal transmission. A unique combination of output terminals and choke (patent pending) reduces common mode noise.

The CUS250M has an insulation voltage between input and output of 4,000 VAC (2 x MoPP); between input and earth this is 1,500 VAC (1 x MoPP) and between output and earth 1,500 VAC (1 x MoPP). This makes the power supplies suitable for B and BF classified medical equipment. Safety certification is to IEC/EN 60601-1, ES 60601-1 and IEC/EN/CSA/UL 62368-1, with CE/UKCA markings for the Low Voltage, EMC and RoHS Directives. The power supplies also comply with the EN 55011-B and EN 55032-B standards for conducted and radiated emissions (Class I and II) and the EN 60601-1-2:2015 (Edition 4) and EN 61000-4 standards in the field of immunity.

For more information about the TDK-Lambda CUS250M series, please contact TDK-Lambda Netherlands by telephone +33 (0) 6 72 83 75 77 or email info@nl.tdk-lambda.com. Or visit the TDK-Lambda website: www.emea.lambda.tdk.com/nl/cus250m