TDK-Lambda's CUS250M series is a 2" x 4" 250 W power supply with a mechanical layout that allows the device to achieve convection and conduction cooling through the base plate, providing silent cooling. The series has been certified to the industrial IEC 62368-1 and Medical IEC 60601-1 standards for Class I and Class II (no grounding) facilities. Applications include medical, home health, dental, testing, measurement, broadcasting, professional audio and industrial equipment.

     The CUS250M series offers 12 V and 24 V output voltages. The output can also be adjusted to accommodate non-standard voltages. The CUS250M has a working input voltage range of 85 VAC to 264 VAC and has a low ground leakage current of less than 150 µA, including all tolerances. Touch current 10 µA (Class I) and < 70 µA (Class II).

     The CUS250M provides up to 250 W of power at ambient temperatures from -20°C to +50°C when conducting cooling in the absence of outside air. It can also operate at temperatures up to +80°C with appropriate derating. Up to 125 W of output power can be achieved at +70°C using an external airflow of 1 m/s or an optional integrated fan, as the power supply is up to 94% efficient and generates less internal heat. The average efficiency measured at 25%, 50%, 75%, and 100% loads is greater than 91%, and the unloading power consumption at output suppression is less than 0.5W.

     Options for the CUS250M include 5 V 0.1A standby voltage, remote on/off (disable or enable), DC OK and AC fault signals, and open frame, U channel, U channel with cover, or top mounted fan mechanical construction.

     The product is designed to minimize the thermal degradation of electrolytic capacitors. Polymer output capacitors are used to provide low ESR and high ripple current tolerances. High voltage large capacity energy storage capacitors are located on the edge of the PCB to minimize temperature rise. Element layout improves convection and forced ventilation for cooling, which improves reliability and extends field life. Careful component layout at the bottom of the PCB improves heat transfer by evenly distributing heat throughout the base. The unique output terminal/choke combination (patent application) reduces common-mode output noise.

Input-to-output isolation of 4,000 VAC (2 x MoPP), input-to-ground isolation of 1,500 VAC (1 x MoPP), and output-to-ground isolation of 1,500 VAC (1 x MoPP) for B and BF grade medical devices. Safety certification complies with IEC/EN 60601-1, ES 60601-1 and IEC/EN/CSA/UL 62368-1, and CE/UKCA marking complies with low voltage, EMC and RoHS directives. CUS250M complies with IEC/EN 60335-1 and IEC/EN 61010-1 standards. The series complies with EN 55011-B, EN 55032-B radiation and conducted noise standards (Classes I and II) and with EN 60601-1-2:415 (4th edition) and EN 61000-4 immunity standards.