Industrial Electronics

2 inch x 4 inch 250 W medical and industrial power supply series extended to include five additional output voltages

11 April 2024

TDK Corporation announces additional output voltage models to the 250 W rated TDK-Lambda brand CUS250M series of power supplies in the industry standard 2 inch x 4 inch footprint. The full range now covers 12 V, 15 V, 18 V, 24 V, 28 V, 36 V and 48 V and is certified to the IEC 62368-1 and IEC 60601-1 safety standards for industrial and medical applications. This includes both Class I and Class II (no Earth ground required) installations.

The CUS250M has mechanical configurations that enable convection or conduction cooling through the product’s baseplate to provide silent cooling. Applications include medical, home healthcare, dental,Source: TDK Corporation Source: TDK Corporation test, measurement, broadcast, professional audio and industrial equipment.

The output can be adjusted to accommodate non-standard voltages, either by the factory or using the on-board potentiometer. The CUS250M operates across an 85 V AC to 264 V AC input and has a low Earth leakage current of less than 150µA — including all tolerances. The touch current is less than 10 µA (Class I) and less than 70 µA (Class II).

In ambient temperatures of -20° C to 45° C, the CUS250M can deliver up to 250 W conduction cooled without external air. With appropriate derating, operation at up to 80° C is also possible. With 1 m/s of external airflow, or the optional integral fan, at 70° C the series can provide an output power of up to 125 W. As the efficiency is up to 94%, less internal heat is generated, reducing component temperatures. The average efficiency, measured at 25%, 50%, 75% and 100% loads, is greater than 91%, and offload power consumption is less than 0.5 W when the output is inhibited.

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

The product design reduces electrolytic capacitor heat degradation, including the use of polymer output capacitors that offer a low equivalent series resistance (ESR) and high ripple current tolerance. The high-voltage energy storage capacitor is mounted on the edge of the PCB for minimum heat rise. The component layout enables more effective cooling for both convection and forced air applications, enhancing reliability and field life. Careful component layout on the underside of the PCB distributes heat evenly across the base, improving thermal transmission. A unique output terminal/choke combination (patent pending) reduces common mode output noise.

Input to output isolation is 4,000 V AC (2 times means of patient protection (MoPP)), input to ground isolation 1,500 V AC (1 x MoPP) and the output to ground isolation is 1,500 V AC (1 x MoPP) for B and BF rated medical equipment. Safety certification is to IEC/EN 60601-1, ES 60601-1. IEC/EN/CSA/UL 62368-1 standards and the CUS250M is CE/UKCA marked to the Low Voltage, EMC and RoHS Directives. The series is compliant with IEC/EN 60335-1 and IEC/EN 61010-1, meeting EN 55011-B, EN 55032-B radiated and conducted emissions with significant margins (both Class I and Class II) and complies with the EN 60601-1-2:2015 (Edition 4) and EN 61000-4 immunity standards.

Main applications

● Medical, home healthcare, dental, test, measurement, broadcast, professional audio and industrial equipment.

Main features and benefits

● Up to 250 W using convection and conduction cooling

● Medical certifications (2 x MOPP)

● High efficiency, up to 94%

● Class B conducted and radiated EMI with significant margins

● Compact 2 inch x 4 inch x 1.56 inch/50.8 mm x 101.6 mm x 39.5 mm size

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