XP Power Adds Fanless, Low-Noise 750W AC-DC Power Supplies

XP Power has introduced the UCH750 series, a family of 750 W convection-cooled AC-DC power supplies aimed at noise-sensitive medical and industrial equipment. The chassis-mount units don’t need fans to deliver full power, making the series one of the few fanless medical power supplies available at this power level.

Industrial targets include test and measurement, factory automation, semiconductor equipment, and telecom. Other applications include medical imaging, patient monitoring and treatment systems, diagnostic instruments, and home healthcare devices, where demand for quiet operation is growing. XP Power is also pitching the series at the increasing use of BF-rated equipment in hospitals, where patient protection and low leakage current are mandatory design constraints.

750 W convection-cooled AC-DC power supplies. Image used courtesy of XP Power

Inside the UCH750

The series accepts a universal single-phase input of 90 VAC to 264 VAC at 47 Hz to 63 Hz, with a power factor of at least 0.9 at 230 VAC and full load. Five models cover nominal single outputs of 12 V (62.5 A), 24 V (31.25 A), 36 V (20.83 A), 48 V (15.62 A), and 54 V (13.88 A).

According to the datasheet, full-load efficiency at 230 VAC ranges from 95% on the 12 V model to 96% on the 36 V, 48 V, and 54 V versions. Without airflow, every lost watt becomes heat that the enclosure must dissipate.

The enclosed U-channel package measures 203.2 mm x 127.0 mm x 40.0 mm, giving a power density of 11.9 W/in³. Full 750 W output is available from 100 VAC up to a 50°C ambient. Above that, output derates linearly to 50% at 70°C, and the datasheet notes that safety approvals apply only at 50 °C. Output also derates to 90% at 90 VAC.

A remote on/off input controls the main output, while a separate 5 VDC, 2 A standby rail stays live to power control circuitry when the main output is off. No-load input power is 0.21 W at 230 VAC with the main output disabled. Protections include overvoltage, overload with auto recovery, short circuit, and overtemperature.

Requirements for BF Rating

IEC 60601-1 classifies medical equipment parts that contact a patient into three types. Type B (Body) parts operate near or on the patient and may be grounded. Type BF (Body Floating) parts are isolated from ground, which limits the current that can flow through the patient if they contact mains voltage. Type CF (Cardiac Floating) parts are also floating but are intended for direct contact with the heart or bloodstream.

For B and BF parts, the patient leakage limit is 100 µA under normal conditions and 500 µA under a single fault. CF parts tighten those figures tenfold, to 10 µA and 50 µA. Floating parts may also help when several devices connect to one patient.

Thermal ratings are L1 & L2 coil, 130°C; T2 & T3 coil, 110°C; C9 and C43, 105°, and Q2 and Q500, 120°. Image used courtesy of XP Power

The UCH750 specifies a maximum patient leakage of 100 µA at 264 VAC and 60 Hz, the normal-condition limit for BF equipment. Earth leakage is rated at a maximum of 1 mA. Isolation is rated at 4,000 VAC input-to-output, meeting two means of patient protection (2xMOPP), with 1,500 VAC (1xMOPP) from input to earth and output to earth.

The supplies carry a CB report to IEC 60601-1 Edition 3.1, including risk management, along with ANSI/AAMI ES60601-1, CSA C22.2 No. 60601-1, and TÜV EN 60601-1 approvals.

The standard construction is Class II, which XP Power targets for medical and home healthcare equipment such as dialysis machines. A Class I version is available by dropping the “C2” suffix from the part number. On EMC, the units meet EN55032 Class B limits for conducted and radiated emissions and are immune to IEC 60601-1-2 Edition 4.1.

Why Convection Cooling?

Removing the fan eliminates acoustic noise in patient rooms and imaging suites and removes one of the few moving parts in a power supply, a component that can wear out and often fails first.

The UCH750 builds on XP Power's UCH600, launched in April 2020. That part used the same footprint at 9.5 W/in³ and up to 95% efficiency. The new series delivers 25% more power from the same package so that UCH600 designs could scale up without mechanical changes, subject to thermal validation. The UCH600 offered an optional 12 V fan output; the UCH750 datasheet lists none.

Fanless supplies at this power level aren’t unique, though. Bel Power Solutions released its MCC750 in January 2021, a 750 W natural-convection medical supply with 2xMOPP protection and 24 V or 48 V outputs. By comparison, the UCH750 offers five output voltages and a dedicated standby rail.