Power Electronics

Power Supply Delivers High Performance at High Temperatures

A compact ac-dc power supply from OPS Power LLC of Centennial, Colo., delivers as much as 700 W of 48-V output at temperatures beyond the usual 50°C limits of existing power supplies. Housed in a rack-mountable 1.75-in. × 5.0-in. × 10.5-in. package, the OPSG2-700-48 supply currently delivers its full 700 W of output, while operating from a 108-Vac to 264-Vac source. When the input voltage range is widened to the universal 90-Vac to 265-Vac range, the power supply delivers up to 600 W. The power supply consists of an EMI filter, a power factor corrected (PFC) boost stage and a dc-dc converter stage that outputs 48 V.

The OPSG2-700-48 delivers its rated power outputs across its entire operating temperature range of -40°C to 65°C. In contrast, other rack-mount power supplies may specify an operating range of just 0°C to 50°C. The operating temperature range specified for the OPSG2-700-48 refers specifically to the temperature measured on the power supply’s baseplate.

The power supply itself does not contain a fan but an external fan may be required, depending on the thermal environment in which the unit operates. In other words, if the environment is generating heat, then forced air cooling may be required. However, the company is currently modeling the thermal performance of its units with the expectation that the power supply will deliver the full rated power as long as a baseplate temperature of 65°C or less can be maintained and with as little as 25 LFM to 30 LFM of airflow (i.e., natural convection), depending on the mounting.

Despite this high level of performance, the company is planning to push its power capabilities and high temperature operation even further. The OPSG2-700-48 power supply currently is available for testing and will begin full production in early summer 2005.

The company also plans to extend the operating temperature ranges of future products to allow full power delivery at baseplate temperatures up to 85°C. Currently, the PFC front-end module can operate at that temperature, but extending this performance to the entire supply offering will expand the potential applications for the company.

The power supply also boasts high MTBF ratings. At a baseplate temperature of 25°C, MTBF is specified at 715,010 hr, using the Bellcore Standard TR-332 Issue 1, valid at time of evaluation. At a 65°C baseplate temperature, MTBF is rated at 78,987 hr. In addition, the OPSG2-700-48 achieves efficiencies as high as 91% at the full 700-W load with 240-Vac input.

The OPSG2-700-48 represents the second generation of the company’s 48-V power supply. The original, first-generation supply, which was introduced a few years ago, was a standalone unit that offered similar power ratings to the current model. The current model is about 1.5-in. longer than the first-generation power supply. However, the new model adds features such as active current sharing, N+1 redundancy and hot swap capability.

In addition, the OPSG2-700-48 is a rack-mountable unit that also provides mounting holes on the underside of the 5-lb unit, allowing it to be mounted directly to the side of a cabinet. In those applications, a standard Molex connector can be used to interface with the unit. Internally, the company switched from using toroid transformers in the first-generation product to planar magnetic transformers in the new model.

Pricing for the OPSG2-700-48 is $450 each, depending on volume. For additional information, visit www.powersupply.com or call 800-445-4824.

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