Reference design boosts ATX PSU efficiency

ON Semiconductor has unveiled the industry's first open ATX reference design certified to meet 80 Plus performance requirements for computing applications.

ON Semiconductor has unveiled the industry's first open ATX reference design certified to meet 80 Plus performance requirements for computing applications.

The 250W reference design addresses all functional blocks of the ATX power supply, including power factor correction, switch-mode power supply control and regulation, post regulation and output rectification.

The design uses several of ON Semiconductor's advanced power management devices and draws from its leading discrete component portfolio to achieve breakthrough performance.

"This certified 80 Plus ATX reference design demonstrates ON Semiconductor's commitment to delivering leading-edge power-efficient solutions to assist power supply designers in their quest to develop highly efficient power supplies", said Andy Williams, Vice President of ON Semiconductor's Power Conversion Division.

"We've worked closely with industry standards organisations and our customers worldwide to develop this economical 80 Plus compliant power solution".

"ON Semiconductor will continue to introduce additional GreenPoint power solutions to address the growing demand throughout the electronics industry for power efficiency in both active and standby modes".

80 Plus is a national buy-down programme administered by Ecos Consulting for desktop computers and desktop-derived servers that contain highly efficient power supplies.

The initiative challenges computer manufacturers to incorporate internal power supplies that operate at 80% efficiency (or better) across several load points.

ATX power supplies on the market today typically operate at 65% efficiency.

"ON Semiconductor's ATX power solution shows great initiative and clearly demonstrates it is possible to build an energy-efficient power supply that is also high performance", said Andrew Fanara, Director of Energy Star Product Development at the USEnvironmental Protection Agency.

"This reference design will definitely help move the 80 Plus programme forward and has very positive implications for eventual Energy Star certification".

In addition to passing rigorous internal testing, ON Semiconductor's ATX reference design prototype was independently tested and verified to comply with the 80 Plus programme by EPRI Solutions Corp in Knoxville, Tennessee.

Additionally, the ATX reference design meets IEC1000-3-2 power factor requirements.

"We salute ON Semiconductor for developing such an innovative 80 Plus design, and making it freely available to any manufacturer for use", said Chris Calwell, Policy and Research Director of Ecos Consulting.

"This solution demonstrates that it is both possible and affordable to meet the needs of customers that demand high efficiency and power factor correction today".

ON Semiconductor has prepared a complete documentation package for the ATX reference design, including description, schematic, bill-of-materials, Gerber images and evaluation guidelines.

The documentation package is available from the ON Semiconductor website, as are the verification and testing report, links to relevant industry information (80 Plus programme, IEC1000-3-2 requirements, ATX 12V form factor) and other supporting information.

Key products in the reference design include the following.

The NCP1653 is a compact power factor correction (PFC) controller that is ideal for continuous conduction mode (CCM) PFC applications.

This device makes the choice of incorporating a PFC front-end into an ATX design easy by reducing part count and providing a robust, cost-effective front-end without range switches.

The NCP1280 is an active clamp controller ideal for the switch mode power supply (SMPS) section of the ATX power supply.

With soft-switching capability and other unique features, this device assists in significantly enhancing the efficiency of the power stage.

The NCP1014 is a highly integrated regulator ideal for implementation in the standby/bias convertor section of the ATX power supply.

This device provides 10W standby power at high efficiency and with a lower part count than existing solutions.

The NCP4330 is a synchronous post-regulator that replaces the mag-amp post-regulator to provide higher efficiency in the output section of the ATX power supply.

The NTD110N02R and NTP65N02R are low-on-resistance N-channel MOSFETs that provide the pulsewidth modulation as part of the NCP4330 post-regulator.

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