The 255 W version exceeds 80 PLUS Silver, ENERGY STAR 5.0, and Climate Savers Computing Initiative Step 3 efficiency standards for desktop PC power supplies. The new reference design delivers improved efficiency under real world operating conditions, and in a configuration that allows it to be deployed immediately to production. The design provides a blueprint for power supply manufacturers to bring highly efficient power supplies to market with readily available, cost-effective technology.
Achieving a maximum efficiency of 90 percent at 50 percent load, and at 230 and 240 Vac, ON Semiconductor's reference design achieves greater than 88 percent efficiency at 50 percent load, and 100 and 115 Vac. Efficiency is greater than 85 percent at 20 percent and 100 percent loads, with 100, 115, 230, or 240 Vac. All efficiency measurements were obtained at the end of a 41 cm (16 in) cable, ensuring the design can be used 'as is' in all standard desktop PC configurations. Additionally, ON Semiconductor's ATX reference design meets IEC 61000-3-2 power factor requirements for power factor greater than 0.95 at 100, 115, 230, and 240 Vac.
“Our customers have indicated that while efficiency standards are important, real-world operating conditions – such as extended input voltage range and practical cable length – are equally important to actually deploy power supplies in end equipment”, said Bill Schromm, senior vice president and general manager of ON Semiconductor's Computing and Consumer Group. “In addition to ensuring compliance with the relevant global efficiency standards, we also addressed the real-world operating conditions that challenge our customers in their designs.”
“ON Semiconductor has steadily increased the performance of its ATX reference designs, since it became the first semiconductor company to achieve an 80 PLUS certified open reference design in 2005”, said Jason Boehlke, channel manager for Ecos Consulting and the 80 PLUS program. “The latest reference design from ON Semiconductor achieved the 80 PLUS Silver performance levels in a configuration that can be readily installed in production desktop PCs.”
The 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 standby power. The design utilizes several of ON Semiconductor's newest power management devices and draws from its leading discrete component portfolio to achieve efficiency performance.
Key products in the reference design include:
NCP1654 Continuous Conduction Mode (CCM) Power Factor Controller: Ideal solution for CCM PFC applications, such as ATX power supplies. The device enables the inclusion of a PFC front-end into an ATX power supply by simplifying the design through integration and providing a robust, cost-effective front-end without range switches. The NCP1654 is priced at $0.66 in 2,500-unit quantities, in SOIC-8 packages.
NCP1396 Resonant Mode Controller with High and Low Side Drivers: Integrated resonant tank solution, i.e., the leakage inductance of transformer acts as resonant inductance. The NCP1396 is priced at $0.85 in 2,500-unit quantities, in SOIC-8 packages.
NCP1027 65 kHz PWM Controller featuring 700 V MOSFET: Adjustable ramp compensation feature allows deep CCM operation, optimizing efficiency at full load. Skip mode operation optimizes light load efficiency. The NCP1027 is priced at $0.97 per unit in 1,000-unit quantities, in PDIP-7 packages.
NCP4302 Synchronous Rectification Controller: Highly Integrated Secondary Side Controller simplifies the implementation of synchronous rectification in switchmode power supplies, improving the overall system efficiency by two percent to four percent. In addition to the SR control, the device incorporates an accurate shunt regulator with TL431 functionality, reducing board space and system cost. The NCP4302 is priced at $0.74 per unit in 2,500-unit quantities, in SOIC-8 packages.
NCP1587 Synchronous Buck Controller: Built in non-overlap timing control prevents cross conduction of rectification MOSFETs. The NCP1587 is priced at $0.33 per unit in 2,500-unit quantities, in SOIC-8 packages.
MBR20L45 L-Series, 20 A, 45 V, Dual Schottky Rectifier: Low forward voltage drop minimizes power loss. The MBR20L45 is priced at $0.60 per unit in 50-unit quantities, in TO-220 packages.
NTD4809N Single N-Channel, 30 V, 58 A, Power MOSFET: Low RDS(ON) minimizes conduction losses; low capacitance minimizes driver losses; optimized gate charge minimizes switching losses.
The NTD4809N is priced at $0.19 per unit in 2,500-unit quantities, in DPAK and IPAK packages. All of these devices are RoHS compliant and are delivered in Pb-free packages. ON Semiconductor has a complete documentation package for the ATX reference design, including description, schematics, bill-of-materials, Gerber files, and evaluation guidelines.
The documentation package is available at www.onsemi.com/powersupplies
ON Semiconductor will demonstrate the GreenPoint 80 PLUS Silver certified open reference design at APEC in Washington, D.C., February 16-18, 2009 and IIC in Shenzhen, China, February 26-27, 2009.