Applied Power Electronics Conference (APEC) – Anaheim, CA – Feb. 26, 2007 - ON Semiconductor (Nasdaq: ONNN), a leading global supplier of power management solutions, today unveiled its latest GreenPoint™ reference design – this one for 40 watt (W) power supplies used to power desktop printers. The design is a blueprint that will help engineers quickly deliver power adapters to market that provide both low active-mode and low standby-mode power consumption.
Providing active-mode energy efficiency above 83 percent when delivering an output power between 5 W and 40 W, this reference design achieves a no-load power consumption of <150 milliwatts (mW). Typical 40 W printers in use today consume on average 450 mW in similar conditions. The frequency foldback technique implemented in the design, keeps the efficiency of the power supply very high under light load conditions. (e.g.: With an output power from 0.5 W to 2 W, the efficiency varies from 66 percent to 79 percent). The combination of these characteristics makes this GreenPoint™ reference design compliant with the most stringent requirements from ENERGY STAR® to the Group for Energy Efficient Appliances (GEEA) via the US Executive Order "1-Watt Standby" Order and the Japanese Eco Mark program.
“The new 40 watt printer power supply reference design joins our 200 W, 60 W and 90 W GreenPoint™ power adapter designs, and strengthens our position as the leading silicon semiconductor solution provider for energy efficient power”, said Andy Williams, senior vice president and general manager of ON Semiconductor’s Automotive and Power Regulation Group. “The ability of this design to improve a printer’s power supply efficiency by more than 12 percent in light load conditions and 2.5 percent under nominal load is further evidence that some of the most significant improvements in energy savings can be achieved through advanced silicon and system level design techniques that are extremely cost effective.”
The Reference Design
The new 40 W reference design enables a peak power of 80 W to be transiently delivered - a feature that makes it particularly suitable for printer applications. An over power protection below 100 W has been implemented for the entire input voltage range (88 ~ 265 Vac) to comply with the Limited Power Source (LPS) test. In addition, the design uses a smaller bulk capacitor than those typically utilized in 40 W power adapter designs with similar performance. This helps reduce both board space and the overall system cost.
The enabling device for the 40 W reference design is the newly introduced NCP1351
, a current mode controller targeting low power off-line flyback Switched Mode Power Supplies (SMPS). Based on a fixed peak current technique (quasi fixed TON), the controller decreases its switching frequency as the load becomes lighter. As a result, a power supply using the NCP1351 naturally offers excellent no-load power consumption, while optimizing the efficiency in other loading conditions. When the frequency decreases, the peak current is gradually reduced down to approximately 30 percent of the maximum peak current to prevent transformer mechanical resonance. The risk of acoustic noise is thus greatly diminished while keeping good standby power performance.
An externally adjustable timer permanently monitors the feedback activity and protects the supply in the presence of a short circuit or an overload. Once the timer elapses, NCP1351A and NCP1351C stop switching and stay latched, while NCP1351B and NCP1351D attempt restart. Both NCP1351C and NCP1351D feature a dual over current protection, a better fit for applications facing large output power transients. The internal structure of the device features an optimized arrangement which allows one of the lowest available startup currents, a fundamental parameter when designing low standby power supplies. The negative current sensing technique minimizes the impact of the switching noise on the controller operation and allows the user to select the maximum peak voltage across the current sense resistor. Power dissipation can then be optimized for the application.
The NCP1351 A, B, C and D are all offered in Pb-free SOIC-8 packages, and are priced at $0.32 per unit in 2,500 unit quantities.
A complete documentation package for the 40 W power adapter is available - including description, block diagram, schematic, bill-of-materials, Gerber images, and evaluation results. These materials are available at www.onsemi.com, as are the product specifications and other supporting information. For additional information, contact firstname.lastname@example.org.
GreenPoint™ reference designs enable more efficient systems by establishing the feasibility of meeting emerging energy efficiency standards with existing technology, and by setting performance benchmarks. ON Semiconductor’s GreenPoint™ reference designs are available for ATX, CRT TV, and LCD TV power supplies; and 40 W, 60 W, 90 W, and 200 W power adapters. To acquire documentation packages, visit www.onsemi.com and search on “GreenPoint”.
About ON Semiconductor
With its global logistics network and strong portfolio of power semiconductor devices, ON Semiconductor (Nasdaq: ONNN) is a preferred supplier of power solutions to engineers, purchasing professionals, distributors and contract manufacturers in the power supply, computer, consumer, portable/wireless, automotive and industrial markets. For more information, please visit ON Semiconductor’s website at https://www.onsemi.com.
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