Tag Archive for ‘Energy Efficiency’
July 26, 2010
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By Fairchild Semiconductor
Written by Wayne Seto, Technical Marketing Manager
With the proliferation of cellular mobile handsets, especially smartphones, in the world today where people are connected 24/7, consumers just can’t seem to get enough of the voice calls, emails, text messages and surfing the web. However, all of these activities greatly consume battery life in our handsets; as such, our handhelds lead to that one-bar battery power indicator very quickly. In this article from the June 1, 2010 edition of EDN Asia, Wayne Seto discusses what can be done to prolong the battery life for these handsets so that we can use them longer.
Read the complete article
Tags: efficiency, Energy Efficiency, Fairchild Semiconductor, power management
January 18, 2010
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By Benchmarks
Each quarter, Fairchild Semiconductor introduces new products, tips and tools for power and analog applications in the quarterly Benchmarks magazine. The following Benchmarks Volume 1, 2010 “Engineering Connections” article discusses flyback topology as an efficient solution for meeting today’s global demand for lowering power consumption in power supplies.
External power adapters are instrumental for the operation of virtually all small electronic devices. As many as 3.2 billion adapters are currently in use globally, according to industry estimates.
With this worldwide focus on energy savings, regulatory bodies are examining all ways to “go green,” and standards have been developed, specifying higher levels of efficiency for products such as notebook PC power supplies. Flyback topology has proven to be an effective solution, both in terms of cost and technology, for pulse-width modulated (PWM) power conversion in these products. Fairchild has a wide portfolio of PWM controllers that enhance the performance of flyback converters.
As part of its global focus on energy savings, Fairchild has developed a portfolio of pulse-width modulated (PWM) controllers, which enable notebook power-supply designers to meet the stringent international energy-saving regulations. These include the ENERGY STAR External Power Supply (EPS) version 2.0 requirement that mandates 87 percent average active-mode efficiency to obtain compliance.
Integrated PWM controllers, like the FAN6754, offer designers high-voltage startup to improve energy savings at light load by 25 percent when compared to alternate solutions. It also eliminates external protection circuits by incorporating over-voltage, over-current and over-temperature protection plus brownout and line-compensation functions. Other advantages of Fairchild’s PWM controllers include frequency hopping, which reduces EMI emissions by as much as 5-10 dB, and internal soft start (8ms) to reduce voltage stress on the MOSFET at startup.
Additionally, Fairchild’s PWM controllers incorporate several design features that lower the overall power consumption of notebook adapters, such as a proprietary green-mode function that provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Fairchild’s PWM devices offer a host of robust, accurate protection features built-in to protect the power supply and the load from failure, all without adding external components or circuitry.
Tags: Benchmarks, Energy Efficiency, Fairchild Semiconductor, flyback converter, green, PWM controller
December 21, 2009
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By DR. Efficiency
The power requirement of LED street lamps being used in China falls in the range of 100~250W. It is widely agreed that if used properly, these kinds of LED street lamps deliver many advantages. What I want to explain here is the ways to make it possible for these lamps to deliver those advantages. The key factors to be considered are high efficiency, power, reliability and cost-effectiveness.
Some low-power lighting requires PFC, while high-power lamps usually require PFC combined with DC/DC requirements. In China where the AC line voltage is 220V, Boundary-Conduction Mode (BCM) PFC controllers, such as the FAN7530 and the FAN6961, become the ideal choice to maintain a balance between the efficiency and performance-cost ratio. These solutions only need a few components.
Low Rds(on) SupreMOS(TM) MOSFETs, can further decrease switch and conduction loss. When used at the boost output, the HyperFAST 2 high voltage diode family with lower Vf can also lower the conduction loss of the diode itself.
For DC/DC topology, there are many choices such as quasi-resonant (QR), double transistor forward (DTF), active-clamp, LLC and asymmetrical half-bridge (AHB). High-power lighting applications, for example in a 100W lamp, where the output voltage is usually a little high, QR working with a synchronous rectifier can achieve up to 92.5% of total efficiency. Moreover, Fairchild has integrated QR and BCM PFC into one package (the FAN6921), reducing external components and simplifying the control.
Another popular topology is zero voltage switch (ZVS). Both an LLC and an AHB can have their two bridges working in zero voltage by implementing a simple circuit. When using Fairchild’s highly-integrated solution (for example, a LLC controller and two MOSFETs in FSFR; an AHB controller and two MOSFETs in FSFA2100), the circuit can be further simplified, with few external components. And the body diode of the MOSFET has good fast recovery characteristic, which can reduce the possibility of short-through, yet provide high reliability with high efficiency. When the output voltage is high, an LLC is the better option; when the output voltage is low, an AHB is more suitable for implementing a self-driven synchronous rectifier, and both can achieve over 93~94% efficiency.
The above solutions are highly integrated solutions and require just a few components, thus delivering high efficiency, high power density, optimized thermal performance as well as high reliability.
Click here for more information on LED lighting from Fairchild.
About the author:
Dr. Efficiency is a member of IEEE and the 85+ standards team as well as other prestigious electronic societies. He is the company’s expert in power efficiency, and when he’s not in the lab inventing he enjoys karaoke and table tennis and spending time with family and friends. He’s also passionate about blogging on all things related to energy efficiency.
Education: PhD in Electrical Engineering from Asia School of Engineering Tags: Energy Efficiency, Fairchild Semiconductor, LED Lighting
November 24, 2009
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By Alfred Hesener
PV inverter technology is driven by efficiency and compliance, but reliability is also important
What modern, ecological houses are wearing this season is blue - more precisely, the dark blue of solar cells. And this trend is gaining momentum, despite the financial crisis and reduction in feed-in tariffs from governments surprised by the success they created.
The owners of these systems are less concerned about the looks. What they are concerned about is high and reliable output. (Think of efficiency in the high 90s at more than 7000 power temperature cycles over lifetime!).
Green Power Feeding the Grid discusses how a good, reliable power switch must be the basis of this.
Tags: Energy Efficiency, green, inverter
June 15, 2009
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By Guy Moxey
By Guy Moxey, Low Voltage Power, Product Marketing
With the emergence of important climate saving legislation such as 80 PLUS, Climate Savers and EnergyStar® 5, analog designers for DC-DC power systems are striving to meet the challenge of increasing system level efficiency across all operating power states. From this, power silicon products such as power IC’s and power MOSFET’s are now very much in vogue as these devices create and dissipate the vast majority of any low voltage power conversion in-circuit losses that, in turn, directly relate to the system’s overall efficiency.
Take a typical notebook, typical peak efficiencies for a 46A, 2 phase Notebook VCORE solution with PWM controller and discrete MOSFET implementation are typically @90% peak at current ratings of 10A per phase, reducing down to @86% at full loads of 23A. This 10-13% loss in system efficiency is directly proportional to power and thermal dissipation. The complete notebook system is normally @ 50-60W output and running at 85% efficiency so that translates to a 9W power waste for every note book PC in the form of heat and battery life.
At start up or during a heavy processing sequence, the power system is dominated by conduction losses ( I2R) of the low side MOSFET. Here select a ultra high cell density low RDS(ON) FET housed in a dual sided cooled package so that the losses will be significantly minimized. However, as most PC s spend a majority of their operating life in standby or sleep states, it’s essential that the power system allows for light load efficiency management where gate drive and switching losses are predominant at low output currents below 10A. Here driver impedance and MOSFETs have to be carefully optimized. Gate drive voltages of 5V are preferred with MOSFETs with ultra low gate charge.
The driver IC can pulse skip switching cycles to minimize MOSFET switching loss and also low-drive disable to effectively blank out the low side MOSFET completely allow for discontinuous conduction mode operation.
By careful MOSFET selection, close optimization with the driver IC, the design can start to move toward a higher level of overall system efficiency. Full load thermal design points can inch upward toward the 90% level, medium to light load levels can be touching 95% and ultra light loads don’t immediately take a dive southward with such velocity. But while we progress and save a few watts of loss over today’s designs, there is still some significant silicon research and development to be done before the utopian power curve can be seen.
Tags: DC-DC power systems, Energy Efficiency, Fairchild Semiconductor, MOSFETs, power IC’s
