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PoE+ Circuit Delivers 13W to 70W for Powered Devices (PDs)  This application note presents a simple, cost-effective, pre-IEEE 802.3at PoE+ Powered Decice (PD) solution that employs the MAX5941B. The preliminary requirements of PoE+ PDs are discussed, as is the advantage of extending the existing MAX5941B circuit to implement a PoE+ PD. Test results including inrush-current limit, efficiency, output ripple, and dynamic response are presented for a 3.3V, 30W PD. Read more Inductance calculations with PerMag  This tutorial illustrates how to use finite-element codes to calculate inductance. The calculations address transmission lines in the limit that the radiation wavelength is long compared to the transverse dimensions of a structure. Read more Digital Power Helps Get Products to Market More Quickly  Power engineers have bigger and bigger challenges. Designs are more complex as the performance and capabilities of integrated circuits continues to increase. Digital solutions can help solve these issues facing today's design engineer. Digital power management addresses system level efficiency and does so while bringing products to market more quickly. The technology also provides enhanced communication and the ability to monitor, control, and configure minimizing system power and energy consumption. As companies look for new ways of gaining a competitive edge, digital power will be an avenue that many will increasingly choose to consider. Read more Comparing the Merits of Integrated Power Modules versus Discrete Regulators  Modern integration technologies have brought about improvements to the modular DC-DC voltage regulator. Time to market, cost, size constraints, reliability, and design capabilities are among the motivating factors in choosing modular power versus a traditional controller plus external components design. Each approach has its advantages and disadvantages. This article examines design criteria, performance, and BOM cost to predict the best choice for individual projects. Read more High Efficiency, High Power Factor TRIAC Dimmable 14 WTYP LED Driver  The document describes a high power-factor TRIAC dimmable LED driver designed to drive a nominal LED string voltage of 28 V at 0.5 A from an input voltage range of 90 VAC to 265 VAC. The LED driver utilizes the LNK406EG from the LinkSwitch-PH family of ICs. LinkSwitch-PH ICs allow the implementation of cost effective and low component count LED drivers which both meet power factor and harmonics limits but also offer enhanced end user experience. Read more Power Supply Design Just Became More Straightforward, Thanks to a New Interleaved PFC IC  This paper reviews the benefits provided by new advanced Power Factor Correction technologies. The efficiencies and compact size of interleaved PFC solutions are in perfect alignment with emerging green power supply requirements. The paper includes actual measured waveform diagrams, an evaluation board overview and most importantly some thought provoking ideas on novel product concepts. Read more High Efficiency, High Power Factor TRIAC Dimmable 7 WTYP LED Driver  This document describes a high power-factor corrected dimmable LED driver designed to drive 21 V at 0.33 A from an input voltage range of 90 VAC to 265 VAC. The LED driver utilizes the LNK403EG from Power Integrations. LinkSwitch-PH ICs allow the implementation of cost effective and low component count LED drivers which both meet power factor and harmonics limits but also offer enhanced end user experience. This includes ultra-wide dimming range, flicker free operation (even with low cost with AC line TRIAC dimmers) and fast, clean turn on. This document contains the LED driver specification, schematic, PCB diagram, bill of materials, transformer documentation and typical performance characteristics. Read more Using Lithium Polymer Batteries In Portable Devices  Lithium polymer batteries have become common in single-cell consumer applications like cell phones and MP3 players, but industrial and commercial applications are now putting them to good use as well. The thin and custom shaped cells are now used in large, complex packs. This white paper is an overview of the advantages, disadvantages and guidelines for using Lithium polymer based battery packs. It looks at Lithium polymer cells versus metal-cased cylindrical and prismatic Li-ion cells and gives a brief description of battery pack construction considerations. Read more Designing DC/DC Converters Based on ZETA Topology  Similar to the SEPIC DC/DC converter topology, the ZETA converter topology provides a positive output voltage from an input voltage that varies above and below the output voltage. The ZETA converter also needs two inductors and a series capacitor, sometimes called a flying capacitor. Unlike the SEPIC converter, which is configured with a standard boost converter, the ZETA converter is configured from a buck controller that drives a high-side PMOS FET. The ZETA converter is another option for regulating an unregulated input-power supply, like a low-cost wall wart. This article explains how to design a ZETA converter running in continuous-conduction mode (CCM) with a coupled inductor. Read more How the Voltage Reference Affects ADC Performance, Part 1  When designing a mixed-signal system which has an analog-to- digital converter (ADC), it is critical to understand how this device interacts with the voltage reference and voltage reference buffer. This article, the first of a three-part series, looks at the fundamental operation of an ADC independently, exactly as many designers do, and then at the performance characteristics that have an impact on the accuracy and repeatability of the system. Read more Reference Design for a Universal Input, 20W, LED Ballast  The LED Ballast requires a wide input voltage range (85 Vac to 265 Vac). This small size controller provides for a low cost, variable frequency, flyback converter-providing good line regulation with overload and short circuit protection, while incorporating a very low quiescent current. Read more Internetworked DC grids can save energy  Redwood System's vision is to transform how we power and control energy consumption in commercial buildings. By deploying a centralized power control platform for LED lighting, the Redwood architecture will incorporate a programmable “building fabric” using low cost discrete sensors to intelligently optimize where and how much power is needed for various applications. This architectural approach has the potential to save commercial buildings 75% of the energy consumed while providing a new platform for improved building intelligence. Read more Solving current source design challenges  An innovative new power IC from Linear Technology now provides system designers with a two-terminal current source. Until now, current sources were imprecise or had to be designed from other components. The new LT3092 200mA two-terminal current source overcomes the problems associated with previous current sources, with its wide voltage range, high AC and DC impedance, good regulation, low temperature coefficient, and the fact that it requires no capacitors. Read more Average current limit balances center point of half-bridge input caps  Half-bridge DC-DC converter topology suffers from the input capacitor divider imbalance during an overload event. This results in over design of components, adding to design cost. The average current limit is proposed to balance the input capacitor divider during an overload event while retaining all of the other features of traditional half-bridge controllers. Read more Speeding the adoption of smart meters and smart appliances  As the Smart Grid infrastructure is put in place, a wave of technology innovation will also sweep the home, introducing Smart Appliances that will enable consumers the necessary tools to reduce their carbon footprint. The opportunity is unprecedented as not only as businesses and consumers stand to benefit but the planet as well. The following paper provides detail on the Accent ASMgrid offering and how it can be applied to meet the challenges faced from Smart Meter to Smart Appliance manufacturers in terms of differentiation while reducing cost. Read more Basic Calculation of a Boost Converter's Power Stage  This application note gives the equations to calculate the power stage of a boost converter built with an IC with integrated switch and operating in continuous conduction mode. It is not intended to give details on the functionality of a boost converter or how to compensate a converter. Read more How to select the right CAPZero self powered IC to reduce losses in your converter design  CAPZero is a family of self powered ICs designed to reduce the losses associated with the input filter capacitor discharge resistors when the AC voltage is present. Designed to be connected in series with existing discharge resistors each CAPZero device contains an integrated loss of AC detector and back-to-back MOSFETs in an SO-8 package. Read more Power Optimization and Self-Tuning  Power optimization and power control are important and challenging issues for server computer systems. A system can be represented as a set of components whose cooperative interaction produces useful work. These components may be heterogeneous in nature and may vary in the power consumption and power control mechanisms. Server system components may coordinate power control actions using embedded controllers or special hardware. Generally, it is efficient to host monitoring and control functions to an out-of-band (OOB) controller. This avoids any side effects due to unavailability of the in-band controller or loading conditions that may themselves change the system properties. Learn more in this technical article. Read more Some tips for charging from USB sources part 1  Nearly all of the current and future released handheld devices are required to charge from USB sources and AC wall adapters. This presents several challenges for battery charging. In this article we will discuss features that simplify USB charging: Which features assist the user in designing a USB-compliant application? How does the design support both USB and AC adapter inputs? This article will discuss quiescent currents, input-voltage dynamic power management (VIN-DPM), and input-current limits, and the impact of the Chinese charger specification. The bq2407x series of ICs is used as examples to show these features. It is presented in two parts in pdf format. Read more Some tips for charging from USB sources - part 2  Nearly all of the current and future released handheld devices are required to charge from USB sources and AC wall adapters. This presents several challenges for battery charging. In this article we will discuss features that simplify USB charging: Which features assist the user in designing a USB-compliant application? How does the design support both USB and AC adapter inputs? This article will discuss quiescent currents, input-voltage dynamic power management (VIN-DPM), and input-current limits, and the impact of the Chinese charger specification. The bq2407x series of ICs is used as examples to show these features. It is presented in two parts. Read more
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