 |
 |
||
|
Electromagnetic Compatibility (EMC) Society The Electromagnetic Compatibility Society (EMC-27) provides a networking environment for engineers involved in EMC test and/or design efforts. The EMC Society also provides a forum for sharing ideas and industry information. |
Application Notes & Articles > Coax Cable Coupling/Shielding > Coupling Between Lines at HF > Coupling of Transient Fields > Unshielded Line Susceptibility Components & Material > API Tech > Corcom > EE Seal > Isodyne > Laird > MAJR > Schlegel > Spira LI Test Labs > Retlif > UL LI EMI/EMC Reps > Advanced Technical Marketing > Mantec > Win-Cor Organizations > NARTE Publications Reference Standards & Handbooks > MIL-HDBK-704 (with notations) Standards Bodies > ATIS > ANSI > BSI > C63 > CENELEC > ETSI > FCC > IEC > ISO > MIL-US > NIST > RTCA Test Apparatus > Haefely > Keysight |
||
|
Past Lectures |
|||
|
Gallium nitride (GaN) technology has recently gained traction in power conversion applications due to the superior switching characteristics and improved figure of merit. Safety GaNs with low parasitic capacitance and zero reverse recovery lead to higher switching frequency and efficiency, opening up new applications and topology options. Continuous conduction mode (CCM) totem-pole PFC is an example topology that benefits from the GaN merits. Compared with commonly used dual-boost bridgeless PFC topologies, the CCM totem-pole bridgeless PFC reduces the number of semiconductor switches and boost inductors by half, while pushing peak efficiency above 98.5%. The root cause of current spike in the AC crossover region is analyzed and solutions are provided. A 750 W totem-pole PFC prototype is built to characterize the experimental safety GaN with an integrated gate driver and demonstrate the performance.
The presentation, Optimizer Based Loop Compensation of Voltage Mode Buck Regulators, will cover the classical method to compensate voltage mode control buck regulators using established calculation techniques and example circuit simulations to verify the method. Then a simulation based optimizer method will be introduced which can automatically calculate the component values of the compensator based on an initial pole/zero placement strategy. It will be shown that this strategy has high flexibility, reduces iterations and can be expanded to other topologies and compensator circuitry.
This primer offers a concise but informative overview of power supply technologies, covering traditional, high power SCR-based Delta-Y supplies, lower power linear power supplies, DC/DC switch-mode converters and DC/AC inverters. It outlines operational principles, applications, and notable features. This comprehensive yet succinct summary aims to equip engineers and researchers with fundamental insights into power supply engineering for various applications.
Component degradation in power electronic converters severely threatens the system's reliability. These components degrade over long operation time due to electrical, thermal, and mechanical stress. This calls for accurate monitoring of component health considering cost, accuracy, and adaptability. This paper develops and validates a real-time Digital Twin (DT)-based condition monitoring for Multi-Phase Interleaved Boost Converters (IBCs). The DT model employs state-space modeling to twin the real-physical hardware attributes and performance. Subsequently, outputs from both the physical hardware and the DT model undergo comparison to determine the least squared error in a multi-objective optimization setting. Techniques such as particle swarm optimization and the genetic algorithm are employed for assessing the health of the converter's components. Furthermore, this suggested approach can be adapted for various inductor coupling methods, functioning under both continuous-conduction-mode (CCM) and discontinuous-conduction-mode (DCM). The paper proposes decoupling and hybrid approaches to improve estimation accuracy by 9.4% and reduce embedded computational requirements by 22%, respectively. A 75 kW, 60 kHz SiC IBC hardware prototype is built and tested for concept validation.
This presentation provides an overview of the changes to C63.10-2020 and upcoming changes to the current version C63.26-2015. The FCC has recently proposed rulemaking to incorporate C63.10:2020 into its rules to test unlicensed wireless devices. There have been several updates to the 2013 edition of the standard, which is the currently referenced version in FCC rules. C63.26-2015 is currently under revision and this presentation highlights some of the important changes that will be coming in the next edition. Testing laboratories that test to FCC rules and regulations for both unlicensed and licensed wireless devices would benefit from this overview.
This presentation providea an update on the C63.25.1-2018 standard for site validation measurements for 1-18 GHz applications. The FCC has recently proposed rulemaking to incorporate the C63.25.1-2018 standard. The main contribution of the standard is the introduction of Time Domain Site VSWR (TD SVSWR) for validating an EMC test site for above 1 GHz applications. Commercial and in-house EMC Test Labs will benefit from a fast, precise site validation technique, as an option with equivalent results as the CISPR SVSWR method. TD SVSWR has also been proven as an effective chamber “debugging” tool that quickly identifies problems in a chamber that fails to meet performance test requirements. We will walk through the measurement steps and data processing so users will gain a better understanding of the method as well as the rationale and benefits of the TD SVSWR method
In avionics, widely used standards for power quality include MIL-STD-704 and RTCA DO-160. While both these standards are extremely detailed, there are areas where clarifications and additional conditions can help capture a more comprehensive suite of three-phase power failure modes that can occur in the field or during production tests. For example, in MIL-STD-704, it is not clear how a phase loss is defined. Although the accompanying handbook (MIL-HDBK-704) does clarify the fault definition (as a zero-volt potential) it is also likely that the fault can be caused by an open-circuit condition, which is not covered. Also not covered is the application of power to the Unit Under Test (UUT) with a pre-existing fault condition. DO-160 has a similar issue with the phase fault definition, but it does cover some cases where the UUT is energized with a pre-existing fault. Neither specification covers the loss of the neutral connection for wye loads.
The Smart Grid is an all encompassing term in today’s power distribution industry. The threat of equipment disruption and damage from transient surges is very real and can have dire consequences on the delivery of electricity to residential, commercial and industrial users. This session discusses the origins of how surges occur and the methods to mitigate these transients from sensitive electronic equipment. Also covered is an overview of IEEE standards for surge protection, as well as applicable safety standards.
Douglas Toth - Wurth Electronics Loss Calculations are covered along with the general equations for determining losses based on relationships of the Source to the Load. Simulation analysis is also discussed using the source to load ratio at a specific frequency to determine the effective impedance damping needed to meet EMI test limits. Also included are brief discussions on Common mode noise and Differential noise, the difference between the two and the proper filtering of each.
Mark Hendricks - Dehn This lecture discusses the methods, products and materials available to meet the requirements of the direct lightning strike waveforms described in MIL-STD-1757A and MIL-STD 464. The existing IEC, IEEE and UL lightning protection standards do not provide a clear correlation between accepted industry protection waveforms and those seen with the MIL-STD direct strike requirements. Specifically, this lecture provides detailed PSpice modeling and numerical analysis to compare the direct strike components in the military 1757A and 464C standards with the relevant IEC 62305 10/350us suggested direct strike waveforms. The results shown allows system designers to select commercially available products to achieve compliance with military standards with a high level of confidence.
Jason Smith - Absolute EMC FFT or Time Domain scanning technology has been around for a long time but only recently has been proven to be compliant to EMC standards. The technology can shorten test time, but its real benefit is more accurate testing. With this new technology it is important to know and understand the parameters so you can purchase the equipment and use it correctly. MIL-STD-461G and CISPR 16-1-1 have new terminology regarding the use of FFTs. Learn all the facts about the requirements to understand which FFT-based equipment will meet your needs.
David Dupre - AVX EMI and ESD requirements can be difficult to meet. The presentation discusses EMI and ESD basics and the design challenges created by these mandates, with a focus on noise and transient events.
Jon A. Rhan - Kemet The various dielectrics available and their pros and cons are discussed in addition to EMI suppression using capacitors, filter networks and other technologies. Related topics also explored include capacitor reliability and performance differences between capacitor types. While there are many considerations in choosing the proper capacitor for EMI applications, an online WEBSPICE tool can help determine what capacitors to use in an EMI/EMC network.
Lou Feudi - Ametek Compliance Test Solutions MIL STD 461G was published this year for comment and is expected to achieve final publication by year end, 2015. DO-160 G Section 22 has been incorporated, in part, into MIL STD 461G, newly created section CS117. The presentation reviews all added requirements to CS117, and a brief history of the DO-160 Section 22 requirements.
Paul Zdanowicz - Fair-Rite The presentation discusses specifying and choosing ferrite components for EMI suppression. Topics include the basic operation of ferrite material and a review of ferrite applications with an in depth discussion of EMI Suppression. Also covered are intrinsic material characteristics, factors affecting core selection, choosing a material based upon frequency of operation, and environmental & bias conditions - all with the goal of narrowing the options when choosing a ferrite solution.
Rick Taylor and Jason Pedruzzi - Filconn Filter connectors are generally perceived to be one of life’s necessary evils, and while they are expensive, there are ways to get extra value from the filter connector as it is designed into the system. Also discussed will be the pros and cons of transient suppression using diodes or MOVs.
Jeff Davis and Timothy Liu - TennMax The presentation contains information useful for current users of metal cans or multi cavity metal housings on PCBs. Technologies discussed include; Robotically dispensed conductive gasket (Form in Place), Metallizing plastic via Physical Vapor Deposition and Conductive polymers. For optimal size, form-factor and weight, combination design approaches using metal/metalized plastic/FIP and conductive polymers are also covered.
David Stanis - WEMS Electronics The talk addresses the various types of industry-wide custom EMI filters both single-circuit components and multi-circuit filter assemblies. Discussion includes common-mode and differential-mode interference and filtering techniques, MIL-PRF-28861 “S” Level requirements and problems. A review of EMI Filter Source Control and Specification Control Drawings is also provided.
Paul Zdanowicz - Fair-Rite The presentation contains information useful to specify and choose ferrite components for EMI suppression. Topics covered are the basic operation of ferrite material with an in-depth discussion of EMI Suppression. The discussion includes Intrinsic Material Characteristics, factors affecting core selection, how to choose a material based upon frequency of operation, and environmental and bias conditions.
Marcin Szajner - Würth Elektronik The presentation covers advanced EMC topics including magnetics, attenuation, coupling modes, emissions and transformers.
Tom Mullineaux - Milmega 4th Generation (4G) cell phones are now available on the open market providing the high data-rate exchanges required for video streaming. Faster data rates while maintaining a modest channel bandwidth inevitably means more complex digital modulation techniques. Product standards may stipulate test bands that cover the frequency bands of the threats, however the analog modulated test signal is comparatively benign and does not ensure product RF immunity to these omnipresent signals. The talk includes classification of current threats; prevalence and nature of 2G, 2.5G, 3G and 4G signals; the time/event when the threat greatest; complex waveform peak to average ratios; amplifier power back-off required for test signal integrity; near-field/far-field interference, and simulating the threats in an ALSE or GTEM Cell.
Bruce R. Lane - Jerrik The presentation discusses approaches to incorporation of TVS diodes in connectors, with a focus on TVS in lightning protection.
Jason Koshy- Transtector/PolyPhaser This presentation is geared toward understanding EMP (Electromagnetic Pulse) threats and how to mitigate these events. HEMP (High altitude EMP), SREMP (Surface generated EMP), Solar Flairs, EMP, EMI (Electromagnetic Interference) and transient (lightning and manmade surges) are covered. This presentation discusses how these events are generated, related industry standards, and how to protect a critical system from these events.
Don Heirman - ASC Commercial EMC standards have been around for decades. They are produced by many committees such as those in the International Electrotechnical Commission (IEC), the European Telecommunications Standards Institute (ETSI), the IEEE EMC Society, and more close to home the American National Standards Institute (ANSI) accredited standards committee. The US Federal Communications Commission references in their Rules several ANSI ASC C63® standards such as the omnipresent ANSI C63.4 on product emission testing, C63.19 on Hearing ad EMC compatibility, and C63.17 on unlicensed Personal Communications Services (UPCS). Hence while such standards are voluntary, when they are specified by the FCC (or even a user), they become mandatory. This talk reviews the standards activity of C63® showing what are the “hot” topics and the extent of the work and when they might be published. Among those highlighted will be the work on test site validation, transmitter compliance testing, and others.
Douglas A. Toth - Wurth Electronics The types of Electromagnetic interference over various frequency ranges and their classification are covered, including conducted differential mode interference, common mode interference and radiated interference. Recommendations and examples for lowering these types of interference are presented. Basic information about materials such as loss characteristics, frequency of operation and inductive properties are also part of the presentation.
Robert Emerson - Zes Zimmer This presentation looks at the changing landscape of international standards governing harmonic currents and voltage fluctuations (flicker) on the low voltage alternating current public mains networks, and the ensuing impact on product design and test for low and medium power applications. Highlighted is the impact resulting from changes to international standards for harmonic limits EN/IEC 61000-3-2 and EN/IEC 61000-3-12 and flicker limits EN/IEC 61000-3-3.
Praveen Pothapragada - Equipto Electronics Corporation This presentation discusses the current vulnerability of our data centers and electronics packaging methods. Included are tradeoffs considered for mechanical flange designs, RF absorptive materials, RoHS, and material selection. In addition, the EMC test results and test plan are also presented. Finally, the implications of these approaches with other types of electronics enclosures under varying environmental requirements (seismic, military level shock/vibe) are presented.
Douglas A. Toth - Wurth Electronics Midcom An Introduction to the EMI applications of PCB Layout, Common & Differential Mode Filtering and the use of Shielded and Unshielded Inductors. In addition, the selection of various core materials for transformers and inductors are discussed.
Walter A. Poggi - Retlif Testing Laboratories The presentation focuses on the growing awareness for the need of Electromagnetic Compatibility in today’s evolving rail and transit industry. The transition from an electromechanical “world” to a microprocessor one will be reviewed as well as look at the growing technologies of Positive Train Control and Communications-Based Train Control. Reviewed in the presentation are the building blocks of current EMC compliance programs used by agencies such as the New York City Transit as well as an overview of the normal EMC testing requirements imposed on today’s rail and transit equipment.
Jason H. Smith - AR Worldwide A discussion of the changes that have been made to the IEC 61000-4-3 Edition 3 standard which include: Higher frequency range, more clearly defined field and setup requirements. A discussion of the present work being done in Working Group 10 on IEC 61000-4-6 and IEC 61000-4-3, and review the basic process and timing of revisions and standards development within the IEC.
Mike Hertz - LeCroy Corporation Techniques for measuring electrostatic discharge, electromagnetic coupling, and fast transient pulses are described, using custom measurements and thresholds. Measurement filters, segmented acquisitions, enhanced pulse parameter definitions, and other techniques are applied. A measurement integrity comparison using standard measurement techniques vs. EMC-specific measurement techniques is shown.
Thomas Mullineaux - MILMEGA The technical and practical aspects of testing over 1-10GHz with either multiple high-gain horn antennas, or with a single medium-gain horn antenna are reviewed. The compound frequency effect of cable-loss/antenna-gain is introduced as is the effect of antenna gain on test illumination area.
Richard J. Mohr - R J Mohr Associates In the discipline of electromagnetic compatibility (EMC), electromagnetic shields can be considered as the top level of control of electromagnetic interference (EMI). This lecture reviews the basics of the plane electromagnetic shield as approached by Schelkunoff. He treated shielding analysis by analogy to transmission line analysis. He modeled the shield as a section of lossy transmission line, and then reduced the associated transmission line equations to characterize the shield in terms of factors for its reflection loss and absorption loss, and an additional factor to correct for multiple reflections within the shield. His model has served as the starting point for nearly all subsequent work in shielding analysis. He first derived his model from conventional transmission line equations; then he derived the same model by considerations of multiple reflections. The latter approach provides solid insight into the shielding parameters, and particularly to the important correction factor.
Jim Skelly - Cybershield The presentation reviews plastic resins that can be coated, processes used to metallize plastics, and metals that can be applied onto plastics. There is an examination of mechanical design guidelines for metallized plastic parts for the various coating processes. Coating performance, including resistivity and shielding effectiveness is discussed, as is conductive coating quality metrics (adhesion, metal coating thickness, and resistivity) and how they are measured to ensure compliance with customer specifications. There is also an analysis of the process, design guidelines, plastic resins and application of precision 3D circuits onto plastics. A number of commercial applications using metallized plastics are reviewed. Finally, metallized plastics and the impact of RoHS (Reduction of Hazardous Substances) and WEEE (Waste from Electrical and Electronic Equipment) is assessed.
Richard Mohr – RJ
Mohr Associates This lecture covers the “why and how” practices to minimize crosstalk in wiring and cabling. Optimum shielding and grounding practices are outlined. Common pitfalls are highlighted, and corrective measures shown. Concise models remove the mystery and “black magic” in wiring and cabling, and allow for accurate prediction of crosstalk.
Peter A. Blais - Kemet The technical advancements made with Ceramic MLCC, Tantalum-MnO2, Tantalum-Polymer and Aluminum-Polymer capacitor technologies are discussed. In addition, these devices are compared in terms of frequency response, de-rating and lead-free process capability.
Carl Lindquist - San-O Industrial Those responsible for designing circuits using overcurrent protectors, as well as those purchasing such protectors, often misinterpret specified parameters and “equivalent” devices when seeking primary and secondary sources. This presentation provides a brief overview of various types of overcurrent protectors, including fuses, PTCs, circuit breakers, etc. The discussion concentrates on fuse design, the relative strengths and weaknesses of different types of fuse designs, important protector parameters and documentation recommendations.
Harry Fuerhaupter - Potter Industries Galvanic corrosion can be a significant concern for product designers in EMI shielding applications. The mechanism behind galvanic corrosion and the selection of shielding materials that will minimize this effect, are discussed. Also, a new conductive filler for elastomer EMI gaskets is presented. The new filler exhibits very low galvanic corrosion while providing excellent shielding.
Ed Hare - American Radio Relay League The basic concepts of Broadband Over Power Lines (BPL) are reviewed, along with its potential impact on HF communications. ARRL efforts to protect the interests of amateur radio are also discussed. The lecture summarizes studies, including field trips to BPL trial areas, and testing performed by ARRL, and the League's work in the standards arena.
Doug McKinnon - Emscan Corporation Electromagnetic scanning improves designer productivity, while reducing costs and time-to-market. This lecture describes how electromagnetic scanning plays a vital role in pre-compliance testing and in sustaining operations. Near-field and far-field relationships are discussed, along with the value of combining electromagnetic scanning, cable measurements and chamber results. Applications such as immunity (susceptibility) testing, evaluation of filters and shields, and finding the sources of radiation will be addressed.
Gary Fenical - Laird Technologies Advances in electronic equipment are occurring at a rapid pace. The wireless revolution, increasing power levels in computers and servers, higher frequency systems, decreasing size of cell phones, to name a few. To keep pace with the EMI shielding needs of these devices, a wide range of new and improved products have been developed over the past few years and many more are on the drawing boards. Just about every class of shielding product has seen noteworthy changes. The uses, properties, and advantages of these new materials and advanced EMI shielding product designs are described.
Dave Arthurs - Spectrum Control The lecture covers the types of EMI filters, propagation modes and methods of suppression. Basic circuits of Low Pass filters are explored as well as their impact on timing and I/O impedance selection criteria. In addition, applicable EMC specifications are also presented. The lecture is intended for individuals involved with EMC design and/or EMC testing/troubleshooting.
Paul Zdanowicz - Fair-Rite Products The presentation discusses the specification and selection of ferrite components for EMI suppression. Topics covered include the basic operation of ferrite material, their operation in reducing EMI and the significance of test methods.
Terry Mahn - Fish and Richardson Legal issues involving domestic and international product standards development, harmonization, and compliance in the areas of EMC, electrical safety, RF emissions, telephony, and RF safety. FCC issues including all facets of spectrum allocation, wireless technology authorization, and licensing equipment approvals.
>
Viewgraphs
(0.4 MB)
This is a broad topic and covers various aspects of the Accreditation, Certification, and Endorsement processes that EMC and TEMPEST Engineers must contend with. This presentation is carried out by three members of the Long Island IEEE EMC Chapter who, along with their businesses, collectively possess the laboratory and personnel credentials to be discussed, and programs and processes needed to obtain them.
>
Viewgraphs, Laboratory Accreditation (0.2 MB)
EMI attenuation options have progressed well beyond discrete solutions. This talk centers upon the integration of filters within passive components. The impact of these fixes upon system design is discussed, and next generation passive components are outlined. Areas of discussion will include: the integration of LC-T configuration filters into a ceramic chip (0805 and 1206 sizes); the integration of LC-T filters with MOVs to form active LC-T filters in 0805 and 1206 array packages; reduction/control of parasitic parameters (ESL/ESR) within capacitors - impact upon signal integrity; and, the next generation Ball Grid Array Passive Components. > Viewgraphs will not be posted
There is no question that there is an overlap of technologies and skills between EMC testing and RF safety analysis. In some cases, even the same measurement equipment is used. But while EMC testing involves testing in accordance with very specific guidelines, RF safety analysis is far less disciplined. There are many reasons for this, including a lack of consensus of what constitutes "safe" or compliant versus "unsafe" or noncompliant. It all starts with understanding of how the biology has driven the standards and regulations. It also involves the work environment and both administrative and engineering controls that can be used to reduce the possibility of somebody being hurt. Topics will include: sources of potentially unsafe levels of RF energy; basic biology and an overview of standards and regulations; measurement equipment; and the elements of a good RF safety survey.
Virtually every electronic device or system designed today needs to comply with EMI/EMC standards. Proper EMI/EMC design, throughout the development cycle, is necessary to cost-effectively ensure that products operate reliably in their intended electromagnetic environment without being susceptible to electrical noise from other devices, or generate excessive noise that can interfere with other devices. Meeting this goal has become especially challenging in recent years, due to the ever-growing use of electronics, increasing clock frequencies and escalading wireless-bandwidth demands. The presentation will review basic EMI/EMC definitions, and summarize some of the applicable standards (EU, MIL, FCC, RTCA, etc.). Following will be a discussion on radiated emission/susceptibility control and conducted emission/susceptibility control, and their impact on electrical/mechanical design. Topics covered will include signal spectra, enclosure/cabling design, PWB design, and signal/power distribution. EMI/EMC design process will also be discussed.
>
Viewgraphs, Revision 3 (1.8 MB)
All of us have witnessed, and many have been awed by, the pure power of Mother Nature's fury during thunderstorms. While we may marvel at lightning from a distance, too close of a call can be frightening and downright dangerous. The aircraft industry also must respect lightning strikes. With electrical currents of upwards of 200,000 amperes generated during severe cloud-to-ground strikes, aircraft, which intercept or trigger the lightning channel, must be able to fly through it with minimal structural damage and minimal loss/upset of on-board avionics, flight controls, and electrical systems. Discussion will center on the lightning environment, the effects of lightning on structure and coupling mechanisms for equipment, commercial and military design/test requirements, protection design scenarios and techniques, and certification/qualification plans, test methods, and procedures.
EMI, EMP, ESD, lightning, and similar design/test requirements are typically imposed on most military and commercial electronic equipment built today. EMI filter connectors are a viable option when equipments must operate in such adverse environments. Improvements in technology have allowed EMI filter connectors to migrate from a design fix that was implemented as an "afterthought" to a design solution, that is planned for at the beginning of the equipment design process. Improvements have not been limited to filter technology. Available design tools allow the user of filter connectors to more easily select the correct part and ensure that these parts will survive required surge, lightning, and ESD levels. The use of present-day filter connectors for common and differential mode suppression in RF and transient environments, will be presented. In addition, technical descriptions of pSpice models, surge analysis tools and details of currently available product lines will also be presented.
>
Viewgraphs - Part 1 (0.7 MB)
After much debate and long delay, the EU required that harmonic and flicker testing be included in the suite of EMC requirements for all CE marked electronic products sold on, or after, January 1, 2001. Testing for harmonic content is specified in IEC61000-3-2, and testing for flicker is specified in IEC61000-3-3. Amendment A14 of IEC61000-3-2 was issued to simplify the harmonics testing, but it added some new requirements in the process. The end result has been an increase in testing criteria needed for CE marking. Amendment A14 also added quot;interharmonic grouping tests," and these will be required beginning in August of 2005. This expansion means that the manufacturer, and EMC Engineer have to be aware of the effects that harmonics from other sources have on products being developed and sold.
The new EN60601-1-2, 2001 Standard contains the new set of EMC requirements for medical equipment to be sold in the EU and is also recognized by the FDA. This standard covers not only the requirements but also documentation that needs to accompany products to market. We will discuss the differences to the existing standards and show how the newer document has aligned itself to other international requirements.
Interest in electromagnetic life above 100 MHz has increased in the past decade, primarily due to an increase in high speed digital electronics and telecommunications. In this frequency regime, many of the usual simplifying assumptions are no longer true and the EMC engineer must adopt a new way of looking at the problems.
An intuitive approach allows the engineer to visualize the system as a collection of components whose characteristics can be estimated, or if necessary, measured. Effects, such as parasitic effects, absorption, radiation losses and wavelength effects become more significant above 100 MHz, but are reasonably well understood. |
|||
|
|
|
||
2024 Chair
2024 Vice Chair
GaN FET-Based CCM Totem-Pole Bridgeless PFC
Lou Diana - Texas Instruments