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Power Supply Safety and Compliance

This section presents articles on Safety & Compliance relevant to both designers and users of power supply products. These articles discuss compliance requirements related to safety, electromagnetic compliance (EMC), energy efficiency, and other areas affecting power supply approvals regionally and globally for diverse applications and markets. The articles discuss compliance issues from the design stage through pre-compliance and final compliance testing. Some articles are deeply technical, others relate case studies involving power supply customers. These article were previously published in the Spotlight on Safety & Compliance column of the How2Power Today newsletter, which is sponsored by Power Integrations. These articles were authored by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee. Bios of these authors are also presented here. This section also presents some other safety and compliance related resources.

Maintaining Battery Safety And Life Of Battery Are Top Priorities In Battery Charger Design

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

Over the years, various rechargeable battery chemistries have been developed including sealed lead acid (SLA), NiCd, NiMH, Li-ion, Li-ion polymer and lithium iron phosphate (LFP or LiFePO4). All of the rechargeable chemistries have advantages and disadvantages, but they’ve all had safety issues related to charging. In this article, we’ll discuss the risks to battery safety and long operating life posed by charging errors, and describe the techniques used in charger design to prevent these errors. We’ll also identify some of the governing standards. This information may be of value both to those designing battery chargers as well as those who are specifying battery charger products. Read the full article…

Selecting An AC Line Filter For Switching Power Supply Applications

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

While guidelines have been written on how to select EMI line filters, many system engineers still aren’t aware that they need EMI filters. When they do realize they need one, they often select a filter without regard to their actual filtering needs. They may also ignore the impact of the filter on other requirements (such as leakage current), and issues such as customer support. In this article, the authors identify some of the popular bad practices being used to choose EMI line filters, explain why they’re wrong and provide a quick guide to proper filter selection that will help designers avoid the common pitfalls. They identify the key criteria you’ll need for filter selection including rules of thumb and key specs that will guide designers in making good choices. Armed with this information, designers will be better equipped to apply the EMI selection guides and tools already available. Read the full article…

Explaining The ROI Of Compliance Efforts To Your Colleagues

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

In this column, we frequently stress the need to plan for compliance requirements—all types including safety, EMC, energy efficiency and environmental/restricted materials—early in the product design cycle or process. We stress the need to know the requirements and to perform pre-compliance testing as you go through the different design stages. But knowing we should do these things, and getting our companies to agree to do them are different things. So often there is resistance from other members of a design team, or other colleagues in the organization, to take the necessary extra steps to ensure that compliance needs are considered throughout product development. How do we overcome this resistance? A paper presented at the recent IEEE EMC + SIPI 2019 conference provides guidance on how compliance advocates can convince their colleagues in engineering and management of the value, or more specifically, the return on investment (ROI) of addressing compliance needs early and throughout the product design process. Read the full article…

Will Your Products Be Ready For Next Wave Of European Efficiency Regulations?

by Arnold Alderman, Maintenance Leader PSMA SCDB and EEDB Data Bases

In a previous Spotlight on Safety & Compliance column, the author alerted designers and product planners that products sold in Europe would be required to have continuously higher efficiency to comply with 2020, 2030, and 2050 EU reduced energy consumption requirements as compared with the 2016 estimated EU power consumption level. The EU Commission created two framework directives: Ecodesign, and the corresponding Energy Labelling, which have driven efficiency improvement in the appliance category products over the past two decades. Resulting product efficiencies have increased by 40% in some cases. Read the full article…

Forms Vs. Function: Battling The Paperwork Deluge On Restricted Substances

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

Almost once a week or more the phone rings or an email arrives, usually from a top name brand company or on behalf of one, asking about our product’s compliance with environmental and hazardous materials regulations. I [Kevin] work for a semiconductor manufacturer, so the requests concern components we’re supplying to a customer. But anyone supplying any components, subassemblies or finished electronic instruments or equipment could be subject to such inquiries. The request comes from a far off land because it’s been outsourced to someone to get a form filled out. The good news is that people are paying attention to restricted materials regulations. However the bad news is that many customers are inflexible in the way they work with their suppliers to gather the needed information. In this article, the authors describe the problem, suggest some possible solutions, and point to some helpful resources. Read the full article…

Measuring Common-Mode And Differential-Mode EMI Currents

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

Line-conducted EMI current is composed of two elements: common mode (CM) current and differential mode (DM) current. Either one of these contributors to line-conducted EMI may be responsible for a unit failing EMC testing. And without knowing why a unit is failing, coming up with a solution can become a time-confusing exercise in trial and error. On the other hand, by measuring CM and DM EMI currents separately, engineers can identify why their products are exceeding the specified EMI limits and quickly tailor an EMI filter solution to pass EMC testing. Although the techniques for measuring CM and DM currents are well documented in the literature, many power supply engineers are still unfamiliar with them and therefore do not make these measurements. In this article, the authors review the literature regarding measurement of CM and DM EMI currents, offer an overview of the different measurement techniques and point to the references where readers can delve more into the details of making the measurements. Read the full article…

An Introduction To Medical Regulations: Understanding The 60601 Standard

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

This article aims to give an initial introduction to the rules and regulations that govern safety and compliance in medical equipment. This basic information does not go into details of medical power supplies. Rather, an attempt is made to enlighten those not familiar with the medical regulations and standards, including designers and specifiers of medical power supplies. In particular, we aim to shed light on the importance of medical equipment immunity from radiated and conducted electromagnetic emissions. Medical regulations are complex because they apply to the safety of both patients and medical practitioners. The 60601 standard, which is the focus here, applies to most locations throughout the world, and anywhere medical equipment is used: operating rooms, hospital rooms, intensive care units, nurseries, senior care facilities and even households. Read the full article…

Pre-Compliance Testing Is Necessary For All Products

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

For some companies, pre-compliance testing may seem like a source of unnecessary expense or extra steps in an already time-constrained product development schedule. Or it may be something they’ve given no thought to at all. But when the risks associated with not performing pre-compliance testing are considered, it becomes clear that pre-compliance testing is a means of avoiding unwanted increases in product development cost. Pre-compliance testing alerts the design, engineering management and marketing teams that an issue may be lurking in the weeds and informs them of the potential problem before the product ships. By applying pre-compliance testing prior to production, excessive redesign costs, and production delays can be avoided. Read the full article…

Knowing The Link Between Product Regulations And Product Standards Can Put You Ahead Of The Competition

By Arnold Alderman, Maintenance Leader PSMA SCDB and EEDB Data Bases

A regulation is a rule or directive created and maintained by an authority such as a country, federation of countries, states, or provinces. Enforcement is by law. Content is available to the public for free. A standard is a document created by consensus and approved by a recognized body or organization for common or repeated use. Standards may be international or regional. Most standards are available to the public for a fee levied by the organization. Enforcement occurs when a label is attached to the product indicating compliance. Regulations precede and influence certain performance and test standards. This article explains how company standards staff and design engineers can monitor and influence a regulation far in advance of any standard(s) creation thus better positioning their company products for success under the new regulation. Beginning with an historical example, the author chose the European Union (EU) and the relationship between the Ecodesign efficiency regulation and the relevant IEC standard(s). Read the full article…

Materials Compliance: Just as Critical As Electrical Safety & EMC

By Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

For most power electronics engineers, and perhaps for hardware designers in general, environmental regulations have not been high on the list of design considerations. Other compliance requirements have usually demanded more attention. But that situation may be changing and now even power supply designers may need an awareness of the regulations governing restricted materials. According to one expert who spoke at a recent webinar on materials compliance in electronics, in terms of recall issues, materials compliance deserves the same priority as electrical safety and even more than EMC. The materials compliance area is expanding in scope and the repercussions of not meeting the standards are higher than ever before as the authors explain. Read the full story…

Roadmap Charts Compliance Trends And Requirements For Power Supplies

By Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

The Power Sources Manufacturers Association (PSMA) devotes a section of its Power Technology Roadmap (PTR) to reporting on relevant trends in power supply safety and compliance. For those unfamiliar with the PTR, it is a document published every two years “to provide a consolidated outlook of trends in power conversion technology for the next two to five years.” In the latest version of the roadmap, PTR 2019, which is due to be released at APEC, the section on Safety & Compliance describes how power supply compliance has become more challenging since the last PTR was published. Although certain requirements such as those for safety and EMC, have always been in conflict, it has become harder to strike the necessary balance in power supply development as both the safety and the EMC requirements become more stringent. There are also more stringent environmental requirements coming from RoHS, WEEE and conflict material legislation. Read the full story…

Proper Design Of The Power Supply’s Input EMI Filter Protects Against Power Line Transients

By Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

In this article, author James Spangler examines the standards that address a power supply’s ability to withstand ac power line transients including those induced by lightning. He shares the results of his research on what standards apply and how they were developed. He then discusses the role that the EMI filter stage plays in providing protection against power line transients and how designers can determine whether changes or additions to this protection are required to meet the applications’ requirements. Read the full story…

Very Down To Earth Treatment Of Grounding For Power Electronics Designers

Grounding and Bonding for the Radio Amateur, published by The American Radio Relay League (ARRL), copyright 2017, 176 pages, available in softcover or Kindle edition, ISBN number 978-1-62595-065-9, item number 0659, $22.95 from ARRL.

Reviewed by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

When the subject of ground comes up in power supply design, it’s usually in the context of circuit design or measurement, and the discussion often concerns noise issues in some way. How to layout ground traces and planes to avoid crosstalk, EMI, groundbounce and similar effects. But there’s another side to ground that concerns the safety of equipment, and more importantly, the safety of its operators. This is where the related subjects of grounding and bonding come in, and these are the focus of the book being reviewed here. They’re important because safety, lightning protection, emissions–immunity EMI-EMC and proper system operation overall will depend on how well grounding is done. Read the full story…

Low-Wattage Energy Efficient Power Supplies Got Their Start In White Goods

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

This article recaps how the process for developing energy efficient low-wattage power supplies began with the energy systems used in refrigerators back in the 1970s. Besides giving some insight into how low-power energy efficient power supplies developed, this article will help to explain how appliances became energy efficient. It also discusses why there are no efficiency standards specifically for the power supplies used in white goods. Read the full story…

Isolation Standards Say Little About Isolator Performance

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

There is confusion concerning which standards apply to the various types of optocouplers, optodrivers, and isolators used in gate drive and power supply circuits. There is also a general misconception that isolation standards set requirements for isolator performance beyond the input-to-output voltage isolation. In this article, the authors review the different isolator device types, identify some of the major isolation standards, and then discuss the requirements imposed on the different isolator device types. Read the full story…

EMC Wisdom Has A Long Shelf Life

EDN Designers Guide to Electromagnetic Compatibility, Daryl Gerke, PE, and William Kimmel, PE, available in PDF or hardcopy reprint from Kimmel Gerke Associates.

Reviewed by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

Back in the ‘90s when Kevin was working at Motorola, his company often provided in-house training for customers to help them get their systems working and into production. One of the works used in these courses was the EDN Designers Guide to Electromagnetic Compatibility, which was authored by two legends of EMC—Daryl Gerke PE and William Kimmel, PE of Kimmel Gerke Associates. In this review, Kevin explains why this book is still so valuable to system designers (especially power electronics designers) almost 25 years after its initial publication. Read the full story…

The DoE Views USB Chargers As External Power Supplies

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

The authors recently discovered that the USB-powered battery charger used by their cell phones and tablets is considered an external power supply (EPS), and not a battery charger under DoE rules. This became clear when reading the result of the appeals submitted to the DoE by a number of companies who charge the internal batteries using a USB Power Delivery system. This articles analyzes this ruling, discusses why USB chargers are viewed as EPSs, and what constitutes a battery charger under DoE regulations. Read the full story…

ISPCE 2018 Drilled Deeply Into Today’s Compliance Issues

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

In the vast world of conferences there are only a handful centric to the areas of safety and compliance as relevant to the electronics field. The annual IEEE Symposium on Product Compliance Engineering (ISPCE) is one of these events. In fact, for those with a stake in safety and compliance issues, it’s a must attend event. Kevin was among the approximately 250 participants at this year’s symposium in San Jose where ISPCE addressed all of the proximate issues in this field. Read the full story…

Beware The Pitfalls Of Power Suppy Hipot Testing

A dielectric withstanding voltage test—commonly referred to as a hipot test—determines the ability of equipment with an installed power supply to protect against electrical shock. However, for switching power supplies, the hipot test should be considered a destructive test. This article explains why that’s the case and how power supply users can avoid damaging power supplies through improper application of hipot tests. Read the full story…

Level VI DoE Rules And Regulations For External Power Supplies—Where To Find Them

The DoE energy efficiency standard currently in effect for external power supplies (EPSs) is known as Level VI. Although we have seen a number of articles stating the rules in some form, they do not provide a reference to where the rules are located and typically omit many details concerning their application. This article provides the URL where designers can actually find the Level VI energy efficiency rules with some discussion on related information. Read the full story…

New Isolation Technologies Close The Gap With Optos On Compliance

This year, the subject of isolation received special attention at APEC 2018 in two industry sessions and in a lively rap session where the merits of magnetic, capacitive and the incumbent optical isolation methods were debated. One of the key takeaways from these sessions was that alternative technologies are supplanting optocouplers in new designs. If you’ve not paid much attention to the new isolation technologies up until now, you might want to take another look. Read the full story…

PCB Board Layout Is Critical When The Power Supply And MCU Live On The Same Board

In many simple industrial and consumer products there is printed circuit board (PCB) that contains both a microcontroller (MCU) and a simple off-line power supply. In such cases, there are typically two sources of EMI: line conducted EMI from the power supply and radiated EMI from the MCU. When there is a failure in EMC testing, the customer’s first reaction is often to blame the power supply. But very likely, it is not the power supply causing the failure, but rather a poor PCB layout that caused the data lines to radiate. After reviewing some of the basic requirements of PCB design, we go step-by-step through the details of layout of a PCB for an MCU. Read the full story…

A Power Supply Can’t Fix All EMC Woes, Yet Partnering With The Right Power Supply Experts Early Can

Recently I was called by a customer who was failing EMC in the test lab. They were using one of our competitor’s power supplies and we had been talking with them about using ours. It was hard to ascertain if our pitch was falling on deaf ears or not. But now, with their product failing compliance testing, suddenly we were important to them as evidenced by them calling me after hours. With their product in the test lab there was real urgency as the money meter was running with the test lab charging them by the hour as the customer tried to get their product to pass EMC. This is their story and the lessons learned. Read the full story…

The Next Stage Of The Design Specification For Production: Energy Efficiency

This article is written to supply information on energy efficiency standards, which may be needed to complete the design of your product. Marketers and anyone who creates new product specifications need to review the energy efficiency specifications, before sending the document(s) to the engineering department. In this article, we introduce a specialized, free energy efficiency database that engineers can access to determine which energy efficiency requirements apply in their power supply or end equipment applications and also to keep up-to-date on changes in these requirements.  Read the full story…

Getting to Know IEC 62368-1—How Does A TV/Stereo Standard Affect My Industrial Power Electronics Design?

The prescriptive requirements of IEC 60950-1 intended for information technology equipment have existed for a long time. Independent of IEC 60950-1 is the IEC 60065 specification, which applies to audiovisual equipment, projectors, TVs and similar equipment. Now this is all changing as these two standards are being harmonized into a hazard-based specification known as IEC 62368-1. As with 60950-1 and 60065, the scope of 62368-1 includes internal and external power supplies. As the deadlines for transitioning to this new standard approach, power supply designers need to come up to speed on 62368-1 requirements.  Read the full story…

Understanding LISNs Is Essential To EMI Pre-Compliance Testing

A line impedance stabilization network (LISN) is a circuit used for testing power supply line conducted emissions produced by either a power supply or some other type of product that contains a power supply. Since there are multiple standards that require conducted emissions testing, if you are designing power supplies, chances are you’ll need to know enough about LISNs to perform pre-compliance testing of your product. In this column, the authors explain the basics of how LISNs work and are used, identify some of the applicable standards, and then analyze the differences between the LISNs specified by two FCC standards to help engineers understand when these differences affect testing and when they don’t.  Read the full story…

Power Supply Standards: Which Ones Apply In Your Application?

When an engineer begins a program, one confronting issue emerges—which standards or regulations must the product meet? The number of potentially applicable standards is quite large, covering a range of issues including safety, energy efficiency, electromagnetic compatibility, material toxicity and environmental considerations. In many instances, multiple standards apply, are sometime conflicting, and are often changing. These challenges motivated creation of the PSMA’s Safety and Compliance database. Here in this first Spotlight on Safety & Compliance Column, Kevin and Jim take readers on a tour of the database. Read the full story…

About the Authors of How2Power Today’s Spotlight on Safety & Compliance

Kevin ParmenterKevin Parmenter is an IEEE Senior Member and has over 20 years of experience in the electronics and semiconductor industry. Kevin is currently vice president of applications engineering in the U.S.A. for Excelsys, an Advanced Energy company. Previously, Kevin has served as director of Advanced Technical Marketing for Digital Power Products at Exar, and led global product applications engineering and new product definition for Freescale Semiconductors AMPD - Analog, Mixed Signal and Power Division. Prior to that, he worked for Fairchild Semiconductor in the Americas as senior director of field applications engineering and held various technical and management positions with increasing responsibility at ON Semiconductor and in the Motorola Semiconductor Products Sector. Kevin serves on the board of directors of the PSMA and was the general chair of APEC 2009. Kevin has also had design engineering experience in the medical electronics and military electronics fields. He holds a BSEE and BS in Business Administration, is a member of the IEEE, and holds an Amateur Extra class FCC license (KG5Q) as well as an FCC Commercial Radiotelephone License.

James SpanglerJames Spangler is a Life Member of the IEEE with over 40 years of electronics design experience and is president of Spangler Prototype Inc. (SPI). His power electronics engineering consulting firm’s priority is helping companies to place products into production, assisting them to pass government regulations and agency standards such as UL, FCC, ANSI, IES, and the IEC. 

For many years, he worked as a field applications engineer (FAE) for Motorola Semiconductor, On Semiconductor, Cirrus Logic, and Active Semiconductor, assisting customers in using semiconductors. He published numerous application notes and conference papers at a variety of conferences: APEC, ECCE, IAS, and PCIM. Topics included power factor correction, lighting, and automotive applications. As an FAE, he traveled internationally giving switch-mode power supply seminars in Australia, Hong Kong, Taiwan, Korea, Japan, Mexico, and Canada.

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