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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.

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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