In Compliance: The Compliance Information Resource for Electrical Engineers logo
NASA Space Shuttle’s Return to Flight
The Untold Electromagnetic Backstory
Reducing Battery Life Risk in Mission Critical IoT Devices

Common Mode Filter Design Guide

Health Monitoring and Prediction of Cells in a Battery Module or Pack Under Operating Condition

rocket launch at sunset
Reducing Battery Life Risk in Mission Critical IoT Devices

Common Mode Filter Design Guide

Health Monitoring and Prediction of Cells in a Battery Module or Pack Under Operating Condition

August 2022
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August 2022
Volume 14 l Number 8
The Untold Electromagnetic Backstory
By Brian M. Kent
The 2003 Columbia re-entry accident was caused by a piece of liberated external tank foam that struck and damaged the left leading edge during powered ascent. Computational and experimental electromagnetics were ultimately applied to foster the development of a new NASA Ascent Debris Radar (NDR) for the remaining 22 Shuttle missions. In the process, countless static and dynamic radar signature and EMI/EMC calculations and tests were completed to assure this safety-critical radar system was ready for the return to flight (RTF) missions.
By Brad Jolly
The Internet of Things (IoT) is moving into more mission critical applications, especially with connected medical devices. Engineers can reduce the risk of premature battery failure by following the practical methods described in this article.
By Leonard Crane
The selection of component values for common mode filters need not be a difficult and confusing process. The use of standard filter alignments can be utilized to achieve a relatively simple and straightforward design process, though such alignments may readily be modified to utilize pre-defined component values.
By Michelle Kuykendal, Daniel Kingsley, and Ashish Arora
Tin whiskers are small, hair-like structures that can form naturally from the surface of tin components. This article explores potential contributors to tin whisker growth, failure mechanisms that may be induced by whiskers, current testing standards and processes, and mitigation strategies, with a particular focus on the automotive industry.
rocket launch
row of batteries and one with a pulse on it
Common Mode Filter
tin whisker layout of a car
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EMC Concepts Explained
Bogdan Adamczyk
Troubleshooting EMI Like a Pro
Min Zhang

Hot Topics in ESD
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compliance news

Amateur Radio Operator Fined for Interfering with Fire Suppression Communications

The U.S. Federal Communications Commission (FCC) has proposed a record fine against an amateur radio operator for interfering with radio communications supporting fire suppression efforts in a 2021 massive wildfire in an Idaho national forest…
EU Commission Seeks to Expand Scope of REACH
The Commission of the European Union (EU) is reportedly seeking to expand the provisions of the EU’s chemical restriction regulations to include the use of lead and lead compounds in polyvinyl chloride (PVC) polymers and copolymers…
DILBERT comic strip
DILBERT © 2022 Scott Adams. Used By permission of ANDREWS MCMEEL SYNDICATION. All rights reserved.
Feature Article
NASA Space Shuttle’s Return to Flight:
The Untold Electromagnetic Backstory
How Applied Electromagnetics Guided the 22 Post-Columbia Shuttle Missions
by Brian M. Kent
NASA rocket
Editor’s Note: This article was originally published in the June 2019 issue of  In Compliance Magazine. We are pleased to reprint Brian Kent’s article in honor of his keynote presentation at this year’s EMC + SIPI Conference, to be held in Spokane, Washington, August 1-5.
With deepest respect, this article is dedicated to the extended families and friends of the astronauts lost on Columbia’s final Shuttle mission.

n February 1, 2003, NASA’s Space Shuttle Orbiter Columbia broke apart upon re-entry into the earth’s atmosphere, tragically ending the lives of seven highly-trained and experienced astronauts. This accident not only personally affected the extended families of the astronauts, it permanently changed the trajectory of the U.S. manned space program. After a lengthy accident investigation and root cause analysis, the Shuttle successfully flew again on July 26, 2005. The Shuttle’s subsequent 22 missions made possible the completion of the assembly of the International Space Station (ISS) and provided a final service call for the Hubble Space Telescope, before the Shuttle fleet was retired in 2011.

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Feature Article
Reducing Battery Life Risk in Mission Critical IoT Devices
How Artificial Intelligence (AI) and Battery Emulation Can Help Reduce Risk
By Brad Jolly
row of batteries and one with a pulse on it

he Internet of Things (IoT) is quickly being adopted for use in mission-critical applications for several reasons. First, the IoT now incorporates increasingly sophisticated technologies, such as artificial intelligence (AI), augmented reality, edge computing, sensor fusion, and mesh networking to tackle problems of increasing difficulty and importance. Second, as recent supply chain challenges have demonstrated, margins for error and delay are slim at best. Third, the demand for increased healthcare, combined with resource scarcity, means many medical services must decrease in cost and become more efficient. Finally, the desire to conserve resources means devices must last longer and perform more reliably.

These trends present numerous business opportunities in fields that serve human health, safety, food production, environmental protection, and other key aspects of human flourishing. As technical challenges grow, each of the 5 Cs + 1 C of the IoT becomes more important. Some of these can use artificial intelligence (AI) as part of the solution.

Feature Article
Common Mode Filter Design Guide
By Leonard Crane
A common mode filter

he selection of component values for common mode filters need not be a difficult and confusing process. The use of standard filter alignments can be utilized to achieve a relatively simple and straightforward design process, though such alignments may readily be modified to utilize pre-defined component values.


Line filters prevent excessive noise from being conducted between electronic equipment and the AC line. Generally, the emphasis is on protecting the AC line. Figure 1 shows the use of a common mode filter between the AC line (via impedance matching circuitry) and a (noisy) power converter. The direction of common mode noise (noise on both lines occurring simultaneously referred to as earth ground) is from the load and into the filter, where the noise common to both lines becomes sufficiently attenuated. The resulting common mode output of the filter onto the AC line (via impedance matching circuitry) is then negligible.

Feature Article
The Impact of Tin Whisker Formation on Vehicle Electronics
By Michelle Kuykendal, Daniel Kingsley, and Ashish Arora
Illustration of a car
Editor’s Note: The paper on which this article is based was originally presented at the 2019 IEEE International Symposium on Product Safety Engineering held in San Jose, CA in May 2019. It is reprinted here with the gracious permission of the IEEE. Copyright 2019, IEEE.

Tin whiskers are small, typically hair-like structures that can form naturally from the surface of tin components in electronic devices (Figure 1). Tin whisker formation is a well-documented phenomenon that has been studied for decades. Throughout this time, little consensus has been reached regarding the particular mechanisms behind tin whisker formation. Whisker formation is believed to be a diffusion-controlled process motivated by stresses, both internal and external; however, the wide range of factors that may produce material stresses makes it exceedingly difficult to identify or isolate individual factors.

EMC concepts explained
Eye Diagram

Part 1: Fundamental Concepts

By Bogdan Adamczyk, Krzysztof Russa, and Nicholas Hare

his is the first of two articles devoted to an eye diagram. In this article, the fundamental definitions and concepts are presented. The next article will show the impact of driver, receiver, and interconnect properties on signal quality using data eye and data eye mask concepts while evaluating several different HDMI cables.

Consider a digital signal as it travels from a transmitter to a receiver. The quality of the signal arriving at the receiver can be affected by many factors, including the transmitter, cables or PCB traces, and connectors. The signal quality is also referred to as signal integrity. An eye diagram is a graphical tool used to quickly evaluate the quality of a digital signal. The name eye diagram has been coined because it has the appearance of a human eye [1,2]. Eye diagrams are commonly used for testing at both receivers and transmitters.

An eye diagram is basically an infinite persisted overlay of all bits captured by an oscilloscope to show when bits are valid. This provides a composite picture of the overall quality of a system’s physical layer characteristics. This picture covers all possible combinations of variations affecting the signal: amplitude, timing uncertainties, and infrequent signal anomalies.

hot topics in ESD
Challenges of Designing System-Level ESD Protection at the IC-Level:

Misconceptions Regarding Current Flow to the IC

By Hans Kunz for EOS/ESD Association, Inc.

here is often confusion about the interaction between IC-level component ESD protection and the appropriately required system-level ESD protection strategy. System-level ESD requirements (like IEC 61000-4-2 [1] and ISO 10605 [2]) are intended for electronic systems, not for individual integrated circuits (ICs). However, it is becoming increasingly common to see supplier claims and customer expectations of system-level ESD performance at the IC-level. While such performance may be desirous to both suppliers and customers, there is significant ambiguity about what such claims and expectations mean. Generally, little information is available about the actual system surrounding the IC. How does the customer interpret an IC-level performance claim without a specific system, and how does a supplier design for and guarantee performance? Certainly, the IC has been tested in some systems to facilitate the datasheet specification, but how did the designer define that system, and how does it compare to the final customer system? This lack of specificity implies that a general capability of the IC applies to a wide range of unique system requirements when, in fact, there are significant challenges to integrating an IC into a single unique system. These challenges extend beyond safely conducting the current during the ESD event—systems are often powered, and the failure criteria can include functional operation during and after the ESD event. But gaps exist that must be considered even if the problem is reduced to a simple guarantee that current can be safely conducted during the ESD event.

troubleshooting EMI like a pro
Cable Antennas and Ferrite Cores
By Dr. Min Zhang

esign engineers who have been to an EMC testing laboratory must be familiar with the large selection of ferrite cores that a test lab often provides. For a product with a mains lead or a system consisting of long cables (HDMI, USB, etc.), the most common EMC failures often include conducted emissions in the frequency range of 9 kHz and 30 MHz and radiated emissions in the 30-300 MHz range. In such cases, cables often become effective antennas, and ferrite cores are generally used to locate and suppress the noise (at least during the troubleshooting stage).

The practice of using ferrite cores on cables is often performed using a trial-and-error approach. Engineers place a ferrite core on one end of a cable and measure the performance. If the noise at the frequency range of interest is reduced with the placement of the ferrite core, this means the approach works. If not, the ferrite core is then removed and placed in another cable.

In this column, I offer a brief summary of a more systematic approach for using ferrite cores on cables. Hopefully, this summary can serve as a “ferrite core checklist” for design and test engineers.

Upcoming Events
August 1-5

September 5-8
EMC Europe 2022

September 13-15
The Battery Show

September 13-15
Fundamentals of Random Vibration and Shock Testing Training

September 13-16
Lab Techniques, Robust Design, and Troubleshooting

September 18-23
44th Annual EOS/ESD Symposium

September 20-22
ISPCE 2022

September 29
2022 Minnesota EMC Event

October 6-7
Fundamental Principles of Electromagnetic Compatibility and Signal Integrity

October 9-14
AMTA 2022

October 17-20
Military Standard 810 (MIL-STD 810) Training

October 18
2022 San Diego Test Equipment Symposium

Due to COVID-19 concerns, events may be postponed. Please check the event website for current information.

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