Webinar Test vs. Analysis - What's the Right Ratio? - This Thursday

PSMA (Power Sources Manufacturers Association) invites you and your colleagues to the February 18 PSMA Power Technology Roadmap Webinar "Test vs. Analysis - What is the Right Ratio for Achieving High Reliability?" Presenter: Charles Hymowitz, AEi Systems Inc. Register at #ptr #aei #reliability



Reliability is often a function of the amount of test and analysis applied. But programs are often budget and time constrained. So, what is the right ratio to achieve optimum reliability? Many industries lean on test, eschewing analysis as too expensive. For many programs, reference designs are employed without pessimism and no analysis is performed at all. This presentation discusses where can we focus our efforts to improve the reliability of high-reliability applications. How analysis compliments test and has changed over time, existing and emerging standards, BOL vs EOL tolerance impacts, methods for performing WCCA efficiently on new technologies, how to properly perform and interpret Monte Carlo analysis, and what circuit characteristics often fail stress and WCCA are discussed.




  1. We know very little about the parts we use - Parts are often like a box of Crackerjacks, there's a surprise lurking in each one and you don't know what it is until you open the box and find it.
  2. Most SPICE models provided by vendors are undocumented, uncorrelated to test data, inaccurate over much of the part's potential operating region, and/or have poor fidelity where you need it
  3. Programs and designers greatly overestimate the confidence gained from nominal performance and limited statistical data
  4. Programs completely underestimate the man-hours, schedule, and resources required to perform a WCCA


More to Come…

Worst (Best) Case Happens Every Day

Many don't believe that the tolerance stackup is reasonable. That parts or circuits can be as bad as the stackup says they are. The total tolerance stackup includes Initial, temperature, aging, manufacturing and in Space, radiation tolerances. In some cases, these are largely beginning of life and in some cases, more end-of-life. But the bottom line is worst case happens every day!

Small Satellite Trending & Reliability 2009-2018
This paper quantifies trends in small satellite utilization, reliability, and capability using a database of all small satellites. “Mission-ending failures are most likely to be attributed to the communication subsystem (26%) or power system (18%). Unattributed failures account for another 23%, with the other subsystems accounting for the remainder.”

Here's this month's light-hearted look at how out of tolerance conditions can cascade and why you need to perform WCCA.


Shocking moment two Carnival cruise ships crash into each other


Texas Man Killed by Exploding Vape Pen


Jeffrey Toobin Zooms

New Yorker writer and CNN analyst Jeffrey Toobin didn't just expose himself during a Zoom work meeting, “I believed I was not visible on Zoom. I thought no one on the Zoom call could see me. I thought I had muted the Zoom video.''




Why Perform a WCCA

Power Integrity Video Series: How to Design for Power Integrity

What Is PDN and Why It's Important


SPICE Models Need Correlation to Measurements


How To Design Power Supplies For Sensitive Circuits


Automotive WCCA Example Report - Simulating Stability and EMC/ESD Transients for Automotive Power Supplies


BOOKS: Switch-Mode Power Supply Simulation w/ PSpice and SPICE 3

NEW WCCA Blog Article:

WCCA Escapes


Escapes” is a euphemism for all the excuses programs, program managers, engineers, and reviewers use to curtail or eliminate WCCA associated activities. It is essential that all the elements noted in the (first) Going It Alone blog section, necessary to perform the WCCA, be brought together along with the right software, people, test data, and experience. With each hurdle, the analysis will stall, impacting the level of rigorousness, and the veracity of the conclusions.

Click to Read - “Too Many Escapes and Biases” Blog…

WCCA Blog Article - Resistor Aging

Coming Next!


Stay tuned for the Next blog in the March newsletter on Resistor Aging Tolerances where we discuss what's a reasonable aging/combined environments tolerance for resistors.


WCCA Engineers Needed
Why you save money outsourcing.


Engineers that can perform worst case circuit analysis (WCCA) are in short supply. And AEi Systems has them.


If you need WCCA, Stress, power integrity analysis, radiation analysis, or testing support for any program, please let us know.


Its understandable that customers generally want to perform WCCA in-house. Our experience is that that is not a good idea for two reasons. First, independence is lost. Second, we have several advantages that allow us to perform analysis more quickly and more inexpensively.


You may be right about being able to do your own analysis in a reasonable manner, however, you would be the exception.  In the majority of cases, WCCA reviews have revealed that it doesn't go well for those who do analysis of their own designs. I would be happy to review one or more of your worst-case analyses, at no charge, and let you know how it compares to what we would perform/the Aerospace TOR standard.


But here is something to think about. We are not trying to displace in-house efforts. Just to be an add-on.  We are happy to work in conjunction with in-house resources, as a parallel asset.


We are the leaders in the world at worst case analysis and the variety of skills necessary to perform such analyses. We have decades of experience is dealing with NASA and government organizations such as Aerospace Corporation when it comes to what they expect from an analysis. I am one of the authors of the Aerospace TOR-2012(8960)-4 on WCCA, as well as an SME on the subject.


All of the major IC companies use our models. We perform WCCA for all of the major primes. We are in your backyard.

Our experience, expertise, skills, IP and resources are already here and available.


Here are a few other reasons why we believe we can improve you team's total throughput and likely be a better and more cost effective solution.


What makes AEi Systems WCCA Unique and Special

We are Faster


We are More Accurate and Rigorous


We are Independent


Together these give AEi Systems a tremendous time and cost advantage compared with other resources.


They give you a better product and an analysis done more quickly and at a lower overall cost.


Finally, AEi Systems is the standard in the industry for this type of work. Our analysis carries weight. It is viewed with tremendous respect and that can be a distinct advantage for you as your customers evaluate your reliability.


We are happy to work in conjunction with in-house resources, as a parallel asset, but if you think we can benefit your company or program please do give us a call.

Notable Event: NASA's Perseverance Rover Landing on Mars - Thursday, Feb. 18, 2021, starting at 3:00pm EST


     Less expensive and more cost effective than in-house resources 

  • Our full-time team of top engineers with focused backgrounds in reliability, design, WCCA, and test has all the required core competencies to perform with great efficiency.
  • We have a significant number of SPICE models already made. We have Parts Variability Databases. We have Radiation Data. Even if you have in-house resources, dealing with models and tolerances can take a significant amount of time. AEi Systems puts the money and time savings in your pocket as we do not charge extra for this valuable IP
  • Analysis is all we do; Keep your in-house designers doing what they do best.

    Faster than in-house resources - ready to go 

  • Our proprietary software tools, library of proven SPICE models, and our 20 years of analytical engineering experience keep your team ahead of schedule
  • No bias - We introduce "checks and balances" to your design process/SDRLs

How can we help you?  Contact us for more specific information or a no-obligation quotation.

 AEi Systems Inc. -  USA
+1-702-625-0568 ▪