AEi Systems | WCCA Training

WCCA SAVVY
A tutorial on Worst Case Circuit Analysis and Reliability Performance

Benefits
This course provides the perfect opportunity to learn about worst case analysis, its methods and its processes. The course also emphasizes the product reliability improvements that are possible when WCCA is combined with MTBF, FMECA, and Stress and Derating analyses.

The course is designed to provide the participant with the fundamental skills and knowledge required to perform a Worst Case Circuit Analysis (WCCA or WCA). Participants learn the importance of this analysis and the different methods which can be utilized. The proper documentation format for communicating the analysis results is introduced with detailed and complete examples allowing the participant to gain a full understanding. In-depth tolerance studies and their evaluation are presented for most common electronic components.

“WCCA Savvy” is taught personally by Steve Sandler, renowned WCA expert and founder of Analytical Engineering.

This one or two day seminar is beneficial for both the novice wanting to learn worst case analysis concepts, as well as the engineering manager looking for an update on this vital technology.

Each class is specially tailored to the individuals, the company, and the disciplines (power, RF, IC) chosen by the students attending the particular seminar. Circuit examples, issues, and documentation techniques will be used that address the specific problems and pitfalls that the students are encountering in their daily jobs.

Upon completion, participants will be able to:
1. Learn the importance of why we perform a worst case analysis.
2. Learn the methods used in performing the analysis, and when to use each method.
3. Learn the proper documentation methods.
4. Learn to deal with poorly defined tolerances.

Course Background
The “WCCA Savvy” seminar has been taught at major corporations across the USA including Motorola, DELL, Canadian Space Agency, Raytheon, and General Dynamics. The AEi instructors are experienced at teaching worst case analysis to engineers with all levels of engineering background.

Topics To Be Covered

Introduction to Worst Case Circuit Analysis

WCCA Structure and Methods

Component Tolerances and Design Concerns

Analog, Digital, and RF WCCA Guidelines

Selected Examples

Accounting for Select At Test’s (SAT’s)

Stress and Derating Analysis

Common errors

How and why do we need to validate the design and analysis?

Documentation and Essential Formats

Detailed Course Outline
1. Introduction to worst case analysis

What is a Worst Case Circuit Analysis?

Why do we do it?

When do we do it?

To what extent do we do it?

Who should perform it/Review it?

Why is it so important to validate it?

Cost of doing or not doing a worst case analysis

Electrical test as an alternative: reasons, methods and limits

2. Worst Case Circuit Analysis Process

Methods of analysis
      Sensitivity
      EVA and RSS Computations
      Monte Carlo Analysis
      Digital: Timing Margin, Transmission Line, Noise, Decoupling,
            Fanout, Logic Compatibility, Physical Layout Analysis
      Analog: Specification Compliance, Regulation, Stability, Filtering, EMI, Magnetics
      RF Circuits

3. Analysis Task Compilation

What to Analyze

Determining Critical Parameters

WCCA Task Description Pitfalls

Handling Compliance Requirements

4. Part tolerances / Design Concerns

Tolerance Database Structures

Calculating Tolerances
      Radiation and Aging Tolerances
      Extrapolation (Arrhenius models)
      Resistors, Capacitors, Diodes, Zener Diodes
      Transistors, Mosfets, Transformers and inductors
      Digital IC’s, Analog IC’s
      Low Beta hFE analysis

Dealing with Poorly Defined Tolerances

5. Documentation

Why is documentation important?

What is included in the report?

Formating a report

Report examples

Reviewing a WCCA

Dealing with Non-Compliances

Dealing with Design Changes

Document and File Storage

6. Analysis Tools

Digital, Analog, RF

MathCAD and the Benefits of Mathematical Computations

SPICE Simulation Pitfalls

SPICE Modeling
      Reviewing Vendor libraries
      Modeling Pitfalls
      Diodes and Zener Modeling
      Subcircuit Model Examples

7. Selected Worst Case Circuit Analysis Examples

CLR79 capacitor model

LM193 Oscillator Analysis

Mixed Mode Example

LDO and Three Terminal Regulator Example

Mosfet Voltage Regulator

Optional Topics

Improving Reliability

MTBF: Parts Count vs. Stress-Based

FMEA, FMECA and Fault Simulation

Stress and Derating Analysis Guidelines

Radiation Analysis: Single Event Effect, TID, Neutron Fluence, SEU, SET, SEL, SEGR, SEB

Course Instructor: Steve Sandler, Founder and Principal Engineer
Mr. Sandler has over 20 years experience in the design and analysis of power conversion equipment for military and space applications. In his current position Mr. Sandler is responsible for the design, worst case analysis, reliability analysis, and FMECA analysis of satellite & power electronic systems. Past projects include: Milstar II Defense Satellite, International Space Station, Tempo, P-81, HS-702, ICO, LS-1300, Mabuhaysat, Globalstar, Omegasat, NSTAR and many others.

Mr. Sandler also personally designed and directed the development efforts behind AEi’s own line of space, military and commercial DC to DC converters, and developed a comprehensive power IC model library for SPICE simulators.

Mr. Sandler is author of several books and numerous articles on power supply modeling and simulation including, “SMPS Simulation with SPICE 3”, and “The SPICE Handbook of 50 Basic Circuits”. From 1985 – 1995 Mr. Sandler worked for ST Keltec Corp. Space Power Group as an application engineer and sales and product manager. Before 1985, Mr. Sandler held positions with Telephonics Corp. Signal Technology, Aerospace Avionics Inc., and Lambda Electronics.