1. Design Requirement/Constraints
Ref: Voland, G., Engineering by Design. Addison Wesley, 1999
& Larry Hand, Peavey Electronics, 2000

2. So you have figured out what you are going to do (Problem Statement), what next?
Create the technical formulation of the problem!

3. A technical formulation takes an idea and translates it to an engineering context, complete with relevant objective technical and practical design constraints and appropriate theory and design methodologies needed to address the design.  It translates a design idea into a set of related, feasible engineering specific problems.

4. Constraints are a “Good Thing”
Define the boundaries within which the search for solutions must be conducted
Enhance the effectiveness of the design
Avoid designs that are illegal or hazardous
Make designs economically viable

5. Types of Constraints or Specifications
Can be broken down several ways
Example: Bus specification
Physical (dimensions, connectors, pins)
Functional (arbitration protocol, read cycle)
Electrical (impedance, max/min signal levels)
We will use
Technical Design Constraints
Practical Design Constraints

6. Technical Constraints Requirements on which technical aspects of the design hinges
Signal tolerances (> 30% duty cycle clock at 1MHz +/-1%)
Supply current range (.5 mA min to 100 mA max)
Power efficiency (83% supply efficiency at rated load)
Speed (interrupt service latency < 1 S)
Conversion rate (12-bit conversion at 500Ksamples/sec)
Transmission distance (100 M with unobstructed view)
Quantization error (+,- 5mV)
Frequency response (20 Hz to 20 KHz, +/- 3 dB)
Signal-to-noise ratio (50 dB min)

7. Practical Design Constraints Broader issues affecting design’s success
Economic
Environmental
Sustainability
Manufacturability
Ethical
Health and Safety
Social and Political

8. Economic Limits on Production Cost Depreciation of Equipment
Operating Cost
Service or Maintenance Requirements
Existence of Competitive Solutions in the Marketplace

9. How is Cost Determined (Note that cost is NOT price)
Material Cost
Labor Cost
Manufacturing Burden
Selling, General, and Administrative Expense (SG&A)

10. Example Case: How Much does it Cost
Material Cost % of Total Cost
Unit Price * Quantity for all (Bill of Materials) BOM items
Labor Cost --- 8% of Total Cost
Direct labor or value added labor required to manufacture the product

11. How Much Does it Cost Manufacturing Burden --- 17% of Cost
Indirect Labor
Utilities
Facilities
Employee Benefits
Depreciation, rent, etc..

12. How Much Does it Cost Sales/General and Administrative -- 23%
Cost of Selling the Product
Sales commission
Advertising
Service and Warranty
Corporate Management
Research and Development
Bad Debt, etc..

13. Environmental Temperature Ranges Moisture Limits Dust Level
Intensity of Light
Noise Limits
Potential Effects Upon People or Other Systems

14. Sustainability If you birth it, It’s always your baby
Customer complaints
Obsolete & sole-source Parts
Warranty claims and field failures
Specification changes in standard components

15. Manufacturability Programs for Automated Assembly Equipment
Axial Sequencer and Insertion
Radial Insertion
DIP Socket and IC insertion
Surface Mount Chips, IC’s, Odd Shaped Components
Automated Test

16. More things to consider
Mechanical Design and Packaging
Space Allocation or Dimensional Requirements
Weight
Material Characteristics
Power Requirements
Protect Unit During Shipment
Attractive at Point of Sale
Advertising
OEM or Consumer packaging

17. Legal Governmental Safety Requirements
Environmental or Pollution Control Codes
Production Standards

18. Health and Safety Human Factors/Ergonomics
Users Characteristics
Strength
Intelligence
Anatomical Dimensions
Visual Acuity
Hearing Discrimination
Reaction Time
Reading Skills

19. Social and Political Agency ApprovalsUL
CSA
FCC
NOM CE
NEMKO
DEMKO
VDE
IRAM
SASO
SANZ
SAA
JIS
and more.....

20. Sources of Engineering Standards
Companies
Engineering Societies
Governments (U. S., others)
Special Interest Groups
Federations of Private and Public Interests (American and International)
Independent Laboratories

21. Examples See http://www. dma. org/~rohrers/subject/standorg
Examples See for extensive list of links
ACM (Association of Computing Machinery)
AES (Audio Engineering Society)
ANSI (American National Standards Institute)
EIA (Electronic Industries Association)
ESD (Electrostatic Discharge Association)
IEEE (Institute of Electrical and Electronics Engineers)
ISO (International Standards Organization)
ITU (International Telecommunications Union)
OSHA (Occupational Safety & Health Administration)
PCI SIG (PCI Bus Special Interest Group)
UL (Underwriters Laboratories)
USB Developers (Universal Serial Bus Developers Forum)