April 2017 – Best Practices in Hardware Development Part I

For over 30 years, The Omnicon Group has been committed to advancing hardware development best practices plans and procedures for our customers. Omnicon engineers are experienced designers who develop highly reliable electronic hardware. Our engineers create efficient plans and procedures to streamline testing while ensuring accuracy and complete verification to requirements in the least amount of time. Omnicon engineers apply best practices in hardware development to all efforts in order to achieve the highest level of customer satisfaction. 

What are some Best Practices in Hardware Development? 
First and foremost, have a documented process and follow it. This applies to hardware development at the board, box, or chip level, and is akin to the process used in software development. Having a process and following it ensures that you think things through, review what has been done, and develop the correct “end item” that satisfies the needs of the customer. 

Do I really need a Process? 
Absolutely, even if you didn’t utilize or follow a documented process in the past. A documented process provides the checks and balances necessary to minimize risk and ensure that what we develop operates as intended. The process includes five phases: 
  1. Specify: identify the need the “end item” or hardware, in this case, must satisfy
  2. Conceive: conceive or conceptualize how to satisfy that need
  3. Design: analyze, describe, and define with sufficient detail to progress towards a physical realization of the item
  4. Realize: manufacture, prototype, or otherwise produce an implementation of the design and demonstrate that the “as designed”, “as built” item is feasible, and operates as intended
  5. Verify and Validate: produce and compile evidence indicating the end item satisfies the need for which it was designed

Next month’s blog post will discuss in further detail the five phases of the hardware development process. 

Do I need to Prototype? 
Definitely. While simulation is important and can provide insight into the inner working of a design, the simulation and output produced is only as good as the model or input data provided and may be incomplete. In areas where a new technology is being utilized, data for simulation may simply not be available. Where a known technology is being implemented for the first time, or where a device is being used in a unique or unusual way, prototyping is invaluable. There is no substitute for actual hardware. 

Use of solderless breadboards, wire-wrap, or point-to-point wiring techniques were the norm for prototyping in the past using through-hole devices. Today, however, with Surface Mounted Devices (SMD), the prototype typically takes the form of a quick turn PCB. While component vendors may have “evaluation boards” that can provide putting actual hardware in the hands of the engineer in the shortest amount of time, oftentimes these are not the best. They may not be representative of the specific design variant or a practical solution that is space or otherwise constrained. But DO take note of recommended placement and routing guidelines as an otherwise “good” design can behave badly when poorly implemented in a PCB layout. 

What about the schematic? 
The schematic diagram is a visual representation of the components and interconnections between those components forming a circuit. The purpose of developing a schematic is two-fold. First, and of utmost importance is that the schematic accurately represents the design such that subsequent activities (i.e. PCB layout and Parts procurement) can commence. The second aspect of creating a schematic is to convey, express, and communicate the circuit to someone else. It is necessary but far from sufficient for a schematic to be correct. If a schematic is likely to mislead, it is a bad schematic even though it may be correct. Since the visual representation of a schematic is intended to communicate information, a good schematic does this quickly, clearly, and with a low chance of misunderstanding. 

What about components? 
Do not use components beyond their specified ratings. While this may seem obvious, all too often this key concept is overlooked, ignored, or simply forgotten. Some common mistakes include: 

  • Using a device outside its recommended operating temperature range (while a device may work outside the specified operating range with some degradation in performance, there is no guarantee that all similar devices will do so)
  • Failing to ensure input/output compatibility in mixed signal designs (e.g. 3.3V device having 5V tolerant inputs)
  • Exceeding the Sink/Source or Fan-out capability of a device (do not demand more than a device is capable of providing)
  • Exceeding the common mode input range of an Op Amp (especially in non-inverting amplifier configurations as signals approach these limits)
  • Failing to analyze the actual performance of IC’s claiming “Rail-to-Rail” performance (capability may be limited based on gains, impedances, loads, and temperatures)
  • Failing to provide for fault protection (short circuit withstand capability)
  • Failing to analyze transient conditions that may result in electrical overstress
  • Failing to consider voltage and/or dielectric ratings of transformers and inductors

Omnicon engineers have accumulated these best practices in hardware development from over 30 years of experience. Omnicon’s processes are based on stringent guidelines of widely accepted hardware development documents which address the entire life cycle processes for hardware intended for the most critical or vital applications. At Omnicon, we put our customers first, and our goal is to deliver the best possible product.

Tags: analysis, best practices, development, hardware, hardware development, ratings



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