What is good electronics design?
Electronics is now omnipresent in everything including cars, toys, toothbrushes, watches, televisions, pacemakers and everything in between. In 2017 the number of ARM processors made passed the 100 billion mark. There are new products which include electronics released every day
But what differentiates good electronics from average, poor or even dangerous designs?
- Which products are going to fail after a short period of use?
- Which ones fail to meet the required legal compliance?
- Some could have issues serious enough to force a product recall?
- Which ones take so long to get to market that competitors have already stolen a march or that the development budget has been spent on achieving perfection (in the engineers mind) on features that the majority of customers won’t use or don’t care about?
Understanding good electronics design
Good electronics design is much more than a thorough theoretical knowledge of the varies aspects of the discipline. That’s including analogue design, digital logic, radio frequency communication, control systems theory, power supply design and printed circuit board layout. Good electronics design has to include understanding the application. It has to include what is important: seeing the product and its use through the users eyes.
An experienced and technically capable team can question and seek clarification of the product requirements. The start of the project then has a well-defined, well considered and technically achievable requirements specification. By contrast, inexperienced electronics design teams often jump straight into the design. they don’t know what needs to be delivered. They will, almost certainly, have to change their approach and throw away pieces of work as clarity grows.
A pragmatic approach needs to be adopted, balancing the commercial needs of time and cost with quality and reliability. This balance is different in each industry, with light up toy swords at one end and aerospace control systems at the other. Nevertheless a conscious decision must be made and then embodied in the electronics design, test, verification and approvals process.
Good electronics design should also embrace a working knowledge of component suppliers, product lifecycles and lead times. There is little point in designing a product where the components are unavailable at product launch, or which have become obsolete during approvals.
Refer to the electronics design requirements
During the electronics design process the requirements should be regularly referred to. It is not enough to just fulfill the requirements. Good electronics design also requires that engineers are aware of the products limitations and potential failure modes. These can then be flagged up and have decisions actively made about whether these are important and need dealing with.
The manufacturing process means that electronic components are not all identical. They are manufactured to perform within a range of characteristics. they have tolerances and vary with various operating environments including applied voltage and temperature. This doesn’t matter too much when products are being made in small numbers. In a continuous batch, typical of a 5-10 unit prototype run for development as it is likely that the components are similar having been made at the same time. Where this can cause problems is when the product becomes successful and starts to sell in much higher numbers. At this point the build-up of tolerances or the use of products at the ends of its temperature specification can begin to show up. They will show up as seemingly random faults or failures. Good electronics designers take the spread of operating parameters and tolerances into account during the design. They then test the products over the expected working range of those parameters and a little beyond.
Prototyping and testing is vital to get to a first working printed circuit board. Wherever possible, when trying out new design ideas, they shouldn’t be first tried out on a printed circuit board but instead be simulated and breadboarded. This can save a lot of time and money for an unnecessary pcb re-spin, taking an hour or two to try out the idea up front can ensure that errors can be quickly corrected.
Design reviews from peers also help to reduce errors and omissions before manufacturing a pcb. When an engineer has been working on the same job for a while it is easy to become blind to any issues. Having a design review helps avoid this. The reviewer is a fresh pair of eyes and the engineer, whose design is being reviewed, tends to look at things a little differently as they explain their approach and thinking. Design reviews can be difficult things when ego’s and emotions are involved. However, its vital to be prepared to be wrong. Its much better for a mistake to be found before a board is made than to find it afterwards during bring up and debug.
When prototype pcbs are received good electronics engineers ensure they are tested as thoroughly as possible. The aim is to ensure every aspect of the board has been tested and where necessary corrected if issues are found.
Finally, the least popular activity for the majority of engineers is documentation but this is an essential part of good electronics design. Documentation serves a number of purposes including building up evidence of compliance for a technical construction file, explaining the circuit operation to an engineer who picks up the job in the future as a handover pack and to keep the test setup information and evidence to allow it to be repeated in the future if issues occur.