At Upverter, we love talking to hardware engineers and learning about how their teams review schematics. It seems that everyone has put together their own unique method:
from buying large-format printers and printing everything out on 11″x17″ paper, to long email threads in Outlook; running WebEx conferences to making PDF bookmarks.
Despite the variations in workflow, most of them agree that 2 of the most important factors in finding errors are:
- How thorough you are
- How experienced you are
We know everyone is crunched for time and usually isn’t as meticulous as they’d like to be. We also know that gaining experience often comes from mistakes: making them yourself or learning from the ones your colleagues have made.
If you’re new to reviewing schematic (or have simply been neglecting it), here are some general guidelines to help you become an effective reviewer.
- Read the datasheet of each component! It sounds so obvious, right? You’d be surprised at how many reviewers skip this. This is one of the most valuable things you can do. Read the datasheet, understand how the part functions, how each pin should be connected, and then check the schematic. With practice you’ll become an expert at reading datasheets quickly and figuring out which parts are important for schematic review. It’s not as daunting (or time-consuming) as you might think.
- Collect all the supplemental documentation on the vendor’s site. Look for reference designs, evaluation boards, application notes, layout guidelines, etc. Then quickly compare your schematic against each of these documents. Any differences might signal a mistake. This is a fast way to check connectivity with confidence.
- Leverage the vendor’s field application engineers. FAEs are often very knowledgeable on how their vendor’s components can be used in a design. Send them your schematic and they’ll be happy to review it for you. They often have their own internal checklist for this purpose.
- Create a culture of asking questions. Why is this connected this way? Why did you choose this part? How do you plan on dealing with X? When someone verbally walks through something, it often triggers important things that they hadn’t considered before. You’ve probably experienced this phenomenon yourself. There’s a ton of value in not only knowing the answer, but in this associative way of thinking.
- Share “lessons learned” with each other. Create a communal list of errors you’ve found on previous boards. Review this list before looking at a schematic (or designing one from scratch!) to remind yourself of things to watch out for. Have your senior engineers get this list started.
- Review the schematic in small chunks as it’s being designed. Many engineers don’t have the time to be thorough when faced with a giant schematic. It can be a daunting and a stressful process. Instead, consider sending out a small piece of the schematic every few days during the design process. This way reviewers are only faced with one circuit or component. It’s not only more manageable, but also an enjoyable way for engineers to familiarize themselves with the overall design as it comes together. They’ll be much more prepared for the big review at the end.
While some of these guidelines might seem obvious and basic, it’s important to build on a good foundation of reviewing schematics. There are simply no shortcuts. Once you incorporate these steps into your work and process, it will be loads easier (and faster) to prevent errors from actually becoming a problem.
Stay tuned for a checklist of specific circuit errors to watch out for.