Planning and Communication—Key to Optimizing Your Design Time

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How many times in your career have you been asked, “Can we pull in the schedule?” Whenever you hear that question, can’t you feel the hair on the back of your neck standing up?

This type of question can be hard for us to hear simply because it is the wrong type of question. The core issue, most often, is how to best use our time during the design phase of a project. Optimizing design time consists of managing internal and external elements within our control and influence. Internal factors we have control over are our skills, time, and behavior. External factors we have influence over are requirements, design reviews, and stakeholder interactions.

Personal skill management is the foundation of being an effective designer. The more ideas and methodologies that you encounter/use, the more depth and breadth of knowledge you will have to make well-informed decisions. Here are two general rules of thumb to help guide personal skill development regarding design efficacy.

1. Generalists should be well versed enough to convey requirements, design decisions, and interdisciplinary tradeoffs to specialists.

Early in my career I was working on a project designing a mixed digital/analog IO board and needed to communicate to the power supply engineer what my power requirements were for my board. The good news was I had a previous design to base my design on and could take measurements from that board to give a reference. The bad news was I did not know what was important to communicate to the power supply designer. I took average voltage/current measurements, added some fudge factor and handed them over to him. He asked me how I got the numbers, and I replied that they came from the previous design—with additions based on increased circuitry on the new design. The measurements I made were static and did not account for any dynamic power draw.

It turns out the -15V had an average current draw of tens of milli-amps and a peak of nearly 500 mA. The power supply engineer designed a cross-regulated power supply with two outputs: +15V and -15V. The power supply regulation was based on the +15V since its current draw was about two orders of magnitude that of the -15V. When the -15V was hit with sourcing 500 mA, it would sag significantly. The power supply monitor would then indicate a fault and the associated circuitry on the processor IO board would not work as required. The result was a re-design of the power supply due to my lack of understanding of what the specialist (power supply designer) needed from me.  

To read this entire article, which appeared in the May 2021 issue of Design007 Magazine, click here.    


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