You know what? I can’t answer the question…

I didn’t get a very good degree when I left university, for various personal reasons, but it’s never really affected my career, as I’ve learnt a lot more about electronics since leaving university.  I have a great deal of respect for people who spend more time in academia but sometimes even the most educated of people can be really daft.

Back in the day, Harris Semiconductor (now Intersil) made a non-isolated offline switcher, capable of a low voltage output at a few milliamps of current.  As long as the customer didn’t need isolation, it made a great solution for a bias supply for circuitry, for example.

I went to see one customer who had expressed an interest in this part and we discussed the merits of it in their application.  The company was a university spin-out and I met with the Technical Director (a Professor) and a young graduate project engineer.  It sounded a good fit until the Professor asked about EMI (Electro-Magnetic Interference).

I was well prepared: I had an example layout that met the German VDE standards for conducted emissions (this was before the harmonised EU standards and the VDE spec, which eventually became the EU standard, was the most demanding).  Ta da!

“No, I mean what is the EMI performance of the chip?” asked the Professor.

“Well, it depends on the layout; and in order to help you meet the conducted emissions standard, we’ve produced a sample layout that does…”

“Never mind the layout, what about the chip itself?” persisted the Professor.

Now, anyone who knows about electromagnetic interference knows that a switching converter generates interference but how bad that affects the environment depends on the layout.  With a neat layout and adequate filtering, you can meet the limits set out in whatever standard you are trying to meet.  If you have a poor layout, for example with long tracks acting as antennae, then you’re going to fail the limits.  I could see that the young graduate engineer “got” this but was too deferential to his boss to say that he was wrong.

How did I resolve this impasse?  Did I tell him he was a fool?  Did I embarrass him in front of his junior colleague?

To paraphrase Monty Python, ‘Brave Sir Martin ran away!’  I made my excuses and left.  “You know what,” I said, “I don’t think this part is suitable for you after all.  I’ll not take up any more of your time.”

It goes to show that there are some questions you just can’t answer, especially if an educated person fails to grasp a fundamental point.

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