Well, that was interesting

I spent today at the Texas (formerly Unitrode) power supply design seminar. The UK one this year was held in the motorcycle museum near Birmingham. It was at least a floor below the slightest phone signal, or glimmer of daylight.

From my point of view it was the best such seminar I have attended in at least the last ten years, because they covered two topics that I want to use in my work soon, and others that gave me useful extra understanding and analysis and modelling techniques that are likely to be useful frequently.

I'll try to avoid making everybody's eyes glaze over, but the part of my work I most enjoy is where the laws of physics meet the product. In my line of work, that normally means designing switched mode power supplies. Energy efficiency has always interested me, and a major design aim for switched mode is efficiency.

One useful feature of some types of smps is that they can provide more than one output, by making a transformer with extra windings on it. For example, the power supplies used in most desktop computers provide +5V, +12V, and -12V. Hear the wisdom of ancient Plautus! It is well known that if you draw lots of power from the main output of a power supply and none from the other outputs, those outputs normally provide much more voltage than expected. A 12V output could reach over 20V. It is easy enough to measure to what extent that happens, and then determine if remedial action is needed, once the power supply is designed and assembled. However, it is helpful to be able to calculate what will happen in advance, and, perhaps, calculate that simply adding a small LED to indicate that the 12V supply is present will draw enough power to prevent the voltage reaching an excessive level.

The first session covered a way to model transformers having multiple windings, and calculate this aspect of what a power supply will do before one is built and tested.

All the other sessions were at least interesting and thought provoking, but the case study of a solar powered lighting application demonstrated just how much better power supply design can be if, instead of analogue circuitry such as has been used for decades, you use a digital controller and make it all work using software. I expect to start designing something with a Piccolo DSP very soon. Some aspects of it may initially be difficult and confusing, but once I have learned what is needed I will be able to design some items a useful amount better. Cheaper and more energy efficient - which my customers always need. I await an evaluation kit.