What's your power priority?

1/3/2010 3:33 PM EST

For battery-power designs, lower power means more operating time before the batteries must be recharged or replaced. Even a modest 5% or 10% decrease in consumption is usually worth the cost, depending on the application or market, of course. In contrast, for AC line-operated products, lower power operation really plays out in thermal dissipation issues more than power-source issues, since another few watts from the line is usually not as big a deal as reducing internal heating, and thus cooling requirements, in the box. In fact, a few milliwatts saved in a line-operated device is usually insignificant. And for big applications, such as running a multi-horsepower motor, a few milliwatts saved is usually meaningless, unless it means that a smaller MOSFET driver can be used, or a driver heatsink will be unnecessary.

Low power usually saves money, but not always. Before you rush to put that low-power IC on your BOM (bill of materials), ask yourself the eternal, basic engineering questions: Why am I doing this? Is the "pain" worth the gain? What are my priorities? What are the tradeoffs and downsides, if any, of going this route? Will I be unnecessarily limiting my list of approved vendors?

Then you can make an informed decision, without going the low-power route just to be trendy and have a nice PR statement. It wasn't that long ago when consumer multimedia amplifier in "stereo" systems boasted, right on their front panels, that they incorporated one-bit DACs, as if that would impress the customer. And where are those boasts now?♦