We recently filmed a short video with Tony Armstrong from Analog Devices who took us through a demonstration of a new kind of circuitry that cuts down the noise from switching power supplies. Switchers are notoriously noisy but can usually be fixed with filtering. Armstrong illustrates that with a non-synchronous regulator running at about 300 kHz. It generates about 50 to 60 dB of noise. He compares this to a new device from Linear Technology called a Silent Switcher. It basically takes the switching regulator, divides it in two halves, ties the outputs together, in so doing creating opposite inputs that give magnetic cancellation.
Placing the loops close together significantly reduces the emissions, by tens of dB, Armstrong says. In Silent Switcher 2 technology, which is indicated with an S suffix, filter capacitors have been included inside the package on the laminate. This brings significantly enhanced noise performance, even better than the first generation. And it’s almost immune to layout problems, Armstrong says.