The LTC1174, a step-down converter that is designed specifically to eliminate noise at audio frequencies while maintaining high efficiency at low output currents, is described.
Portable communications products are densely packed with signal processing, microprocessor, radio frequency, and audio circuits. Digital clock noise must be eliminated not only from the audio sections, but also from the antenna which, by the very nature of the product, is located only inches from active circuitry. If a switching regulator is used in the power supply, it becomes another source of noise. The LTC1174 ...