Switching regulators suit low-noise operations

Advanced Analogic Technologies Inc. has unveiled the first device in an extensive family of switching regulators designed for low-noise operation. Based on a patent-pending architecture, the AAT2120 and AAT2158 synchronous step-down converters deliver significantly lower spectral noise and output ripple than competing switching regulators. These low-noise switching regulators represent the first of several generations of new switching regulator topologies now under development at AATI targeting high performance and high efficiency applications.

"Designers of noise-sensitive systems, such as mobile phones, media players or Bluetooth accessories, prefer to use higher efficiency switching regulators to maximise battery life, but often cannot because traditional switching regulators inject too much noise into the system," said Bill Weiss, product line director for AnalogicTech. "Instead they turn to low-noise, but lower efficiency linear regulators. Using a unique architecture which dramatically reduces spectral noise and output ripple, the AAT2120 and AAT2158 offer designers their first chance to take advantage of the power efficiency advantages of switching regulators in noise-sensitive communication, high speed interface and other applications."

Lower noise, output ripple
At lower currents, the AAT2120 and AAT2158 switching regulators produce half the ringing amplitude of competing switching regulators. This characteristic translates directly into lower noise being injected into the system. In system tests, the spurious energy, which is injected by the switching regulators, was reduced by 3dB. At higher currents, the two new converters produce approximately 25 percent less output ripple. By reducing injected noise and output ripple, the two new devices can improve the dynamic range performance of RF systems when compared to RF systems powered by traditional switching regulators.

At the same time the AAT2120 and AAT2158 offer all the traditional power efficiency advantages of traditional switching regulators. Power efficiency for the AAT2120 and AAT2158 reach up to 96 percent and 95 percent, respectively. Moreover, by operating at high switching frequencies, both devices minimise the size of external components.

The AAT2120 supplies up to 500mA output current, while the AAT2158 delivers up to 1.5A output for applications requiring higher levels of power. Both devices operate from an input range of 2.7-5.5V and support output voltages as low as 0.6V.

For protection purposes, both step-down converters offer internal soft-start, over-temperature and current limit protection. The new converters also extend system run time by adding 100 percent duty cycle low-dropout operation.

Qualified across the -40?C to 85?C temperature range, the AAT2120 is available in a Pb-free, 8-pin 2mm x 2mm STDFN package. It sells for 85 cents in 1,000 quantities. The AAT2158 is also qualified across the -40?C to 85?C temperature range and comes in a Pb-free, 16-pin 3mm x 3mm QFN package. It sells for Rs.62.69 ($1.55) in 1,000 quantities.

AnalogicTech will announce two additional members of its low-noise switching regulator product family, the 400mA AAT2146 and the dual 600mA AAT2713, in Q1 2008.