austriamicrosystems has released two stereo headphone amplifiers for mobile phones, portable navigation devices, music / media players and any media device that uses headphones.
The new 30 mW headphone amplifiers continuously adjust the supply rails in response to the input signal and minimize power consumption compared to traditional Class AB amplifiers.
The AS3560 is a Class G amplifier while the AS3561 extends the power savings even more with a Class H topology. Class G topology switches between three power rails, while the Class H adapts the power rail to whatever power is needed to drive the headphone volume. Both devices use differential line inputs to minimize the effects of ground noise and EMI susceptibility, and also feature low quiescent current of 1 mA with both channels enabled. The shutdown current is extremely low at less than 5 µA.
austriamicrosystems claims the audio performance remains excellent with >100 dB SNR @ 1 Vrms and THD of 0.02 percent at 16 ?, making the AS3560/AS3561 the best such devices available for power consumption and audio performance. The integrated charge pump generates a symmetric negative supply for true ground output signal levels, which saves space and minimizes system cost by eliminating the need for bulky and expensive DC blocking capacitors. An I2C bus allows volume control with 32 gain steps as well as independent channel control.
“Class G gives you all the benefits of a linear headphone driver in terms of sound quality, while minimizing the power loss“, commented Oliver Jones, austriamicrosystems’ Marketing Manager for Audio products. “This topology is without doubt the most efficient way to drive a headphone for cost vs. performance. But Class H goes even further, squeezing every last minute out of the battery.“
Availability and pricing
The AS3560 and AS3561 are available in a 16-ball 1.6x1.6 mm WL-CSP package and are priced at 0.95 US Dollars for the AS3560 and 0.98 US Dollars for the AS3561 for 1000 piece quantities. Both operate over a temperature range of -30 to +85 degrees C.