austriamicrosystems AS3560 and AS3561 stereo headphone amplifiers

austriamicrosystems has announced the AS3560 and AS3561 stereo headphone amplifiers for mobile phones, portable navigation devices, music/media players as well as other devices that use headphones.

The 30 mW amps continuously adjust the supply rails in response to the input signal, thus minimising power consumption when compared with class AB amplifiers.

The AS3560 is a class G amp, while the AS3561 extends the power savings even more with a class H. Class G 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 minimise the effects of ground noise and EMI susceptibility and also feature a low quiescent current of 1 mA with both channels enabled. The shutdown current is less than 5 µA.

Audio performance remains good with >100 dB SNR at 1 VRMS and THD of 0.02% at 16 Ω; . The integrated charge pump generates a symmetric negative supply for true ground output signal levels, which saves space and minimises system cost by eliminating the need for DC blocking capacitors.

An I2C bus allows volume control with 32 gain steps as well as independent channel control.