Introduction

The STA538 is a digital stereo class-D audio amplifier. It includes an audio DSP, a ST proprietary high-efficiency class-D driver and CMOS power output stage. It is intended for high-efficiency digital-to-power-audio conversion for portable applications. The STA538 also provides output capabilities for FFXTM. In conjunction with a power device, the STA538 provides high-quality digital amplification.

Features

■ Up to 96 dB dynamic range

■ Sample rates from 8 kHz to 192 kHz

■ FFXTM class-D driver

■ 1.5 V to 1.95 V digital power supply

■ 1.5 V to 3.6 V analog power supply

■ 18-bit audio processing and class-D FFXTM modulator

■ Digital volume control:

– +36 dB to 105 dB in 0.5 dB steps

– Software volume update

■ Individual channel and master gain/attenuation

■ Automatic invalid input detect mute

■ 2-channel I2S input/output data interface

■ Digitally controlled POP-free operation

■ Input and output channel mapping

■ 250 mΩ output CMOS Rdson

■ > 90 efficiency

■ 2 x 1.3 W (10 THD) on 4 Ω at 3.6 V

■ 2 x 0.7 W (10 THD) on 8 Ω at 3.3 V

■ Stereo headphone plus mono speaker application:

– 50 mW stereo into 32 Ω headphone, 1.2 W mono into 4 Ω speaker at 3.3 V

– 100 mW stereo into 16 Ω headphone, 1.2 W mono into 4 Ω speaker at 3.3 V