A compact stereo headphone driver chip with an I2C bus control interface hails from STMicroelectronics. It's intended for portable applications such as mobile phones equipped with FM radio that need quality audio output and minimum additional components. The TS4975 amplifier can deliver up to 40 mW/channel continuous average power into 16-ohm loads on a 3.3-V power supply. The I2 C interface enables a 14-step volume control range from 18 to -34 dB.
The 1.8- by 2.3-mm flip-chip device allows a phantom ground output configuration to eliminate the bulky capacitors required for single-ended designs. It features ultra-low standby current of 0.6-ΜA and can operate on power supplies between 2.5 to 5.5 V. Pop and click noise-reduction circuitry eliminates turn-on and turn-off noise. Nine operating modes, which include various combinations of input and output switching, plus independent channel shutdown, are also controlled through the I2 C interface. Further information can be found at www.st.com.