Headset CODEC

Micronas has released its UAC 355xB high-performance system-on-chip family for VoIP telephony, USB phone and PC headset applications.

The device is a fully integrated headset CODEC (stereo audio ADC and DAC) with a DSP and USB 2.0 full-speed interface controller. The DSP handles all common sample rates and supports audio processing such as volume, bass and treble. The programmable five-band parametric equaliser enables adjustments of the frequency response.

Dynamic bass management is also provided. Integrated amplifiers allow direct headset connection including a subwoofer output with internal split filter. The microphone signal can be mixed to the USB audio data for sidetone or karaoke applications.

The chip supports 16 bit mono/stereo and 24 bit stereo for playback (D/A converter), and 8 bit mono and 16 bit mono/stereo for record (A/D converter). Performance figures include THD better than -85 dB and SNR of 96 dB (typ) for the D/A converter and THD better than -85 dB and SNR of 92 dB (typ) for the A/D converter. Generic ISO-playback endpoint is also provided for various applications (Dolby digital, MP3) via the I2C I/O interface.

The USB 2.0 full-speed interface controller uses the general-purpose input and outputs to connect volume and mute buttons, LEDs, etc. USB HID device class for audio controls is supported.

Via I2C master and appropriate PC application software, more complex peripherals can be controlled. The UAC 355xB itself can be remote-controlled via I2C slave operation. This allows communication pipelining between a peripheral I2C system controller and the USB host.

The use of an external EEPROM allows programmable VID/PID, strings, and even more complex customisation. These are small downloadable code sections, which can be added to the internal ROM.