The NAU88C22 is a low power, high quality CODEC for portable and general purpose audio applications.  In addition to precision 24-bit stereo ADCs and DACs, this device integrates a broad range of additional functions to simplify implementation of complete audio system solutions. The NAU88C22 includes drivers for speaker, headphone, and differential or stereo line outputs, and integrates preamps for stereo differential microphones, significantly reducing external component requirements. Also, a fractional PLL is available to accurately generate audio sample rate from 8kHz to 192kHz using any commonly available system clock from 8MHz through 33MHz.

Advanced on-chip digital signal processing includes a 5-band equalizer, a 3-D audio enhancer, a mixed-signal automatic level control for the microphone or line input through the ADC, and a digital limiter/dynamic-range-compressor (DRC) function for the playback path. Additional digital filtering options are available in the ADC path, to simplify implementation of specific application requirements such as “wind noise reduction” and speech band enhancement.  The digital audio input/output interface can operate as either a master or a slave.

The NAU88C22 operates with analog supply voltages from 2.5V to 3.6V, while the digital core can operate at 1.7V to conserve power. The loudspeaker BTL output pair and two auxiliary line outputs can operate using a 5V supply to increase output power capability, enabling the NAU88C22 to drive 1 Watt into an external speaker.  Internal register controls enable flexible power saving modes by powering down sub-sections of the chip under software control.