The AS3518 is a low power stereo audio codec and is designed for Portable Digital Audio Applications. It allows playback and recording in CD quality. It has a variety of audio inputs and outputs to directly connect electret microphones, 16/32 headsets and auxiliary signal sources via a 10channel mixer. It consumes less than 20mW in playback mode. Further the device offers advanced power management functions. All necessary ICs and peripherals in a Digital Audio Player are supplied by the AS3518. The different regulated supply voltages are programmable via the serial control interface. AS3518 also contains a Li-Io battery charger. The single supply voltage may vary from 1.0V to 5.5V. The AS3518 has an on-chip, phase locked loop (PLL) which generates the needed internal CODEC master clock. I2S Frame and shift-clock has to be applied from the processor for playback and recording. Further the AS3518 has an independent 32kHz real time clock (RTC) on chip which allows a complete power down of the system CPU.