The LM4545 is an audio codec for PC systems which performs the analog-intensive function of the Analog Codec '97 Rev 1.03 Architecture. Using 18-Bit A/D and D/A converters, the LM4545 provides 90dB of dynamic range. The LM4545 was designed specifically to provide a high quality audio path and provide all analog functionality in a PC audio system. It features full duplex stereo A/D's and D/A's and an analog mixer with 4 stereo and 3 mono inputs, each of which has separate gain, attenuation and mute control. In addition, the LM4545 provides a stereo headphone amplifier with an independent gain control and National's 3D Sound stereo enhancement technology. The LM4545 features AC-Link, a synchronous, fixed rate serial bus for connection to the digital AC '97 Controller. The separation of the analog and digital functions of the AC '97 architecture allows for system design flexibility and increased overall performance.