The LM4540 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 LM4540 provides 90dB of dynamic range. The LM4540 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 2 stereo and 3 mono inputs, each of which has separate gain, attenuation and mute control. In addition, the LM4540 provides National's 3D Sound stereo enhancement technology.