The WM8994 is a highly integrated, ultra low power hi-fi codec with an integrated stereo Class D and AB speaker driver, and a Class W headphone driver to minimize power consumption during audio playback. The device requires only Vbatt and a 1.8V supply, generating all other internal supply rails from integrated LDOs. Stereo full duplex asynchronous sample rate conversion and multi-channel digital mixing combined with powerful analog mixing to support a wide range of different architectures and use cases. A fully programmable parametric EQ provides speaker compensation and a dynamic range controller can be used in the ADC or DAC paths for maintaining a constant signal level, maximizing loudness and protecting speakers against overloading and clipping. A smart digital microphone interface provides power regulation, a low jitter clock output and decimation filters for up to four digital microphones. A MIC activity detect with interrupt is available. Active ground loop noise rejection and DC offset correction help prevent pop noise and suppress ground noise on the headphone outputs.