MAX9867 Ultra-Low-Power Stereo Audio Codec

The device has stereo differential microphone inputs that can be connected to analog or digital microphones. The single-ended line input signal passes through a configurable preamplifier and can be input to the ADC for recording or directly switched to the headphone amplifier for playback. The auxiliary ADC channel can be used to track any DC voltage.

The stereo headphone amplifier supports differential, single-ended, and capacitor-less output configurations. In the capacitor-less output configuration, the device can deliver 10mW output power into a 32Ω load. A comprehensive click-and-pop suppression circuit eliminates audible noise during volume changes, startup, or shutdown.

Using Maxim's proprietary digital circuitry, the device accepts any system clock in the 10MHz to 60MHz range. This architecture eliminates the need for an external PLL and multiple crystal oscillators. The stereo ADC and DAC channels feature user-configurable voice-band or audio-band digital filters. The voice-band filters provide additional attenuation in the GSM packet band, with greater than 70dB of stopband attenuation at fS/2.

The MAX9867 operates from a single 1.8V supply and supports logic levels from 1.65V to 3.6V. Volume, signal mixing, and normal operation are controlled through a 2-wire, I²C serial interface.

The MAX9867 is available in a small 2.2mm x 2.7mm WLP package with 0.4mm ball pitch. It is also available in a 32-pin 5mm x 5mm TQFN package.

Key Features

1.8V single power supply

6.7mW playback power consumption

90dB Stereo DAC, 8kHz ≤ fS ≤ 48kHz

85dB Stereo ADC, 8kHz ≤ fS ≤ 48kHz

Auxiliary ADC for battery measurement

Supports any master clock frequency from 10MHz to 60MHz

Support stereo digital microphone input

Stereo analog differential microphone input

Stereo headphone amplifier: differential, single-ended or filter-capacitor-free configurations

Stereo Line In

Voice band filter, stop band attenuation greater than 70dB

1.65V to 3.6V digital interface supply

I²S/TDM-compatible digital audio bus

30-bump, 2.2mm x 2.7mm, 0.4mm pitch WLP package