WM8737: Stereo ADC with microphone preamp


Description

The WM8737L is a low power stereo audio ADC designed specifically for portable applications such as minidisc and memory audio / voice recorders.

The device offers three sets of stereo inputs, which can be configured for line-level signals, for internal or table-top microphones, or for DC measurement (battery monitor). A programmable gain amplifier can be used for automatic level control (ALC) with user programmable hold, attack and decay times. The device also has a selectable high pass filter to remove residual DC offsets.

If the signal source is mono, the WM8737L can run in mono mode, saving power. It can also mix two channels to mono, either in the analogue or the digital domain.

Master or slave mode clocking schemes are offered. Stereo 24-bit multi-bit sigma-delta ADCs are used with digital audio output word lengths from 16-32 bits, and sampling rates from 8kHz to 96kHz supported.

The device is controlled via a 2 or 3 wire serial interface. The interface provides access to all features including gain controls, analogue or digital mono mixing, and power management facilities. The device is supplied in a leadless 5x5mm QFN package.

Features

  • SNR 97dB (A weighted @ 3.3V, 48kHz, normal power mode)
  • THD -84dB (at -1dB, 3.3V, normal power mode)
  • Complete Stereo / Mono Microphone Interface
  • Programmable microphone preamp;
  • Automatic Level Control;
  • Low-noise microphone bias voltage
  • Configurable Power / Performance Low Power Mode
  • 8.5mW at AVDD = 1.8V (stereo, mic preamps off)
  • 20mW at AVDD = 3.3V (stereo, mic preamps off)
  • Low Supply Voltages
  • Analogue 1.8V to 3.6V 
  • Digital core: 1.42V to 3.6V 
  • Digital I/O: 1.8V to 3.6V
  • 256fs / 384fs or USB master clock rates: 12MHz, 24MHz
  • Audio sample rates: 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48, 88.2, 96kHz generated internally from master clock 
  • 32-pin QFN package, 5 x 5 x 0.9mm