WM8737L
Stereo ADC with Microphone Preamplifier
DESCRIPTION
FEATURES
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.
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SNR 95dB (‘A’ weighted @ 3.3V, 48kHz, normal power
mode)
THD –90dB (at –0.5dB, 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
- 8mW at AVDD = 1.8V (stereo, mic preamps off)
- 18.5mW 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
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.
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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.
APPLICATIONS
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Memory Audio / Voice Recorders
Minidisc Recorders
Portable Digital Music Systems
BLOCK DIAGRAM
LACOUT
LACIN
BYPASS
DGND
DCVDD
DBVDD
LPGA
DC MEASUREMENT
LINPUT1
LINPUT2
LINPUT3
DIGITAL
FILTER
AUDIO
INTERFACE
LINSEL
ADC
VREF
LMICBOOST
W
ANALOGUE
MONO MIX
VREF
VREF
13/18/28/33 dB
ALC
CONTROLS
PGA GAIN
(L+R)/2
MONO
MIX
ADCDAT
ADCLRC
BCLK
VREF
WM8737L
RMICBOOST
VREF
ADC
13/18/28/33 dB
DIGITAL
FILTER
CLOCK
CIRCUITRY
MCLK
RINSEL
VREF
RINPUT3
RINPUT2
RINPUT1
MICBIAS
WOLFSON MICROELECTRONICS plc
www.wolfsonmicro.com
50K
AGND
VMID
AVDD
VREF
RACIN
VREFP
VREFN
RACOUT
50K
RPGA
MODE
SCLK
SDIN
CSB
BYPASS
DC MEASUREMENT
CONTROL
INTERFACE
MVDD
Product Preview, June 2003, Rev 1.7
Copyright 2003 Wolfson Microelectronics plc
