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DESCRIPTION
The WM8731 or WM8731L (WM8731/L) are low power
stereo CODECs with an integrated headphone driver. The
WM8731/L is designed specifically for portable MP3 audio
and speech players and recorders. The WM8731 is also
ideal for MD, CD-RW machines and DAT recorders.
Stereo line and mono microphone level audio inputs are
provided, along with a mute function, programmable line
level volume control and a bias voltage output suitable for
an electret type microphone.
Stereo 24-bit multi-bit sigma delta ADCs and DACs are used
with oversampling digital interpolation and decimation filters.
Digital audio input word lengths from 16-32 bits and
sampling rates from 8kHz to 96kHz are supported.
Stereo audio outputs are buffered for driving headphones
from a programmable volume control, line level outputs are
also provided along with anti-thump mute and power
up/down circuitry.
The device is controlled via a 2 or 3 wire serial interface.
The interface provides access to all features including
volume controls, mutes, de-emphasis and extensive power
management facilities. The device is available in a small 28-
lead SSOP package or the smaller 28 lead quad flat
leadless package (QFN).
WM8731 / WM8731L
Portable Internet Audio CODEC with Headphone Driver
and Programmable Sample Rates
FEATURES
Highly Efficient Headphone Driver
Audio Performance
- ADC SNR 90dB (‘A’ weighted) at 3.3V, 85dB at 1.8V
-
DAC SNR 100dB
(‘A’ weighted) at
3.3V, 95dB at 1.8V
Low Power
- Playback only 22mW, 8mW (‘L’ Variant)
- Analogue Pass Through 12mW, 3.5mW (‘L’ variant)
- 1.42 – 3.6V Digital Supply Operation
- 2.7 – 3.6V Analogue Supply Operation
- 1.8 – 3.6V Analogue Supply Operation (‘L’ Variant)
ADC and DAC Sampling Frequency: 8kHz – 96kHz
Selectable ADC High Pass Filter
2 or 3-Wire MPU Serial Control Interface
Programmable Audio Data Interface Modes
2
- I S, Left, Right Justified or DSP
- 16/20/24/32 bit Word Lengths
- Master or Slave Clocking Mode
Microphone Input and Electret Bias with Side Tone Mixer
Available in 28-lead SSOP or 28-lead QFN package
APPLICATIONS
MODE
SCLK
Portable MP3 Players and Recorders
CD and Minidisc Recorders
PDAs / smartphones
BLOCK DIAGRAM
CSB
AVDD
CONTROL INTERFACE
VMID
Bypass
AGND
MUTE
ATTEN /
MUTE
SDIN
W
WM8731
HPVDD
HPGND
+ 6 to - 73 dB
1 dB Steps
VOL /
MUTE
H /P
DRIVER
MICBIAS
RLINEIN
VOL
MUTE
MUTE
MUX
Side Tone
ADC
DAC
RHPOUT
+ 12 to - 34 .5 dB , 1 .5 dB
Steps
MICIN
0 dB /
20 dB
MUTE
DIGITAL
FILTERS
MUTE
ROUT
LOUT
MUX
ADC
DAC
MUTE
VOL /
MUTE
H/P
DRIVER
LLINEIN
VOL
MUTE
+ 12 to - 34 .5 dB , 1 . 5 dB
Steps
LHPOUT
Side Tone
ATTEN /
MUTE
MUTE
+ 6 to - 73 dB
1 dB Steps
OSC
CLKIN
DIVIDER
( Div x 1 , x 2)
CLKOUT
DIVIDER
( Div x 1 , x 2 )
DIGTAL AUDIO INTERFACE
Bypass
DACDAT
XTI/MCLK
ADCDAT
DACLRC
ADCLRC
DCVDD
CLKOUT
DBVDD
WOLFSON MICROELECTRONICS plc
Production Data, October 2012, Rev 4.9
Copyright
2012
Wolfson Microelectronics plc
DGND
BCLK
XTO
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
