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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
WM8731 / WM8731L
TABLE OF CONTENTS
Production Data
DESCRIPTION ....................................................................................................... 1
FEATURES ............................................................................................................ 1
APPLICATIONS..................................................................................................... 1
BLOCK DIAGRAM ................................................................................................ 1
PIN CONFIGURATION - 28 PIN SSOP ................................................................ 3
ORDERING INFORMATION .................................................................................. 3
PIN CONFIGURATION – 28 PIN QFN................................................................... 4
ORDERING INFORMATION .................................................................................. 4
PIN DESCRIPTION ................................................................................................ 5
ABSOLUTE MAXIMUM RATINGS ........................................................................ 6
RECOMMENDED OPERATING CONDITIONS – WM8731 .................................. 6
RECOMMENDED OPERATING CONDITIONS – WM8731L ................................ 6
ELECTRICAL CHARACTERISTICS – WM8731 ................................................... 7
TERMINOLOGY .............................................................................................................. 9
POWER CONSUMPTION – WM8731.................................................................. 10
ELECTRICAL CHARACTERISTICS – WM8731L ............................................... 11
TERMINOLOGY ............................................................................................................ 13
POWER CONSUMPTION – WM8731L ............................................................... 14
MASTER CLOCK TIMING ................................................................................... 15
DIGITAL AUDIO INTERFACE – MASTER MODE ........................................................ 16
DIGITAL AUDIO INTERFACE – SLAVE MODE ............................................................ 17
MPU INTERFACE TIMING ............................................................................................ 18
DEVICE DESCRIPTION ...................................................................................... 20
INTRODUCTION ........................................................................................................... 20
AUDIO SIGNAL PATH ................................................................................................... 21
DEVICE OPERATION ................................................................................................... 34
AUDIO DATA SAMPLING RATES ................................................................................ 41
ACTIVATING DSP AND DIGITAL AUDIO INTERFACE ................................................ 45
SOFTWARE CONTROL INTERFACE........................................................................... 45
POWER DOWN MODES ............................................................................................... 47
REGISTER MAP ............................................................................................................ 49
DIGITAL FILTER CHARACTERISTICS .............................................................. 54
TERMINOLOGY ............................................................................................................ 55
DAC FILTER RESPONSES ................................................................................. 56
ADC FILTER RESPONSES ................................................................................. 57
ADC HIGH PASS FILTER ............................................................................................. 58
DIGITAL DE-EMPHASIS CHARACTERISTICS .................................................. 58
DIGITAL DE-EMPHASIS CHARACTERISTICS .................................................. 59
APPLICATIONS INFORMATION ........................................................................ 60
RECOMMENDED EXTERNAL COMPONENTS ........................................................... 60
MINIMISING POP NOISE AT THE ANALOGUE OUTPUTS ......................................... 61
PACKAGE DIMENSIONS - SSOP....................................................................... 62
PACKAGE DIMENSIONS - QFN ......................................................................... 63
IMPORTANT NOTICE ......................................................................................... 64
ADDRESS: .................................................................................................................... 64
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PD, Rev 4.9, October 2012
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WM8731 / WM8731L
PIN CONFIGURATION - 28 PIN SSOP
DBVDD
CLKOUT
BCLK
DACDAT
DACLRC
ADCDAT
ADCLRC
HPVDD
LHPOUT
RHPOUT
HPGND
LOUT
ROUT
AVDD
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DGND
DCVDD
XTO
XTI/MCLK
SCLK
SDIN
CSB
MODE
LLINEIN
RLINEIN
MICIN
MICBIAS
VMID
AGND
Production Data
ORDERING INFORMATION
DEVICE
TEMPERATURE
RANGE
AVDD
RANGE
PACKAGE
MOISTURE
SENSITIVITY LEVEL
PEAK SOLDERING
TEMPERATURE
WM8731SEDS/V
-40 to +85 C
o
2.7 to 3.6V
28-lead SSOP
(Pb-free)
28-lead SSOP
MSL3
260°C
WM8731SEDS/RV
Note:
Reel quantity = 2,000
-40 to +85 C
o
2.7 to 3.6V
(Pb-free,
tape and reel)
MSL3
260°C
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PD, Rev 4.9, October 2012
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WM8731 / WM8731L
PIN CONFIGURATION – 28 PIN QFN
Production Data
TOP VIEW
ORDERING INFORMATION
DEVICE
TEMPERATURE
RANGE
-40 to +85 C
o
AVDD
RANGE
1.8 to 3.6V
PACKAGE
28-lead QFN
(Pb-free)
28-lead QFN
MOISTURE
SENSITIVITY LEVEL
MSL1
PEAK SOLDERING
TEMPERATURE
260°C
WM8731CLSEFL
WM8731CLSEFL/R
-40 to +85 C
o
1.8 to 3.6V
(Pb-free,
tape and reel)
28-lead QFN
(Pb-free)
28-lead QFN
MSL1
260°C
WM8731CSEFL
-40 to +85 C
o
2.7 to 3.6V
MSL1
260°C
WM8731CSEFL/R
Note:
Reel quantity = 3,500
-40 to +85 C
o
2.7 to 3.6V
(Pb-free,
tape and reel)
MSL1
260°C
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PD, Rev 4.9, October 2012
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WM8731 / WM8731L
PIN DESCRIPTION
28 PIN
SSOP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Note:
1.
2.
Pull Up/Down only present when Control Register Interface ACTIVE=0 to conserve power.
It is recommended that the QFN ground paddle is connected to analogue ground on the application PCB.
28 PIN
QFN
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
1
2
3
4
DBVDD
CLKOUT
BCLK
DACDAT
DACLRC
ADCDAT
ADCLRC
HPVDD
LHPOUT
RHPOUT
HPGND
LOUT
ROUT
AVDD
AGND
VMID
MICBIAS
MICIN
RLINEIN
LLINEIN
MODE
CSB
SDIN
SCLK
XTI/MCLK
XTO
DCVDD
DGND
Supply
Digital Output
Digital Input/Output
Digital Input
Digital Input/Output
Digital Output
Digital Input/Output
Supply
Analogue Output
Analogue Output
Ground
Analogue Output
Analogue Output
Supply
Ground
Analogue Output
Analogue Output
Analogue Input
Analogue Input
Analogue Input
Digital Input
Digital Input
Digital Input/Output
Digital Input
Digital Input
Digital Output
Supply
Ground
Digital Buffers VDD
Buffered Clock Output
NAME
TYPE
DESCRIPTION
Production Data
Digital Audio Bit Clock, Pull Down, (see Note 1)
DAC Digital Audio Data Input
DAC Sample Rate Left/Right Clock, Pull Down (see Note 1)
ADC Digital Audio Data Output
ADC Sample Rate Left/Right Clock, Pull Down (see Note 1)
Headphone VDD
Left Channel Headphone Output
Right Channel Headphone Output
Headphone GND
Left Channel Line Output
Right Channel Line Output
Analogue VDD
Analogue GND
Mid-rail reference decoupling point
Electret Microphone Bias
Microphone Input (AC coupled)
Right Channel Line Input (AC coupled)
Left Channel Line Input (AC coupled)
Control Interface Selection, Pull Up (see Note 1)
3-Wire MPU Chip Select/ 2-Wire MPU interface address
selection, active low, Pull up (see Note 1)
3-Wire MPU Data Input / 2-Wire MPU Data Input
3-Wire MPU Clock Input / 2-Wire MPU Clock Input
Crystal Input or Master Clock Input (MCLK)
Crystal Output
Digital Core VDD
Digital GND
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PD, Rev 4.9, October 2012
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