WM8731 / WM8731L
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Portable Internet Audio CODEC with Headphone Driver
and Programmable Sample Rates
DESCRIPTION FEATURES
Highly Efficient Headphone Driver
The WM8731 or WM8731L (WM8731/L) are low power
stereo CODECs with an integrated headphone driver. The Audio Performance
WM8731/L is designed specifically for portable MP3 audio - ADC SNR 90dB (A weighted) at 3.3V, 85dB at 1.8V
and speech players and recorders. The WM8731 is also
- DAC SNR 100dB (A weighted) at 3.3V, 95dB at 1.8V
ideal for MD, CD-RW machines and DAT recorders.
Low Power
- Playback only 22mW, 8mW (L Variant)
Stereo line and mono microphone level audio inputs are
- Analogue Pass Through 12mW, 3.5mW (L variant)
provided, along with a mute function, programmable line
- 1.42 3.6V Digital Supply Operation
level volume control and a bias voltage output suitable for
an electret type microphone. - 2.7 3.6V Analogue Supply Operation
- 1.8 3.6V Analogue Supply Operation (L Variant)
Stereo 24-bit multi-bit sigma delta ADCs and DACs are used
ADC and DAC Sampling Frequency: 8kHz 96kHz
with oversampling digital interpolation and decimation filters.
Selectable ADC High Pass Filter
Digital audio input word lengths from 16-32 bits and
2 or 3-Wire MPU Serial Control Interface
sampling rates from 8kHz to 96kHz are supported.
Programmable Audio Data Interface Modes
Stereo audio outputs are buffered for driving headphones 2
- I S, Left, Right Justified or DSP
from a programmable volume control, line level outputs are
- 16/20/24/32 bit Word Lengths
also provided along with anti-thump mute and power
- Master or Slave Clocking Mode
up/down circuitry.
Microphone Input and Electret Bias with Side Tone Mixer
The device is controlled via a 2 or 3 wire serial interface.
Available in 28-lead SSOP or 28-lead QFN package
The interface provides access to all features including
volume controls, mutes, de-emphasis and extensive power
APPLICATIONS
management facilities. The device is available in a small 28-
Portable MP3 Players and Recorders
lead SSOP package or the smaller 28 lead quad flat
leadless package (QFN). CD and Minidisc Recorders
PDAs / smartphones
BLOCK DIAGRAM
AVDD
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CONTROL INTERFACE
WM8731
VMID
HPVDD
Bypass
MUTE
HPGND
AGND
ATTEN /
+6 to -73 dB
MUTE
1 dB Steps
Side Tone
VOL / H/P
MICBIAS
RHPOUT
DRIVER
MUTE
RLINEIN VOL MUTE
MUX ADC DAC MUTE
MUTE
+ 12 to -34.5dB , 1.5dB
Steps
ROUT
0dB / DIGITAL
MICIN
20 dB
FILTERS
LOUT
MUTE
MUX DAC MUTE
ADC
VOL MUTE
LLINEIN
VOL / H/P
LHPOUT
+ 12 to -34.5dB , 1.5dB MUTE DRIVER
Steps Side Tone
+6 to -73 dB
ATTEN /
1 dB Steps
MUTE
MUTE
CLKIN CLKOUT
DIGTAL AUDIO INTERFACE Bypass
OSC DIVIDER DIVIDER
( Div x 1 , x2) ( Div x 1 , x2)
Production Data, October 2012, Rev 4.9
WOLFSON MICROELECTRONICS plc
Copyright 2012 Wolfson Microelectronics plc
XTO
XTI/MCLK
CLKOUT
DACDAT
CSB
DACLRC SDIN
SCLK
BCLK
MODE
ADCLRC
ADCDAT
DCVDD
DBVDD
DGNDWM8731 / WM8731L Production Data
TABLE OF CONTENTS
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
PD, Rev 4.9, October 2012
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