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24-Bit, 192kHz Stereo ADC
DESCRIPTION
The WM8781 is a high performance, low cost stereo audio
ADC designed for recordable media applications.
The device offers stereo line level inputs along with two
control input pins (FORMAT, IWL) to allow operation of the
audio interface in three industry standard modes. An
internal op-amp is integrated on the front end of the chip to
accommodate analogue input signals greater than 1V
rms
.
The device also has a high pass filter to remove residual
DC offsets.
WM8781 offers Master or Slave mode clocking schemes.
A control input pin M/S is used to allow Slave mode
operation or Master mode operation. A stereo 24-bit multi-
bit sigma-delta ADC is used with 128x, 64x or 32x over-
sampling, according to sample rate. Digital audio output
word lengths from 16-24 bits and sampling rates from
8kHz to 192kHz are supported.
The device is a hardware controlled device and is supplied
in a 20-lead SSOP or 20-lead TSSOP package.
WM8781
FEATURES
•
•
•
•
•
•
•
•
SNR 102dB (‘A’ weighted @ 48kHz)
THD -90dB (at –1dB)
Sampling Frequency: 8 – 192kHz
Master or Slave Clocking Mode
System Clock (MCLK): 128fs, 192fs, 256fs, 384fs, 512fs,
768fs
Audio Data Interface Modes
- 16-24 bit I
2
S, 16-24 bit Left, 16-24 bit Right Justified
Supply Voltages
- Analogue 2.7 to 5.5V
- Digital core: 2.7V to 3.6V
20-lead SSOP or 20-lead TSSOP package
APPLICATIONS
•
•
•
•
Recordable DVD Players
Personal Video Recorders
STB
Studio Audio Processing Equipment
BLOCK DIAGRAM
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Production Data, July 2008, Rev 4.4
Copyright
©2008
Wolfson Microelectronics plc
WM8781
TABLE OF CONTENTS
Production Data
DESCRIPTION .......................................................................................................1
FEATURES.............................................................................................................1
APPLICATIONS .....................................................................................................1
BLOCK DIAGRAM .................................................................................................1
TABLE OF CONTENTS .........................................................................................2
PIN CONFIGURATION...........................................................................................3
ORDERING INFORMATION ..................................................................................3
ABSOLUTE MAXIMUM RATINGS.........................................................................5
THERMAL PERFORMANCE .................................................................................5
RECOMMENDED OPERATING CONDITIONS .....................................................5
ELECTRICAL CHARACTERISTICS ......................................................................6
TERMINOLOGY............................................................................................................. 7
SIGNAL TIMING REQUIREMENTS .......................................................................8
DEVICE DESCRIPTION.......................................................................................10
INTRODUCTION.......................................................................................................... 10
ADC ............................................................................................................................. 10
ADC DIGITAL FILTER ................................................................................................. 10
DIGITAL AUDIO INTERFACE...................................................................................... 11
POWER DOWN CONTROL......................................................................................... 14
POWER ON RESET .................................................................................................... 14
DIGITAL FILTER CHARACTERISTICS ...............................................................16
ADC FILTER RESPONSES ......................................................................................... 16
ADC HIGH PASS FILTER............................................................................................ 17
APPLICATIONS INFORMATION .........................................................................18
RECOMMENDED EXTERNAL COMPONENTS........................................................... 18
RECOMMENDED EXTERNAL COMPONENTS VALUES............................................ 18
PACKAGE DIAGRAM - SSOP .............................................................................19
PACKAGE DIAGRAM – TSSOP ..........................................................................20
IMPORTANT NOTICE ..........................................................................................21
ADDRESS:................................................................................................................... 21
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Production Data
WM8781
PIN CONFIGURATION
MCLK
DOUT
LRCLK
DGND
DVDD
BCLK
IWL
FSAMPEN
FORMAT
VMID
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
M/S
AINL
AINOPL
COM
AINR
AINOPR
AGND
AVDD
VREFP
VREFGND
ORDERING INFORMATION
DEVICE
WM8781GEDS/V
WM8781GEDS/RV
WM8781GEDT
WM8781GEDT/R
Note:
Reel quantity = 2,000
TEMPERATURE
RANGE
-25°C to +85°C
-25°C to +85°C
-25°C to +85°C
-25°C to +85°C
PACKAGE
20-lead SSOP
(Pb-free)
20-lead SSOP
(Pb-free, tape and reel)
20-lead TSSOP
(Pb-free)
20-lead TSSOP
(Pb-free, tape and reel)
MOISTURE SENSITIVITY
LEVEL
MSL3
MSL3
MSL1
MSL1
PEAK SOLDERING
TEMPERATURE
260
o
C
260
o
C
260
o
C
260
o
C
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WM8781
PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6
7
NAME
MCLK
DOUT
LRCLK
DGND
DVDD
BCLK
IWL
TYPE
Digital Input
Digital Output
Digital Input / Output
Supply
Supply
Digital Input / Output
Digital Tristate Input
Master Clock
ADC Digital Audio Data
Audio Interface Left / Right Clock
Digital Negative Supply
Digital Positive Supply
Audio Interface Bit Clock
Word Length
0 = 16 bit
1 = 20 bit
Z = 24 bit
Fast Sampling Rate Enable
0 = 48kHz enable
1 = 96kHz enable
Z = 192kHz enable
Audio Mode Select
0 = RJ
1 = LJ
Z = I2S
Midrail Voltage Decoupling Capacitor
Negative Supply and Substrate Connection
DESCRIPTION
Production Data
8
FSAMPEN
Digital Tristate Input
9
FORMAT
Digital Tristate Input
10
11
12
13
14
15
16
17
18
19
20
VMID
VREFGND
VREFP
AVDD
AGND
AINOPR
AINR
COM
AINOPL
AINL
M/S
Analogue Output
Supply
Analogue Output
Supply
Supply
Analogue Output
Analogue Input
Analogue Input
Analogue Output
Analogue Input
Digital Input
Positive Reference Voltage Decoupling Pin; 10uF external decoupling
Analogue Positive Supply
Analogue Negative Supply and Substrate Connection
Right Channel Internal Op-Amp Output
Right Channel Input
Common mode high impedance input should be set to midrail.
Left Channel Internal Op-Amp Output
Left Channel Input
Interface Mode Select
0 = Slave mode (128fs, 192fs, 256fs, 384fs, 512fs, 768fs)
1 = Master mode (384fs, 192fs)
(fs=word clock frequency)
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Production Data
WM8781
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously
operating at or beyond these limits. Device functional operating limits and guaranteed performance specifications are given
under Electrical Characteristics at the test conditions specified.
ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible
to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage
of this device.
Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage
conditions prior to surface mount assembly. These levels are:
MSL1 = unlimited floor life at <30°C / 85% Relative Humidity. Not normally stored in moisture barrier bag.
MSL2 = out of bag storage for 1 year at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag.
MSL3 = out of bag storage for 168 hours at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag.
The Moisture Sensitivity Level for each package type is specified in Ordering Information.
CONDITION
Digital supply voltage
Analogue supply voltage
Voltage range digital inputs
Voltage range analogue inputs
Ambient temperature (supplies applied)
Storage temperature after soldering
Pb free package body temperature (reflow 10 seconds)
Package body temperature (soldering 2 minutes)
Notes
1.
Analogue and digital grounds must always be within 0.3V of each other.
MIN
-0.3V
-0.3V
DGND -0.3V
AGND -0.3V
-55 C
-65°C
o
MAX
+4.5V
+7V
DVDD + 0.3V
AVDD +0.3V
+125
o
C
+150°C
+260
o
C
+183 C
o
THERMAL PERFORMANCE
PARAMETER
SSOP-20 package
Thermal resistance – junction to
ambient
TSSOP-20 package
Thermal resistance – junction to
ambient
Notes
1.
2.
Figure given for package mounted on 4-layer FR4 according to JESD51-7. (No forced air flow is assumed).
Thermal performance figures are estimated.
SYMBOL
TEST CONDITIONS
MIN
TYP
81
See note 1
72
See note 1
MAX
UNIT
°C/W
R
θJA
R
θJA
°C/W
RECOMMENDED OPERATING CONDITIONS
PARAMETER
Digital supply range
Analogue supply range
Ground
Operating temperature range
Notes
1.
Digital supply DVDD must never be more than 0.3V greater than AVDD.
SYMBOL
DVDD
AVDD
DGND,AGND
T
A
-25°C
TEST CONDITIONS
MIN
2.7
2.7
0
+85°C
TYP
MAX
3.6
5.5
UNIT
V
V
V
V
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