Wolfson WM8750L

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WM8750L
Stereo CODEC for Portable Audio Applications
DESCRIPTION
FEATURES
The WM8750L is a low power, high quality stereo CODEC
designed for portable digital audio applications.
•
•
•
The device integrates complete interfaces to stereo or mono
microphones and a stereo headphone. External component
requirements are drastically reduced as no separate
microphone or headphone amplifiers are required.
Advanced on-chip digital signal processing performs
graphic equaliser, 3-D sound enhancement and automatic
level control for the microphone or line input.
The WM8750L can operate as a master or a slave, with
various master clock frequencies including 12 or 24MHz for
USB devices, or standard 256fs rates like 12.288MHz and
24.576MHz. Different audio sample rates such as 96kHz,
48kHz, 44.1kHz are generated directly from the master
clock without the need for an external PLL.
The WM8750L operates at supply voltages down to 1.8V,
although the digital core can operate at voltages down to
1.42V to save power, and the maximum for all supplies is
3.6 Volts. Different sections of the chip can also be powered
down under software control.
The WM8750L is supplied in a very small and thin 5x5mm
QFN package, ideal for use in hand-held and portable
systems.
•
•
•
•
•
•
•
•
•
DAC SNR 98dB (‘A’ weighted), THD –84dB at 48kHz, 3.3V
ADC SNR 95dB (‘A’ weighted), THD -82dB at 48kHz, 3.3V
Complete Stereo / Mono Microphone Interface
- Programmable ALC / Noise Gate
On-chip 400mW BTL Speaker Driver (mono)
On-chip Headphone Driver
- >40mW output power on 16Ω / 3.3V
- THD –80dB at 20mW, SNR 90dB with 16Ω load
- No DC blocking capacitors required (capless mode)
Separately mixed mono output
Digital Graphic Equaliser
Low Power
- 7mW stereo playback (1.8V / 1.5V supplies)
- 14mW record & playback (1.8V / 1.5V supplies)
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, 16, 22.05, 24, 32, 44.1, 48,
88.2, 96kHz generated internally from master clock
5x5x0.9mm QFN package
APPLICATIONS
•
•
•
•
MP3 Player / Recorder
AAC/WMA/Multi-Format Player / Recorder
Minidisc Player / Recorder
Portable Digital Music Systems
BLOCK DIAGRAM
WOLFSON MICROELECTRONICS plc
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Production Data, August 2005, Rev 4.2
Copyright 2005 Wolfson Microelectronics plc
WM8750L
Production Data
TABLE OF CONTENTS
DESCRIPTION .......................................................................................................1
FEATURES.............................................................................................................1
APPLICATIONS .....................................................................................................1
BLOCK DIAGRAM .................................................................................................1
TABLE OF CONTENTS .........................................................................................2
PIN CONFIGURATION...........................................................................................4
ORDERING INFORMATION ..................................................................................4
PIN DESCRIPTION ................................................................................................5
ABSOLUTE MAXIMUM RATINGS.........................................................................6
RECOMMENDED OPERATION CONDITIONS .....................................................6
ELECTRICAL CHARACTERISTICS ......................................................................7
OUTPUT PGA’S LINEARITY ......................................................................................... 9
HEADPHONE OUTPUT THD VERSUS POWER......................................................... 10
SPEAKER THD AND NOISE VERSUS POWER ......................................................... 11
POWER CONSUMPTION ....................................................................................12
SIGNAL TIMING REQUIREMENTS .....................................................................13
SYSTEM CLOCK TIMING............................................................................................ 13
AUDIO INTERFACE TIMING – MASTER MODE ......................................................... 13
AUDIO INTERFACE TIMING – SLAVE MODE ............................................................ 14
INTERNAL POWER ON RESET CIRCUIT ..........................................................17
DEVICE DESCRIPTION.......................................................................................18
INTRODUCTION.......................................................................................................... 18
INPUT SIGNAL PATH.................................................................................................. 18
AUTOMATIC LEVEL CONTROL (ALC) ....................................................................... 25
OUTPUT SIGNAL PATH.............................................................................................. 29
ANALOGUE OUTPUTS ............................................................................................... 34
ENABLING THE OUTPUTS ......................................................................................... 36
HEADPHONE SWITCH ............................................................................................... 36
THERMAL SHUTDOWN .............................................................................................. 38
HEADPHONE OUTPUT ............................................................................................... 38
DIGITAL AUDIO INTERFACE...................................................................................... 39
AUDIO INTERFACE CONTROL .................................................................................. 43
CLOCKING AND SAMPLE RATES .............................................................................. 45
CONTROL INTERFACE .............................................................................................. 47
POWER SUPPLIES ..................................................................................................... 48
POWER MANAGEMENT ............................................................................................. 48
REGISTER MAP...................................................................................................51
DIGITAL FILTER CHARACTERISTICS ...............................................................52
TERMINOLOGY........................................................................................................... 52
DAC FILTER RESPONSES ......................................................................................... 53
ADC FILTER RESPONSES ......................................................................................... 54
DE-EMPHASIS FILTER RESPONSES ........................................................................ 55
HIGHPASS FILTER ..................................................................................................... 56
APPLICATIONS INFORMATION .........................................................................57
RECOMMENDED EXTERNAL COMPONENTS........................................................... 57
LINE INPUT CONFIGURATION................................................................................... 58
MICROPHONE INPUT CONFIGURATION .................................................................. 58
MINIMISING POP NOISE AT THE ANALOGUE OUTPUTS ........................................ 58
POWER MANAGEMENT EXAMPLES ......................................................................... 59
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WM8750L
IMPORTANT NOTICE ..........................................................................................61
ADDRESS.................................................................................................................... 61
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PIN CONFIGURATION
ORDERING INFORMATION
ORDER CODE
TEMPERATURE
RANGE
PACKAGE
MOISTURE
PEAK SOLDERING
SENSITIVITY LEVEL
TEMPERATURE
WM8750LSEFL
-25°C to +85°C
32-lead QFN (5x5x0.9mm)
(Pb-free)
MSL1
260oC
WM8750LSEFL/R
-25°C to +85°C
32-lead QFN (5x5x0.9mm)
(Pb-free, tape and reel)
MSL1
260oC
Note:
Reel quantity = 3500
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PIN DESCRIPTION
PIN NO
NAME
1
MCLK
2
3
TYPE
DESCRIPTION
Digital Input
Master Clock
DCVDD
Supply
Digital Core Supply
DBVDD
Supply
Digital Buffer (I/O) Supply
4
DGND
Supply
Digital Ground (return path for both DCVDD and DBVDD)
5
BCLK
Digital Input / Output
Audio Interface Bit Clock
6
DACDAT
Digital Input
DAC Digital Audio Data
7
DACLRC
Digital Input / Output
Audio Interface Left / Right Clock/Clock Out
8
ADCDAT
Digital Output
ADC Digital Audio Data
9
ADCLRC
Digital Input / Output
Audio Interface Left / Right Clock
10
MONOOUT
Analogue Output
Mono Output
11
OUT3
Analogue Output
Analogue Output 3 (can be used as Headphone Pseudo Ground)
12
ROUT1
Analogue Output
Right Output 1 (Line or Headphone)
13
LOUT1
Analogue Output
Left Output 1 (Line or Headphone)
14
HPGND
Supply
Supply for Analogue Output Drivers (LOUT1/2, ROUT1/2)
15
ROUT2
Analogue Output
Right Output 1 (Line or Headphone or Speaker)
16
LOUT2
Analogue Output
Left Output 1 (Line or Headphone or Speaker)
17
HPVDD
Supply
Supply for Analogue Output Drivers (LOUT1/2, ROUT1/2,
MONOUT)
18
AVDD
Supply
Analogue Supply
19
AGND
Supply
Analogue Ground (return path for AVDD)
20
VREF
Analogue Output
Reference Voltage Decoupling Capacitor
21
VMID
Analogue Output
Midrail Voltage Decoupling Capacitor
22
MICBIAS
Analogue Output
Microphone Bias
23
RINPUT3 /
HPDETECT
Analogue Input
Right Channel Input 3 or Headphone Plug-in Detection
24
LINPUT3
Analogue Input
Left Channel Input 3
25
RINPUT2
Analogue Input
Right Channel Input 2
26
LINPUT2
Analogue Input
Left Channel Input 2
27
RINPUT1
Analogue Input
Right Channel Input 1
28
LINPUT1
Analogue Input
Left Channel Input 1
29
MODE
Digital Input
Control Interface Selection
30
CSB
Digital Input
Chip Select / Device Address Selection
31
32
SDIN
SCLK
Digital Input/Output
Digital Input
Control Interface Data Input / 2-wire Acknowledge output
Control Interface Clock Input
Note:
It is recommended that the QFN ground paddle should be connected to analogue ground on the application PCB.
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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
MIN
MAX
-0.3V
+3.63V
Voltage range digital inputs
DGND -0.3V
DBVDD +0.3V
Voltage range analogue inputs
AGND -0.3V
AVDD +0.3V
Supply voltages
Operating temperature range, TA
-25°C
+85°C
Storage temperature after soldering
-65°C
+150°C
Notes
1.
Analogue and digital grounds must always be within 0.3V of each other.
2.
All digital and analogue supplies are completely independent from each other.
3.
DCVDD must be less than or equal to AVDD and DBVDD.
RECOMMENDED OPERATION CONDITIONS
PARAMETER
SYMBOL
MIN
TYP
MAX
Digital supply range (Core)
DCVDD
1.42
2.0
3.6
V
Digital supply range (Buffer)
DBVDD
1.7
2.0
3.6
V
AVDD, HPVDD
1.8
2.0
3.6
V
Analogue supplies range
Ground
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DGND,AGND, HPGND
0
UNIT
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ELECTRICAL CHARACTERISTICS
Test Conditions
DCVDD = 1.5V, DBVDD = 3.3V, AVDD = HPVDD = 3.3V, TA = +25oC, 1kHz signal, fs = 48kHz, PGA gain = 0dB, 24-bit audio
data unless otherwise stated.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Analogue Inputs (LINPUT1, RINPUT1, LINPUT2, RINPUT2, LINPUT3, RINPUT3) to ADC out
Full Scale Input Signal Level
(for ADC 0dB Input at 0dB Gain)
AVDD = 3.3V
1.0
AVDD = 1.8V
0.545
L/RINPUT1 to ADC,
PGA gain = 0dB
22
L/RINPUT1 to ADC,
PGA gain = +30dB
1.5
L/RINPUT1 unused
DC Measurement
16
VINFS
Input Resistance
L/RINPUT1 unused
SNR
AVDD = 3.3V
Total Harmonic Distortion
80
AVDD = 1.8V
Dynamic Range
-60dBFs
THD
kΩ
17
Input Capacitance
Signal to Noise Ratio
(A-weighted)
V rms
10
pF
95
dB
90
90
95
dB
-1dBFs input,
AVDD = 3.3V
-82
0.008
dB
%
-1dBFs input,
AVDD = 1.8V
-74
0.02
ADC Channel Separation
1kHz signal
85
dB
Channel Matching
1kHz signal
0.2
dB
Analogue Outputs (LOUT1/2, ROUT1/2, MONOOUT)
0dB Full scale output voltage
AVDD/3.3
Mute attenuation
Channel Separation
Vrms
dB
1kHz, full scale signal
90
MONOOUT pin
81
analogue in
to analogue out
85
dB
98
dB
DAC to Line-Out (L/ROUT2 with 10kΩ
Ω / 50pF load)
Signal to Noise Ratio
(A-weighted)
SNR
Total Harmonic Distortion
THD
AVDD=3.3V
90
AVDD=1.8V
Channel Separation
93
AVDD=3.3V
-84
AVDD=1.8V
-80
1kHz signal
100
dB
dB
Headphone Output (LOUT1/ROUT1, using capacitors)
Output Power per channel
PO
Total Harmonic Distortion
THD
Signal to Noise Ratio
(A-weighted)
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SNR
Output power is very closely correlated with THD; see below.
HPVDD=1.8V, RL=32Ω
PO=5mW
0.016
-76
HPVDD=1.8V, RL=16Ω
PO=5mW
0.022
-73
HPVDD=3.3V, RL=32Ω,
PO=20mW
0.013
-78
HPVDD=3.3V, RL=16Ω,
PO=20mW
0.018
-75
HPVDD = 3.3V
HPVDD = 1.8V
92
96
%
dB
dB
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Test Conditions
DCVDD = 1.5V, DBVDD = 3.3V, AVDD = HPVDD = 3.3V, TA = +25oC, 1kHz signal, fs = 48kHz, PGA gain = 0dB, 24-bit audio
data unless otherwise stated.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Speaker Output (LOUT2/ROUT2 with 8Ω
Ω bridge tied load, ROUT2INV=1)
Output Power at 1% THD
Abs. Max Power Ouptut
PO
THD = 1%
POmax
330
mW (rms)
500
mW (rms)
Total Harmonic Distortion
THD
Po=200mW, RL=8Ω,
HPVDD=3.3V
-63
0.07
dB
%
Signal to Noise Ratio
(A-weighted)
SNR
HPVDD=3.3V, RL=8Ω
95
dB
Analogue Reference Levels
Midrail Reference Voltage
VMID
–3%
AVDD/2
+3%
V
Buffered Reference Voltage
VREF
–3%
AVDD/2
+3%
V
–5%
0.9×AVDD
+ 5%
V
3
mA
Microphone Bias
Bias Voltage
VMICBIAS
Bias Current Source
IMICBIAS
Output Noise Voltage
Vn
3mA load current
1K to 20kHz
15
nV/√Hz
Digital Input / Output
Input HIGH Level
VIH
Input LOW Level
VIL
Output HIGH Level
VOH
IOH = +1mA
Output LOW Level
VOL
IOL = -1mA
0.7×DBVDD
V
0.3×DBVDD
V
0.1×DBVDD
V
0.3×AVDD
V
0.9×DBVDD
V
HPDETECT (pin 23)
Input HIGH Level
VIH
Input LOW Level
VIL
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0.7×AVDD
V
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OUTPUT PGA’S LINEARITY
10.000
0.000
Output PGA Gains
Measured Gain [dB]
-10.000
-20.000
-30.000
LOUT1
-40.000
ROUT1
LOUT2
-50.000
ROUT2
MONOOUT
-60.000
-70.000
40
50
60
70
80
90
100
110
120
130
XXXVOL Register Setting (binary)
2.000
1.750
Output PGA Gain Step Size
Step Size [dB]
1.500
1.250
1.000
0.750
LOUT1
ROUT1
0.500
LOUT2
ROUT2
0.250
MONOOUT
0.000
40
50
60
70
80
90
100
110
120
130
XXXVOL Register Setting (binary)
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HEADPHONE OUTPUT THD VERSUS POWER
0
Headphone Pow er vs THD+N (32Ohm load)
THD+N (dB)
-20
AVDD=1.8V
-40
AVDD=1.8V, capless
AVDD=3.3V
-60
AVDD=3.3V, capless
-80
-100
0
5
10
15
20
25
30
Pow er (m W)
0
Headphone Pow er vs THD+N (16Ohm load)
THD+N (dB)
-20
AVDD=1.8V
-40
AVDD=1.8V, capless
AVDD=3.3V
-60
AVDD=3.3V, capless
-80
-100
0
10
20
30
40
50
60
Pow er (m W)
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SPEAKER THD AND NOISE VERSUS POWER
THD referenced
to 0.95Vrms
WM8750 L/ROUT2 8R BTL Speaker Load THD+NvPo
AVDD=HPVDD=DBVDD=3.3V DCVDD=1.42V
1.013kHz sinewave input signal, A-weighted
0
-10
-20
THD+N (dB)
-30
-40
-50
-60
-70
-80
-90
-100
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
500.00
Output Power (mW)
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POWER CONSUMPTION
The power consumption of the WM8750L depends on the following factors.
•
Supply voltages: Reducing the supply voltages also reduces supply currents, and therefore results in significant power
savings, especially in the digital sections of the WM8750L.
•
Operating mode: Significant power savings can be achieved by always disabling parts of the WM8750L that are not
used (e.g. mic pre-amps, unused outputs, DAC, ADC, etc.)
R24 R23
Other settings
AVDD
DCVDD
DBVDD
HPVDD
VSEL
VMIDSEL
Bit
R26 (1Ah)
VREF
AINL
AINR
ADCL
ADCR
MICB
DACL
DACR
LOUT1
ROUT1
LOUT2
ROUT2
MONO
OUT3
ADCOSR
DACOSR
R25 (19h)
Control Register
V I (mA) V I (mA) V I (mA) V I (mA)
00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11
Clocks stopped
3.3 0.0016 3.3 0.0190 3.3 0.0080 3.3 0.0002
01
2.5 0.0008 2.5 0.0170 2.5 0.0050 2.5 0.0000
00
1.8 0.0005 1.5 0.0120 1.8 0.0350 1.8 0.0000
Standby
10 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11
Interface Stopped
3.3 0.3900 3.3 0.0390 3.3 0.0080 3.3 0.0000
(500 KOhm VMID string)
01
2.5 0.2880 2.5 0.0170 2.5 0.0050 2.5 0.0000
00
1.8 0.1970 1.5 0.0120 1.8 0.0036 1.8 0.0000
Playback to Line-out
01 1 0 0 0 0 0 1 1 0 0 1 1 0 0 0 0 11
3.3 3.7310 3.3 5.6600 3.3 0.3000 3.3 0.2370
01
2.5 2.6940 2.5 3.8600 2.5 0.2200 2.5 0.2100
00
1.8 1.8820 1.5 2.1400 1.8 0.1488 1.8 0.1500
Playback to Line-out
01 1 0 0 0 0 0 1 1 1 1 0 0 0 0 0 1 11
3.3 3.5170 3.3 4.6470 3.3 0.3000 3.3 0.9500
(64x oversampling mode)
01
2.5 2.5760 2.5 3.2030 2.5 0.2200 2.5 0.6480
00
1.8 1.7760 1.5 1.7590 1.8 0.1488 1.8 0.4130
Playback to 16 Ohm Headphone 01 1 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 11
3.3 3.7260 3.3 5.6700 3.3 0.3000 3.3 0.9530
01
2.5 2.7530 2.5 3.9250 2.5 0.2200 2.5 0.6570
00
1.8 1.8900 1.5 2.1410 1.8 0.1488 1.8 0.4150
Playback to 16 Ohm Headphone 01 1 0 0 0 0 0 1 1 1 1 0 0 0 1 0 0 11 R24, OUT3SW=00 3.3 3.7060 3.3 5.6400 3.3 0.3000 3.3 1.4040
(capless mode using OUT3)
01
2.5 2.7130 2.5 3.9000 2.5 0.2200 2.5 0.9600
00
1.8 1.8870 1.5 2.1410 1.8 0.1488 1.8 0.6140
Playback to 8 Ohm BTL Speaker 01 1 0 0 0 0 0 1 1 0 0 1 1 0 0 0 0 11 R24, ROUT2INV=1 3.3 3.8820 3.3 5.6470 3.3 0.3000 3.3 0.2830
01
2.5 2.8780 2.5 3.9390 2.5 0.2200 2.5 0.2100
00
1.8 1.9800 1.5 2.1630 1.8 0.1488 1.8 0.1510
Headphone Amp
01 1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 11
Clocks Stopped
3.3 1.8400 3.3 0.0200 3.3 0.0080 3.3 0.9540
(line-in to 16 Ohm headphone)
01
2.5 1.3300 2.5 0.0190 2.5 0.0050 2.5 0.6400
00
1.8 0.9300 1.5 0.0130 1.8 0.0036 1.8 0.4100
Speaker Amp
01 1 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 11
Clocks Stopped
3.3 1.9780 3.3 0.0200 3.3 0.0080 3.3 0.3310
(line-in to 8 Ohm speaker)
01 R24, ROUT2INV=1 2.5 1.4300 2.5 0.0190 2.5 0.0050 2.5 0.2430
00
1.8 0.9860 1.5 0.0130 1.8 0.0036 1.8 0.1760
Phone Call
01 1 0 0 0 0 1 0 0 0 0 1 1 1 0 0 0 11
Clocks Stopped
3.3 2.5230 3.3 0.0370 3.3 0.0080 3.3 0.4420
(mono line-in to headphone,
01
2.5 1.8520 2.5 0.0190 2.5 0.0050 2.5 0.3200
mic to MONOOUT)
00
1.8 1.2900 1.5 0.0130 1.8 0.0036 1.8 0.2240
Record from Line-in
01 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 11
3.3 8.6600 3.3 6.5700 3.3 0.3330 3.3 0.0000
01
2.5 7.7100 2.5 4.2800 2.5 0.2320 2.5 0.0000
00
1.8 6.8000 1.5 2.2100 1.8 0.1620 1.8 0.0000
Record from Line-in
01 1 1 1 1 1 0 0 0 0 0 0 0 0 0 1 0 11
3.3 5.0720 3.3 5.9100 3.3 0.3390 3.3 0.0000
(64x oversampling mode)
01
2.5 4.2550 2.5 3.7500 2.5 0.2320 2.5 0.0000
00
1.8 3.5900 1.5 1.9100 1.8 0.1620 1.8 0.0000
Record from mono microphone 01 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 11 R32, LMICBOOST=11; 3.3 4.9330 3.3 6.5400 3.3 0.3390 3.3 0.0000
01
R23, DATSEL=01
2.5 4.2970 2.5 4.2500 2.5 0.2400 2.5 0.0000
00
1.8 3.7210 1.5 2.2200 1.8 0.1644 1.8 0.0000
Record from mono microphone 01 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 11 R32, LMICBOOST=11; 3.3 5.2900 3.3 6.5000 3.3 0.3220 3.3 0.0000
(differential)
01
R23, DATSEL=01; 2.5 4.5600 2.5 4.2700 2.5 0.2400 2.5 0.0000
00
R32, LINSEL=11
1.8 3.9000 1.5 2.2200 1.8 0.1656 1.8 0.0000
Stereo Record & Playback
01 1 1 1 1 1 1 1 1 0 0 1 1 0 0 0 0 11
3.3 11.927 3.3 10.870 3.3 0.3320 3.3 0.2820
01
2.5 10.112 2.5 7.3600 2.5 0.2340 2.5 0.2060
00
1.8 7.3910 1.5 4.0610 1.8 0.1584 1.8 0.1480
Stereo Record & Playback
01 1 1 1 1 1 1 1 1 0 0 1 1 0 0 1 1 11
3.3 8.1090 3.3 9.3300 3.3 0.3330 3.3 0.2820
(64x oversampling mode)
01
2.5 6.5500 2.5 6.3020 2.5 0.2340 2.5 0.2070
00
1.8 4.7000 1.5 3.3800 1.8 0.1584 1.8 0.1490
OFF
Tot. Power
mW
0.0950
0.0570
0.0819
1.4421
0.7750
0.3791
32.7624
17.4600
7.1354
31.0662
16.6175
6.8465
35.1417
18.8875
7.6283
36.4650
19.4825
7.9811
33.3696
18.1175
7.3481
9.3126
4.9850
2.4380
7.7121
4.2425
2.1176
9.9330
5.4900
2.7512
51.3579
30.5550
15.8466
37.3593
20.5925
9.6186
38.9796
21.9675
10.3237
39.9696
22.6750
10.6481
77.2563
44.7800
19.9468
59.5782
33.2325
14.0833
Table 1 Supply Current Consumption
Notes:
1.
All figures are at TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 12.288 MHz (256fs), with zero signal (quiescent)
2.
The power dissipated in the headphone or speaker is not included in the above table.
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SIGNAL TIMING REQUIREMENTS
SYSTEM CLOCK TIMING
tMCLKL
MCLK
tMCLKH
tMCLKY
Figure 1 System Clock Timing Requirements
Test Conditions
CLKDIV2=0, DCVDD = 1.42V, DBVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode fs = 48kHz, MCLK = 384fs, 24-bit data,
unless otherwise stated.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
System Clock Timing Information
MCLK System clock pulse width high
TMCLKL
21
ns
MCLK System clock pulse width low
TMCLKH
21
ns
MCLK System clock cycle time
TMCLKY
54
MCLK duty cycle
TMCLKDS
60:40
ns
40:60
Test Conditions
CLKDIV2=1, DCVDD = 1.42V, DBVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode fs = 48kHz, MCLK = 384fs, 24-bit data,
unless otherwise stated.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
System Clock Timing Information
MCLK System clock pulse width high
TMCLKL
10
ns
MCLK System clock pulse width low
TMCLKH
10
ns
MCLK System clock cycle time
TMCLKY
27
ns
AUDIO INTERFACE TIMING – MASTER MODE
BCLK
(Output)
tDL
ADCLRC/
DACLRC
(Outputs)
tDDA
ADCDAT
DACDAT
tDST
tDHT
Figure 2 Digital Audio Data Timing – Master Mode (see Control Interface)
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Test Conditions
DCVDD = 1.42V, DBVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs, 24-bit data, unless
otherwise stated.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
Bit Clock Timing Information
BCLK rise time (10pF load)
tBCLKR
3
ns
BCLK fall time (10pF load)
tBCLKF
3
ns
BCLK duty cycle (normal mode, BCLK = MCLK/n)
tBCLKDS
50:50
BCLK duty cycle (USB mode, BCLK = MCLK)
tBCLKDS
TMCLKDS
Audio Data Input Timing Information
ADCLRC/DACLRC propagation delay from BCLK falling edge
tDL
10
ns
ADCDAT propagation delay from BCLK falling edge
tDDA
10
ns
DACDAT setup time to BCLK rising edge
tDST
10
ns
DACDAT hold time from BCLK rising edge
tDHT
10
ns
AUDIO INTERFACE TIMING – SLAVE MODE
tBCH
tBCL
BCLK
tBCY
DACLRC/
ADCLRC
tDS
tLRH
tLRSU
DACDAT
tDD
tDH
ADCDAT
Figure 3 Digital Audio Data Timing – Slave Mode
Test Conditions
DCVDD = 1.42V, DBVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs, 24-bit data, unless
otherwise stated.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
Audio Data Input Timing Information
BCLK cycle time
tBCY
50
ns
BCLK pulse width high
tBCH
20
ns
BCLK pulse width low
tBCL
20
ns
ADCLRC/DACLRC set-up time to BCLK rising edge
tLRSU
10
ns
ADCLRC/DACLRC hold time from BCLK rising edge
tLRH
10
ns
DACDAT hold time from BCLK rising edge
tDH
10
ADCDAT propagation delay from BCLK falling edge
tDD
ns
10
ns
Note:
BCLK period should always be greater than or equal to MCLK period.
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CONTROL INTERFACE TIMING – 3-WIRE MODE
tCSL
tCSH
CSB
tCSS
tSCY
tSCH
tSCS
tSCL
SCLK
LSB
SDIN
tDSU
tDHO
Figure 4 Control Interface Timing – 3-Wire Serial Control Mode
Test Conditions
DCVDD = 1.42V, DBVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs, 24-bit data, unless
otherwise stated.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
Program Register Input Information
SCLK rising edge to CSB rising edge
tSCS
80
SCLK pulse cycle time
tSCY
200
ns
SCLK pulse width low
tSCL
80
ns
SCLK pulse width high
tSCH
80
ns
SDIN to SCLK set-up time
tDSU
40
ns
SCLK to SDIN hold time
tDHO
40
ns
CSB pulse width low
tCSL
40
ns
CSB pulse width high
tCSH
40
ns
CSB rising to SCLK rising
tCSS
40
ns
tps
0
Pulse width of spikes that will be suppressed
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5
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CONTROL INTERFACE TIMING – 2-WIRE MODE
t3
t3
t5
SDIN
t4
t6
t2
t8
SCLK
t1
t9
t7
Figure 5 Control Interface Timing – 2-Wire Serial Control Mode
Test Conditions
DCVDD = 1.42V, DBVDD = 3.3V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs, 24-bit data, unless
otherwise stated.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
Program Register Input Information
SCLK Frequency
0
400
kHz
SCLK Low Pulse-Width
t1
1.3
us
SCLK High Pulse-Width
t2
600
ns
Hold Time (Start Condition)
t3
600
ns
Setup Time (Start Condition)
t4
600
ns
Data Setup Time
t5
100
ns
SDIN, SCLK Rise Time
t6
300
ns
SDIN, SCLK Fall Time
t7
300
ns
Setup Time (Stop Condition)
t8
Data Hold Time
t9
900
ns
Pulse width of spikes that will be suppressed
tps
5
ns
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0
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INTERNAL POWER ON RESET CIRCUIT
DCVDD
AVDD
VDD
T1
Power on Reset
Circuit
Internal PORB
GND
DGND
Figure 6 Internal Power on Reset Circuit Schematic
The WM8750 includes an internal Power-On-Reset Circuit, as shown in Figure 6, which is used to
reset the digital logic into a default state after power up. The power on reset circuit is powered from
DCVDD and monitors DCVDD and AVDD. It asserts PORB low if DCVDD or AVDD are below a
minimum threshold.
Figure 7 Typical Power-Up Sequence
Figure 7 shows a typical power-up sequence. When DCVDD and AVDD rise above the minimum
thresholds, Vpord_dcvdd and Vpord_avdd, there is enough voltage for the circuit to guarantee the
Power on Reset is asserted low and the chip is held in reset. In this condition, all writes to the control
interface are ignored. When DCVDD rises to Vpor_dcvdd_on and AVDD rises to Vpor_avdd_on,
PORB is released high and all registers are in their default state and writes to the control interface
may take place. If DCVDD and AVDD rise at different rates then PORB will only be released when
DCVDD and AVDD have both exceeded the Vpor_dcvdd_on and Vpor_avdd_on thresholds.
On power down, PORB is asserted low whenever DCVDD drops below the minimum threshold
Vpor_dcvdd_off or AVDD drops below the minimum threshold Vpor_avdd_off.
SYMBOL
MIN
TYP
MAX
Vpord_dcvdd
0.4
0.6
0.8
UNIT
V
Vpor_dcvdd_on
0.9
1.26
1.6
V
Vpor_avdd_on
0.5
0.7
0.9
V
Vpor_avdd_off
0.4
0.6
0.8
V
Table 2 Typical POR Operation (typical values, not tested)
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DEVICE DESCRIPTION
INTRODUCTION
The WM8750L is a low power audio codec offering a combination of high quality audio, advanced
features, low power and small size. These characteristics make it ideal for portable digital audio
applications such as MP3 and minidisk player / recorders. Stereo 24-bit multi-bit delta sigma ADCs
and DACs are used with oversampling digital interpolation and decimation filters.
The device includes three stereo analogue inputs that can be switched internally. Each can be used
as either a line level input or microphone input and LINPUT1/RINPUT1 and LINPUT2/RINPUT2 can
be configured as mono differential inputs. A programmable gain amplifier with automatic level control
(ALC) keeps the recording volume constant. The on-chip stereo ADC and DAC are of a high quality
using a multi-bit, low-order oversampling architecture to deliver optimum performance with low power
consumption.
The DAC output signal first enters an analogue mixer where an analogue input and/or the post-ALC
signal can be added to it. This mix is available on line and headphone outputs.
The WM8750L has a configurable digital audio interface where ADC data can be read and digital
audio playback data fed to the DAC. It supports a number of audio data formats including I2S, DSP
Mode (a burst mode in which frame sync plus 2 data packed words are transmitted), MSB-First, left
justified and MSB-First, right justified, and can operate in master or slave modes.
The WM8750L uses a unique clocking scheme that can generate many commonly used audio
sample rates from either a 12.00MHz USB clock or an industry standard 256/384 fs clock. This
feature eliminates the common requirement for an external phase-locked loop (PLL) in applications
where the master clock is not an integer multiple of the sample rate. Sample rates of 8kHz,
11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz, 48kHz, 88.2kHz and 96kHz can be
generated. The digital filters used for recording and playback are optimised for each sampling rate
used.
To allow full software control over all its features, the WM8750L offers a choice of 2 or 3 wire MPU
control interface. It is fully compatible and an ideal partner for a wide range of industry standard
microprocessors, controllers and DSPs.
The design of the WM8750L has given much attention to power consumption without compromising
performance. It operates at very low voltages, and includes the ability to power off parts of the
circuitry under software control, including standby and power off modes.
INPUT SIGNAL PATH
The input signal path for each channel consists of a switch to select between three analogue inputs,
followed by a PGA (programmable gain amplifier) and an optional microphone gain boost. A
differential input of either (LINPUT1 – RINPUT1) or (LINPUT2 – RINPUT2) may also be selected.
The gain of the PGA can be controlled either by the user or by the on-chip ALC function (see
Automatic Level Control).
The signal then enters an ADC where it is digitised. Alternatively, the two channels can also be
mixed in the analogue domain and digitised in one ADC while the other ADC is switched off. The
mono-mix signal appears on both digital output channels.
SIGNAL INPUTS
The WM8750L has three sets of high impedance, low capacitance AC coupled analogue inputs,
LINPUT1/RINPUT1, LINPUT2/RINPUT2 and LINPUT3/RINPUT3. Inputs can be configured as
microphone or line level by enabling or disabling the microphone gain boost.
LINSEL and RINSEL control bits (see Table 3) are used to select independently between external
inputs and internally generated differential products (LINPUT1-RINPUT1 or LINPUT2-RINPUT2). The
choice of differential signal, LINPUT1-RINPUT1 or LINPUT2-RINPUT2 is made using DS (refer to
Table 5).
As an example, the WM8750 can be set up to convert one differential and one single ended mono
signal by applying the differential signal to LINPUT1/RINPUT1 and the single ended signal to
RINPUT2. By setting LINSEL to L-R Differential (see Table 3), DS to LINPUT1 - RINPUT1 (see
Table 5) and RINSEL to RINPUT2, each mono signal can then be routed to a separate ADC or
Bypass path.
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The signal inputs are biased internally to the reference voltage VREF. Whenever the line inputs are
muted or the device placed into standby mode, the inputs are kept biased to VREF using special
anti-thump circuitry. This reduces any audible clicks that may otherwise be heard when changing
inputs.
DC MEASUREMENT
For DC measurements (for example, battery voltage monitoring), the input signal at the LINPUT1
and/or RINPUT1 pins can be taken directly into the respective ADC, bypassing both PGA and
microphone boost. The ADC output then becomes unsigned relative to AVDD, instead of being a
signed (two’s complement) number relative to VREF. Setting L/RDCM will override L/RINSEL. The
input range for dc measurement is AGND to AVDD.
REGISTER
ADDRESS
R32 (20h)
ADC Signal
Path Control
(Left)
R33 (21h)
ADC Signal
Path Control
(Right)
BIT
LABEL
DEFAULT
DESCRIPTION
7:6
LINSEL
00
Left Channel Input Select
00 = LINPUT1
01 = LINPUT2
10 = LINPUT3
11 = L-R Differential (either LINPUT1RINPUT1 or LINPUT2-RINPUT2,
selected by DS)
5:4
LMICBOOST
00
Left Channel Microphone Gain Boost
00 = Boost off (bypassed)
01 = 13dB boost
10 = 20dB boost
11 = 29dB boost
7:6
RINSEL
00
Right Channel Input Select
00 = RINPUT1
01 = RINPUT2
10 = RINPUT3
11 = L-R Differential (either LINPUT1RINPUT1 or LINPUT2-RINPUT2,
selected by DS)
5:4
RMICBOOST
00
Right Channel Microphone Gain Boost
00 = Boost off (bypassed)
01 = 13dB boost
10 = 20dB boost
11 = 29dB boost
Table 3 Input Software Control
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R31 (1Fh)
ADC input Mode
5
RDCM
0
Right Channel DC Measurement
0 = Normal Operation, PGA Enabled
1 = Measure DC level on RINPUT1
4
LDCM
0
Left Channel DC Measurement
0 = Normal Operation, PGA Enabled
1 = Measure DC level on LINPUT1
Table 4 DC Measurement Select
REGISTER
ADDRESS
BIT
R31 (1Fh)
ADC Input Mode
8
LABEL
DS
DEFAULT
0
DESCRIPTION
Differential input select
0: LINPUT1 - RINPUT1
1: LINPUT2 – RINPUT2
Table 5 Differential Input Select
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MONO MIXING
The stereo ADC can operate as a stereo or mono device, or the two channels can be mixed to mono,
either in the analogue domain (i.e. before the ADC) or in the digital domain (after the ADC).
MONOMIX selects the mode of operation. For analogue mono mix either the left or right channel
ADC can be used, allowing the unused ADC to be powered off or used for a dc measurement
conversion. The user also has the flexibility to select the data output from the audio interface using
DATSEL. The default is for left and right channel ADC data to be output, but the interface may also
be configured so that e.g. left channel ADC data is output as both left and right data for when an
analogue mono mix is selected.
Note:
If DC measurement is selected this overrides the MONOMIX selection.
REGISTER
ADDRESS
BIT
R31 (1Fh)
ADC input
Mode
7:6
LABEL
MONOMIX
[1:0]
DEFAULT
00
DESCRIPTION
00: Stereo
01: Analogue Mono Mix (using left ADC)
10: Analogue Mono Mix (using right ADC)
11: Digital Mono Mix
Table 6 Mono Mixing
REGISTER
ADDRESS
BIT
R23 (17h)
Additional
Control (1)
3:2
LABEL
DATSEL
[1:0]
DEFAULT
00
DESCRIPTION
00: left data=left ADC; right data =right ADC
01: left data =left ADC; right data = left ADC
10: left data = right ADC; right data =right
ADC
11: left data = right ADC; right data = left
ADC
Table 7 ADC Data Output Configuration
The MICBIAS output provides a low noise reference voltage suitable for biasing electret type
microphones and the associated external resistor biasing network. Refer to the Applications
Information section for recommended external components. The output can be enabled or disables
using the MICB control bit (see also the “Power Management” section).
REGISTER
ADDRESS
R25 (19h)
Power
Management (1)
BIT
1
LABEL
MICB
DEFAULT
0
DESCRIPTION
Microphone Bias Enable
0 = OFF (high impedance output)
1 = ON
Table 8 Microphone Bias Control
The internal MICBIAS circuitry is shown below. Note that the is a maximum source current capability
for MICBIAS is 3mA. The external biasing resistors therefore must be large enough to limit the
MICBIAS current to 3mA.
VMID
MICB
internal
resistor
MICBIAS
= 1.8 x VMID
= 0.9 X AVDD
internal
resistor
AGND
Figure 8 Microphone Bias Schematic
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PGA CONTROL
The PGA matches the input signal level to the ADC input range. The PGA gain is logarithmically
adjustable from +30dB to –17.25dB in 0.75dB steps. Each PGA can be controlled either by the user
or by the ALC function (see Automatic Level Control). When ALC is enabled for one or both
channels, then writing to the corresponding PGA control register has no effect.
The gain is independently adjustable on both Right and Left Line Inputs. Additionally, by controlling
the register bits LIVU and RIVU, the left and right gain settings can be simultaneously updated.
Setting the LZCEN and RZCEN bits enables a zero-cross detector which ensures that PGA gain
changes only occur when the signal is at zero, eliminating any zipper noise. If zero cross is enabled
a timeout is also available to update the gain if a zero cross does not occur. This function may be
enabled by setting TOEN in register R23 (17h).
The inputs can also be muted in the analogue domain under software control. The software control
registers are shown in Table 9. If zero crossing is enabled, it is necessary to enable zero cross
timeout to un-mute the input PGAs. This is because their outputs will not cross zero when muted.
Alternatively, zero cross can be disabled before sending the un-mute command.
REGISTER
ADDRESS
R0 (00h)
Left Channel
PGA
R1 (01h)
Right Channel
PGA
R23 (17h)
Additional
Control (1)
BIT
LABEL
DEFAULT
DESCRIPTION
8
LIVU
0
Left Volume Update
0 = Store LINVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LINVOL, right =
intermediate latch)
7
LINMUTE
1
Left Channel Input Analogue Mute
1 = Enable Mute
0 = Disable Mute
Note: LIVU must be set to un-mute.
6
LZCEN
0
Left Channel Zero Cross Detector
1 = Change gain on zero cross only
0 = Change gain immediately
5:0
LINVOL
[5:0]
010111
( 0dB )
Left Channel Input Volume Control
111111 = +30dB
111110 = +29.25dB
. . 0.75dB steps down to
000000 = -17.25dB
8
RIVU
0
Right Volume Update
0 = Store RINVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (right = RINVOL, left =
intermediate latch)
7
RINMUTE
1
Right Channel Input Analogue Mute
1 = Enable Mute
0 = Disable Mute
Note: RIVU must be set to un-mute.
6
RZCEN
0
Right Channel Zero Cross Detector
1 = Change gain on zero cross only
0 = Change gain immediately
5:0
RINVOL
[5:0]
010111
( 0dB )
Right Channel Input Volume Control
111111 = +30dB
111110 = +29.25dB
. . 0.75dB steps down to
000000 = -17.25dB
0
TOEN
0
Timeout Enable
0 : Timeout Disabled
1 : Timeout Enabled
Table 9 Input PGA Software Control
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ANALOGUE TO DIGITAL CONVERTER (ADC)
The WM8750L uses a multi-bit, oversampled sigma-delta ADC for each channel. The use of multi-bit
feedback and high oversampling rates reduces the effects of jitter and high frequency noise. The
ADC Full Scale input level is proportional to AVDD. With a 3.3V supply voltage, the full scale level is
1.0 Volts r.m.s. Any voltage greater than full scale may overload the ADC and cause distortion.
ADC DIGITAL FILTER
The ADC filters perform true 24 bit signal processing to convert the raw multi-bit oversampled data
from the ADC to the correct sampling frequency to be output on the digital audio interface. The digital
filter path is illustrated in Figure 9.
FROM ADC
DIGITAL
DECIMATOR
DIGITAL
FILTER
DIGITAL
HPF
TO DIGITAL
AUDIO
INTERFACE
ADCHPD
Figure 9 ADC Digital Filter
The ADC digital filters contain a digital high pass filter, selectable via software control. The high-pass
filter response is detailed in the Digital Filter Characteristics section. When the high-pass filter is
enabled the dc offset is continuously calculated and subtracted from the input signal. By setting
HPOR, the last calculated dc offset value is stored when the high-pass filter is disabled and will
continue to be subtracted from the input signal. If the DC offset is changed, the stored and
subtracted value will not change unless the high-pass filter is enabled. This feature can be used for
calibration purposes. In addition the highpass filter may be enabled separately on the left and right
channels (see Table 11).
The output data format can be programmed by the user to accommodate stereo or monophonic
recording on both inputs. The polarity of the output signal can also be changed under software
control. The software control is shown in Table 10.
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REGISTER
ADDRESS
R5 (05h)
ADC and DAC
Control
BIT
LABEL
DEFAULT
DESCRIPTION
6:5
ADCPOL
[1:0]
00
00 = Polarity not inverted
01 = L polarity invert
10 = R polarity invert
11 = L and R polarity invert
4
HPOR
0
Store dc offset when high-pass
filter disabled
1 = store offset
0 = clear offset
0
ADCHPD
0
ADC high-pass filter enable
(Digital)
HPFLREN = 0
1 = Disable high-pass filter on left
and right channels
0 = Enable high-pass filter on left
and right channels
HPFLREN = 1
0 = High-pass enabled on left,
disabled on right
1 = High-pass enabled on right,
disabled on left
R27 (1Bh)
5
HPFLREN
0
ADC high-pass filter left or right
enable
0 = High-pass filter enable/disable
on left and right channels
controlled by ADCHPD
1 = High-pass filter enabled on left
or right channel, as selected by
ADCHPD
Table 10 ADC Signal Path Control
HPFLREN
ADCHPD
0
0
High-pass filter enabled on left and right
channels
HIGH PASS MODE
0
1
High-pass filter disabled on left and right
channels
1
0
High-pass filter enabled on left channel,
disabled on right channel
1
1
High-pass filter disabled on left channel,
enabled on right channel
Table 11 ADC High Pass Filter Enable Modes
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DIGITAL ADC VOLUME CONTROL
The output of the ADCs can be digitally amplified or attenuated over a range from –97dB to +30dB in
0.5dB steps. The volume of each channel can be controlled separately. The gain for a given eight-bit
code X is given by:
0.5 × (X-195) dB for 1 ≤ X ≤ 255;
MUTE for X = 0
The LAVU and RAVU control bits control the loading of digital volume control data. When LAVU or
RAVU are set to 0, the LADCVOL or RADCVOL control data will be loaded into the respective control
register, but will not actually change the digital gain setting. Both left and right gain settings are
updated when either LAVU or RAVU are set to 1. This makes it possible to update the gain of both
channels simultaneously.
REGISTER
ADDRESS
R21 (15h)
Left ADC
Digital Volume
R22 (16h)
Right ADC
Digital Volume
BIT
LABEL
DEFAULT
DESCRIPTION
7:0
LADCVOL
[7:0]
11000011
( 0dB )
Left ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -97dB
0000 0010 = -96.5dB
... 0.5dB steps up to
1111 1111 = +30dB
8
LAVU
0
Left ADC Volume Update
0 = Store LADCVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LADCVOL, right =
intermediate latch)
7:0
RADCVOL
[7:0]
11000011
( 0dB )
Right ADC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -97dB
0000 0010 = -96.5dB
... 0.5dB steps up to
1111 1111 = +30dB
8
RAVU
0
Right ADC Volume Update
0 = Store RADCVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = intermediate latch, right
= RADCVOL)
Table 12 ADC Digital Volume Control
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AUTOMATIC LEVEL CONTROL (ALC)
The WM8750L has an automatic level control that aims to keep a constant recording volume
irrespective of the input signal level. This is achieved by continuously adjusting the PGA gain so that
the signal level at the ADC input remains constant. A digital peak detector monitors the ADC output
and changes the PGA gain if necessary. Note that when the ALC function is enabled, the settings of
registers 0 and 1 (LINVOL, LIVU, LIZC, LINMUTE, RINVOL, RIVU, RIZC and RINMUTE) are
ignored.
input
signal
PGA
gain
signal
after
ALC
ALC
target
level
hold
time
decay
time
attack
time
Figure 10 ALC Operation
The ALC function is enabled using the ALCSEL control bits. When enabled, the recording volume
can be programmed between –6dB and –28.5dB (relative to ADC full scale) using the ALCL register
bits. An upper limit for the PGA gain can be imposed by setting the MAXGAIN control bits.
HLD, DCY and ATK control the hold, decay and attack times, respectively:
Hold time is the time delay between the peak level detected being below target and the PGA gain
beginning to ramp up. It can be programmed in power-of-two (2n) steps, e.g. 2.67ms, 5.33ms,
10.67ms etc. up to 43.7s. Alternatively, the hold time can also be set to zero. The hold time only
applies to gain ramp-up, there is no delay before ramping the gain down when the signal level is
above target.
Decay (Gain Ramp-Up) Time is the time that it takes for the PGA gain to ramp up across 90% of its
range (e.g. from –15B up to 27.75dB). The time it takes for the recording level to return to its target
value therefore depends on both the decay time and on the gain adjustment required. If the gain
adjustment is small, it will be shorter than the decay time. The decay time can be programmed in
power-of-two (2n) steps, from 24ms, 48ms, 96ms, etc. to 24.58s.
Attack (Gain Ramp-Down) Time is the time that it takes for the PGA gain to ramp down across 90%
of its range (e.g. from 27.75dB down to -15B gain). The time it takes for the recording level to return
to its target value therefore depends on both the attack time and on the gain adjustment required. If
the gain adjustment is small, it will be shorter than the attack time. The attack time can be
programmed in power-of-two (2n) steps, from 6ms, 12ms, 24ms, etc. to 6.14s.
When operating in stereo, the peak detector takes the maximum of left and right channel peak
values, and any new gain setting is applied to both left and right PGAs, so that the stereo image is
preserved. However, the ALC function can also be enabled on one channel only. In this case, only
one PGA is controlled by the ALC mechanism, while the other channel runs independently with its
PGA gain set through the control register.
When one ADC channel is unused or used for DC measurement, the peak detector disregards that
channel. The ALC function can also operate when the two ADC outputs are mixed to mono in the
digital domain, but not if they are mixed to mono in the analogue domain, before entering the ADCs.
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REGISTER
ADDRESS
R17 (11h)
ALC Control 1
R18 (12h)
ALC Control 2
R19 (13h)
ALC Control 3
BIT
LABEL
DEFAULT
DESCRIPTION
8:7
ALCSEL
[1:0]
00
(OFF)
ALC function select
00 = ALC off (PGA gain set by register)
01 = Right channel only
10 = Left channel only
11 = Stereo (PGA registers unused)
Note: ensure that LINVOL and
RINVOL settings (reg. 0 and 1) are
the same before entering this mode.
6:4
MAXGAIN
[2:0]
111
(+30dB)
Set Maximum Gain of PGA
111 : +30dB
110 : +24dB
….(-6dB steps)
001 : -6dB
000 : -12dB
3:0
ALCL
[3:0]
1011
(-12dB)
ALC target – sets signal level at ADC
input
0000 = -28.5dB FS
0001 = -27.0dB FS
… (1.5dB steps)
1110 = -7.5dB FS
1111 = -6dB FS
7
ALCZC
0 (zero
cross
off)
ALC uses zero cross detection circuit.
3:0
HLD
[3:0]
0000
(0ms)
ALC hold time before gain is increased.
0000 = 0ms
0001 = 2.67ms
0010 = 5.33ms
… (time doubles with every step)
1111 = 43.691s
7:4
DCY
[3:0]
0011
(192ms)
ALC decay (gain ramp-up) time
0000 = 24ms
0001 = 48ms
0010 = 96ms
… (time doubles with every step)
1010 or higher = 24.58s
3:0
ATK
[3:0]
0010
(24ms)
ALC attack (gain ramp-down) time
0000 = 6ms
0001 = 12ms
0010 = 24ms
… (time doubles with every step)
1010 or higher = 6.14s
Table 13 ALC Control
PEAK LIMITER
To prevent clipping when a large signal occurs just after a period of quiet, the ALC circuit includes a
limiter function. If the ADC input signal exceeds 87.5% of full scale (–1.16dB), the PGA gain is
ramped down at the maximum attack rate (as when ATK = 0000), until the signal level falls below
87.5% of full scale. This function is automatically enabled whenever the ALC is enabled.
Note:
If ATK = 0000, then the limiter makes no difference to the operation of the ALC. It is designed to
prevent clipping when long attack times are used.
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NOISE GATE
When the signal is very quiet and consists mainly of noise, the ALC function may cause “noise
pumping”, i.e. loud hissing noise during silence periods. The WM8750L has a noise gate function
that prevents noise pumping by comparing the signal level at the LINPUT1/2/3 and/or RINPUT1/2/3
pins against a noise gate threshold, NGTH. The noise gate cuts in when:
•
Signal level at ADC [dB] < NGTH [dB] + PGA gain [dB] + Mic Boost gain [dB]
This is equivalent to:
•
Signal level at input pin [dB] < NGTH [dB]
The ADC output can then either be muted or alternatively, the PGA gain can be held constant
(preventing it from ramping up as it normally would when the signal is quiet).
The table below summarises the noise gate control register. The NGTH control bits set the noise
gate threshold with respect to the ADC full-scale range. The threshold is adjusted in 1.5dB steps.
Levels at the extremes of the range may cause inappropriate operation, so care should be taken with
set–up of the function. Note that the noise gate only works in conjunction with the ALC function, and
always operates on the same channel(s) as the ALC (left, right, both, or none).
REGISTER
ADDRESS
R20 (14h)
Noise Gate
Control
BIT
LABEL
DEFAULT
DESCRIPTION
7:3
NGTH
[4:0]
00000
Noise gate threshold
00000 -76.5dBfs
00001 -75dBfs
… 1.5 dB steps
11110 -31.5dBfs
11111 -30dBfs
2:1
NGG
[1:0]
00
Noise gate type
X0 = PGA gain held constant
01 = mute ADC output
11 = reserved (do not use this setting)
0
NGAT
0
Noise gate function enable
1 = enable
0 = disable
Table 14 Noise Gate Control
Note:
The performance of the ADC may degrade at high input signal levels if the monitor bypass mux is
selected with MIC boost and ALC enabled.
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3D STEREO ENHANCEMENT
The WM8750L has a digital 3D enhancement option to artificially increase the separation between
the left and right channels. This effect can be used for recording or playback, but not for both
simultaneously. Selection of 3D for record or playback is controlled by register bit MODE3D.
Important:
Switching the 3D filter from record to playback or from playback to record may only be done
when ADC and DAC are disabled. The WM8750L control interface will only allow MODE3D to
be changed when ADC and DAC are disabled (i.e. bits ADCL, ADCR, DACL and DACR in reg.
26 / 1Ah are all zero).
The 3D enhancement function is activated by the 3DEN bit, and has two programmable parameters.
The 3DDEPTH setting controls the degree of stereo expansion. Additionally, one of four filter
characteristics can be selected for the 3D processing, using the 3DVC and 3DLC control bits.
REGISTER
ADDRESS
R16 (10h)
3D enhance
BIT
LABEL
DEFAULT
DESCRIPTION
7
MODE3D
0
Playback/Record 3D select
0 = 3D selected for Record
1 = 3D selected for Playback
6
3DUC
0
Upper Cut-off frequency
0 = High (2.2kHz at 48kHz
sampling)
1 = Low (1.5kHz at 48kHz sampling)
5
3DLC
0
Lower Cut-off frequency
0 = Low (200Hz at 48kHz sampling)
1 = High (500Hz at 48kHz sampling)
4:1
3DDEPTH
[3:0]
0000
Stereo depth
0000: 0% (minimum 3D effect)
0001: 6.67%
....
1110: 93.3%
1111: 100% (maximum 3D effect)
0
3DEN
0
3D function enable
1: enabled
0: disabled
Table 15 3D Stereo Enhancement Function
When 3D enhancement is enabled (and/or the graphic equaliser for playback) it may be necessary to
attenuate the signal by 6dB to avoid limiting. This is a user selectable function, enabled by setting
ADCDIV2 for the record path and DACDIV2 for the playback path.
REGISTER
ADDRESS
R5 (05h)
ADC and DAC
control
BIT
LABEL
DEFAULT
DESCRIPTION
8
ADCDIV2
0
ADC 6dB attenuate enable
0 = disabled (0dB)
1 = -6dB enabled
7
DACDIV2
0
DAC 6dB attenuate enable
0 = disabled (0dB)
1 = -6dB enabled
Table 16 ADC and DAC 6dB Attenuation Select
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OUTPUT SIGNAL PATH
The WM8750L output signal paths consist of digital filters, DACs, analogue mixers and output
drivers. The digital filters and DACs are enabled when the WM8750L is in ‘playback only’ or ‘record
and playback’ mode. The mixers and output drivers can be separately enabled by individual control
bits (see Analogue Outputs). Thus it is possible to utilise the analogue mixing and amplification
provided by the WM8750L, irrespective of whether the DACs are running or not.
The WM8750L receives digital input data on the DACDAT pin. The digital filter block processes the
data to provide the following functions:
•
•
•
Digital volume control
Graphic equaliser and Dynamic Bass Boost
Sigma-Delta Modulation
Two high performance sigma-delta audio DACs convert the digital data into two analogue signals (left
and right). These can then be mixed with analogue signals from the LINPUT1/2/3 and RINPUT1/2/3
pins, and the mix is fed to the output drivers, LOUT1/ROUT1, LOUT2/ROUT2, OUT3 and
MONOOUT.
•
LOUT1/ROUT1/OUT3: can drive a 16Ω or 32Ω stereo headphone or stereo line output.
•
LOUT2/ROUT2: can drive a 16Ω or 32Ω stereo headphone or stereo line output, or an
8Ω mono speaker.
MONOOUT: can drive a mono line output or other load down to 10kΩ
•
DIGITAL DAC VOLUME CONTROL
The signal volume from each DAC can be controlled digitally, in the same way as the ADC volume
(see Digital ADC Volume Control). The gain and attenuation range is –127dB to 0dB in 0.5dB steps.
The level of attenuation for an eight-bit code X is given by:
0.5 × (X-255) dB for 1 ≤ X ≤ 255;
MUTE for X = 0
The LDVU and RDVU control bits control the loading of digital volume control data. When LDVU or
RDVU are set to 0, the LDACVOL or RDACVOL control data is loaded into an intermediate register,
but the actual gain does not change. Both left and right gain settings are updated simultaneously
when either LDVU or RDVU are set to 1.
REGISTER
ADDRESS
R10 (0Ah)
Left Channel
Digital Volume
R11 (0Bh)
Right Channel
Digital Volume
BIT
LABEL
DEFAULT
DESCRIPTION
8
LDVU
0
Left DAC Volume Update
0 = Store LDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LDACVOL, right =
intermediate latch)
7:0
LDACVOL
[7:0]
11111111
( 0dB )
Left DAC Digital Volume Control
0000 0000 = Digital Mute
0000 0001 = -127dB
0000 0010 = -126.5dB
... 0.5dB steps up to
1111 1111 = 0dB
8
RDVU
0
Right DAC Volume Update
0 = Store RDACVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = intermediate latch, right
= RDACVOL)
7:0
RDACVOL
[7:0]
11111111
( 0dB )
Right DAC Digital Volume Control
similar to LDACVOL
Table 17 Digital Volume Control
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GRAPHIC EQUALISER
The WM8750L has a digital graphic equaliser and adaptive bass boost function. This function
operates on digital audio data before it is passed to the audio DACs. Bass enhancement can take
two different forms:
•
Linear bass control: bass signals are amplified or attenuated by a user programmable
gain. This is independent of signal volume, and very high bass gains on loud signals
may lead to signal clipping.
•
Adaptive bass boost: The bass volume is amplified by a variable gain. When the bass
volume is low, it is boosted more than when the bass volume is high. This method is
recommended because it prevents clipping, and usually sounds more pleasant to the
human ear.
Treble control applies a user programmable gain, without any adaptive boost function. Bass and
treble control are completely independent with separately programmable gains and filter
characteristics.
REGISTER
ADDRESS
R12 (0Ch)
Bass Control
R13 (0Dh)
Treble Control
BIT
LABEL
DEFAULT
DESCRIPTION
7
BB
0
Bass Boost
0 = Linear bass control
1 = Adaptive bass boost
6
BC
0
Bass Filter Characteristic
0 = Low Cutoff (130Hz at 48kHz sampling)
1 = High Cutoff (200Hz at 48kHz sampling)
3:0
BASS
[3:0]
1111
(Disabled)
Bass Intensity
Code
BB=0
BB=1
0000
+9dB
15 (max)
0001
+9dB
14
0010
+7.5dB
13
0011
+6dB
12
0100
+4.5dB
11
0101
+3dB
10
0110
+1.5dB
9
0111
0dB
8
1000
-1.5dB
7
1001
-3dB
6
1010
-4.5dB
5
1011
-6dB
4
1100
-6dB
3
1101
-6dB
2
1110
-6dB
1
1111
Bypass (OFF)
6
TC
0
Treble Filter Characteristic
0 = High Cutoff (8kHz at 48kHz sampling)
1 = Low Cutoff (4kHz at 48kHz sampling)
3:0
TRBL
[3:0]
1111
(Disabled)
Treble Intensity
0000 or 0001 = +9dB
0010 = +7.5dB
… (1.5dB steps)
1011 to 1110 = -6dB
1111 = Disable
Table 18 Graphic Equaliser
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DIGITAL TO ANALOGUE CONVERTER (DAC)
After passing through the graphic equaliser filters, digital ‘de-emphasis’ can be applied to the audio
data if necessary (e.g. when the data comes from a CD with pre-emphasis used in the recording).
De-emphasis filtering is available for sample rates of 48kHz, 44.1kHz and 32kHz.
The WM8750L also has a Soft Mute function, which gradually attenuates the volume of the digital
signal to zero. When removed, the gain will return to the original setting. This function is enabled by
default. To play back an audio signal, it must first be disabled by setting the DACMU bit to zero.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R5 (05h)
ADC and DAC
Control
2:1
DEEMP
[1:0]
00
De-emphasis Control
11 = 48kHz sample rate
10 = 44.1kHz sample rate
01 = 32kHz sample rate
00 = No De-emphasis
3
DACMU
1
Digital Soft Mute
1 = mute
0 = no mute (signal active)
Table 19 DAC Control
The digital audio data is converted to oversampled bit streams in the on-chip, true 24-bit digital
interpolation filters. The bitstream data enters two multi-bit, sigma-delta DACs, which convert them to
high quality analogue audio signals. The multi-bit DAC architecture reduces high frequency noise and
sensitivity to clock jitter. It also uses a Dynamic Element Matching technique for high linearity and
low distortion.
In normal operation, the left and right channel digital audio data is converted to analogue in two
separate DACs. However, it is also possible to disable one channel, so that the same signal (left or
right) appears on both analogue output channels. Additionally, there is a mono-mix mode where the
two audio channels are mixed together digitally and then converted to analogue using only one DAC,
while the other DAC is switched off. The mono-mix signal can be selected to appear on both
analogue output channels.
The DAC output defaults to non-inverted. Setting DACINV will invert the DAC output phase on both
left and right channels.
REGISTER
ADDRESS
R23 (17h)
Additional
Control (1)
BIT
LABEL
5:4
DMONOMIX
[1:0]
00
DAC mono mix
00: stereo
01: mono ((L+R)/2) into DACL, ‘0’ into
DACR
10: mono ((L+R)/2) into DACR, ‘0’ into
DACL
11: mono ((L+R)/2) into DACL and
DACR
DACINV
0
DAC phase invert
0 : non-inverted
1 : inverted
1
DEFAULT
DESCRIPTION
Table 20 DAC Mono Mix and Phase Invert Select
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OUTPUT MIXERS
The WM8750L provides the option to mix the DAC output signal with analogue line-in signals from
the LINPUT1/2/3, RINPUT1/2/3 pins or a mono differential input (LINPUT1 – RINPUT1) or (LINPUT2
– RINPUT2), selected by DS (see Table 5) . The level of the mixed-in signals can be controlled with
PGAs (Programmable Gain Amplifiers).
The mono mixer is designed to allow a number of signal combinations to be mixed, including the
possibility of mixing both the right and left channels together to produce a mono output. To prevent
overloading of the mixer when full-scale DAC left and right signals are input, the mixer inputs from
the DAC outputs each have a fixed gain of -6dB. The bypass path inputs to the mono mixer have
variable gain as determined by R38/R39 bits [6:4].
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R34 (22h)
Left Mixer (1)
2:0
LMIXSEL
000
Left Input Selection for Output Mix
000 = LINPUT1
001 = LINPUT2
010 = LINPUT3
011 = Left ADC Input (after PGA /
MICBOOST)
100 = Differential input
R36 (24h)
Right Mixer
(1)
2:0
RMIXSEL
000
Right Input Selection for Output Mix
000 = RINPUT1
001 = RINPUT2
010 = RINPUT3
011 = Right ADC Input (after PGA /
MICBOOST)
100 = Differential input
Table 21 Output Mixer Signal Selection
REGISTER
ADDRESS
R34 (22h)
Left Mixer
Control (1)
R35 (23h)
Left Mixer
Control (2)
BIT
LABEL
DEFAULT
DESCRIPTION
8
LD2LO
0
Left DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
7
LI2LO
0
LMIXSEL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
LI2LOVOL
[2:0]
101
(-9dB)
LMIXSEL Signal to Left Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
8
RD2LO
0
Right DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
7
RI2LO
0
RMIXSEL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
RI2LOVOL
[2:0]
101
(-9dB)
RMIXSEL Signal to Left Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
Table 22 Left Output Mixer Control
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REGISTER
ADDRESS
R36 (24h)
Right Mixer
Control (1)
R37 (25h)
Right Mixer
Control (2)
BIT
LABEL
DEFAULT
DESCRIPTION
8
LD2RO
0
Left DAC to Right Mixer
0 = Disable (Mute)
1 = Enable Path
7
LI2RO
0
LMIXSEL Signal to Right Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
LI2ROVOL
[2:0]
101
(-9dB)
LMIXSEL Signal to Right Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
8
RD2RO
0
Right DAC to Right Mixer
0 = Disable (Mute)
1 = Enable Path
7
RI2RO
0
RMIXSEL Signal to Right Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
RI2ROVOL
[2:0]
101
(-9dB)
RMIXSEL Signal to Right Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
Table 23 Right Output Mixer Control
REGISTER
ADDRESS
R38 (26h)
Mono Mixer
Control (1)
R39 (27h)
Mono Mixer
Control (2)
BIT
LABEL
DEFAULT
DESCRIPTION
8
LD2MO
0
Left DAC to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
7
LI2MO
0
LMIXSEL Signal to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
LI2MOVOL
[2:0]
101
(-9dB)
LMIXSEL Signal to Mono Mixer
Volume
000 = +6dB
… (3dB steps)
111 = -15dB
8
RD2MO
0
Right DAC to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
7
RI2MO
0
RMIXSEL Signal to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
RI2MOVOL
[2:0]
101
(-9dB)
RMIXSEL Signal to Mono Mixer
Volume
000 = +6dB
… (3dB steps)
111 = -15dB
Table 24 Mono Output Mixer Control
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ANALOGUE OUTPUTS
LOUT1/ROUT1 OUTPUTS
The LOUT1 and ROUT1 pins can drive a 16Ω or 32Ω headphone or a line output (see Headphone
Output and Line Output sections, respectively). The signal volume on LOUT1 and ROUT1 can be
independently adjusted under software control by writing to LOUT1VOL and ROUT1VOL,
respectively. Note that gains over 0dB may cause clipping if the signal is large. Any gain setting
below 0101111 (minimum) mutes the output driver. The corresponding output pin remains at the
same DC level (the reference voltage on the VREF pin), so that no click noise is produced when
muting or un-muting.
A zero cross detect on the analogue output may also be enabled when changing the gain setting to
minimize audible clicks and zipper noise as the gain updates. If zero cross is enabled a timeout is
also available to update the gain if a zero cross does not occur. This function may be enabled by
setting TOEN in register R23 (17h).
REGISTER
ADDRESS
R2 (02h)
LOUT1
Volume
R3 (03h)
ROUT1
Volume
BIT
LABEL
DEFAULT
DESCRIPTION
8
LO1VU
0
Left Volume Update
0 = Store LOUT1VOL in intermediate
latch (no gain change)
1 = Update left and right channel gains
(left = LOUT1VOL, right =
intermediate latch)
7
LO1ZC
0
Left zero cross enable
1 = Change gain on zero cross only
0 = Change gain immediately
6:0
LOUT1VOL
[6:0]
1111001
(0dB)
LOUT1 Volume
1111111 = +6dB
… (80 steps)
0110000 = -67dB
0101111 to 0000000 = Analogue
MUTE
8
RO1VU
0
Right Volume Update
0 = Store ROUT1VOL in intermediate
latch (no gain change)
1 = Update left and right channel gains
(left = intermediate latch, right =
ROUT1VOL)
7
RO1ZC
0
Right zero cross enable
1 = Change gain on zero cross only
0 = Change gain immediately
6:0
ROUT1VOL
[6:0]
1111001
ROUT1 Volume
Similar to LOUT1VOL
Table 25 LOUT1/ROUT1 Volume Control
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LOUT2/ROUT2 OUTPUTS
The LOUT2 and ROUT2 output pins are essentially similar to LOUT1 and ROUT1, but they are
independently controlled and can also drive an 8Ω mono speaker (see Speaker Output section). For
speaker drive, the ROUT2 signal must be inverted (ROUT2INV = 1), so that the left and right channel
are mixed to mono in the speaker [L–(-R) = L+R].
REGISTER
ADDRESS
R40 (28h)
LOUT2
Volume
R41 (29h)
ROUT2
Volume
R24 (18h)
Additional
Control (2)
BIT
LABEL
DEFAULT
DESCRIPTION
6:0
LOUT2VOL
[6:0]
1111001
(0dB)
Similar to LOUT1VOL
7
LO2ZC
0
Left zero cross enable
1 = Change gain on zero cross only
0 = Change gain immediately
8
LO2VU
0
Same as LO1VU
6:0
ROUT2VOL
[6:0]
1111001
(0dB)
Similar ROUT1VOL
7
RO2ZC
0
Right zero cross enable
1 = Change gain on zero cross only
0 = Change gain immediately
8
RO2VU
0
Same as RO1VU
4
ROUT2INV
0
ROUT2 Invert
0 = No Inversion (0° phase shift)
1 = Signal inverted (180° phase shift)
Table 26 LOUT2/ROUT2 Volume Control
MONO OUTPUT
The MONOOUT pin can drive a mono line output. The signal volume on MONOOUT can be adjusted
under software control by writing to MONOOUTVOL.
REGISTER
ADDRESS
R42 (2Ah)
MONOOUT
Volume
BIT
LABEL
DEFAULT
DESCRIPTION
6:0
MONOOUT
VOL [6:0]
1111001
(0dB)
MONOOUT Volume
1111111 = +6dB
… (80 steps)
0110000 = -67dB
0101111 to 0000000 = Analogue MUTE
7
MOZC
0
MONOOUT zero cross enable
1 = Change gain on zero cross only
0 = Change gain immediately
Table 27 MONOOUT Volume Control
OUT3 OUTPUT
The OUT3 pin can drive a 16Ω or 32Ω headphone or a line output or be used as a DC reference for a
headphone output (see Headphone Output section). It can be selected to either drive out an inverted
ROUT1 or inverted MONOOUT for e.g. an earpiece drive between OUT3 and LOUT1 or differential
output between OUT3 and MONOOUT. OUT3 can also drive an un-inverted ROUT1 signal, which
originates at the right mixer output before the output PGA.
OUT3SW selects the mode of operation required.
REGISTER
ADDRESS
R24 (18h)
Additional
Control (2)
BIT
8:7
LABEL
OUT3SW
[1:0]
DEFAULT
00
DESCRIPTION
OUT3 select
00 : VREF
01 : ROUT1 signal (volume controlled by
ROUT1VOL)
10 : MONOOUT
11 : right mixer output (no volume
control through ROUT1VOL)
Table 28 OUT3 Select
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ENABLING THE OUTPUTS
Each analogue output of the WM8750L can be separately enabled or disabled. The analogue mixer
associated with each output is powered on or off along with the output pin. All outputs are disabled by
default. To save power, unused outputs should remain disabled.
Outputs can be enabled at any time, except when VREF is disabled (VR=0), as this may cause pop
noise (see “Power Management” and “Applications Information” sections)
REGISTER
ADDRESS
R26 (1Ah)
Power
Management
(2)
BIT
LABEL
DEFAULT
DESCRIPTION
6
LOUT1
0
LOUT1 Enable
5
ROUT1
0
ROUT1 Enable
4
LOUT2
0
LOUT2 Enable
3
ROUT2
0
ROUT2 Enable
2
MONO
0
MONOOUT Enable
1
OUT3
0
OUT3 Enable
Note: All “Enable” bits are 1 = ON, 0 = OFF
Table 29 Analogue Output Control
Whenever an analogue output is disabled, it remains connected to VREF (pin 20) through a resistor.
This helps to prevent pop noise when the output is re-enabled. The resistance between VREF and
each output can be controlled using the VROI bit in register 27. The default is low (1.5kΩ), so that
any capacitors on the outputs can charge up quickly at start-up. If a high impedance is desired for
disabled outputs, VROI can then be set to 1, increasing the resistance to about 40kΩ.
REGISTER
ADDRESS
R27 (1Bh)
Additional (1)
BIT
6
LABEL
VROI
DEFAULT
0
DESCRIPTION
VREF to analogue output resistance
0: 1.5 kΩ
1: 40 kΩ
Table 30 Disabled Outputs to VREF Resistance
HEADPHONE SWITCH
The RINPUT3/HPDETECT pin can be used as a headphone switch control input to automatically
disable the speaker output and enable the headphone output e.g. when a headphone is plugged into
a jack socket. In this mode, enabled by setting HPSWEN, HPDETECT switches between headphone
and speaker outputs (e.g. when the pin is connected to a mechanical switch in the headphone socket
to detect plug-in). The HPSWPOL bit reverses the pin’s polarity. Note that the LOUT1, ROUT1,
LOUT2 and ROUT2 bits in register 26 must also be set for headphone and speaker output (see
Table 31 and Table 32).
Note:
When RINPUT3/HPDETECT is used as the HPDETECT input, the thresholds become CMOS levels
(0.3 AVDD / 0.7 AVDD).
HPSWEN
HPSWPOL HPDETECT
L/ROUT1
L/ROUT2
Headphone
Speaker
(PIN23)
(reg. 26)
(reg. 26)
enabled
enabled
0
X
X
0
0
no
no
0
X
X
0
1
no
yes
0
X
X
1
0
yes
no
0
X
X
1
1
yes
yes
1
0
0
X
0
no
no
1
0
0
X
1
no
yes
1
0
1
0
X
no
no
1
0
1
1
X
yes
no
1
1
0
0
X
no
no
1
1
0
1
X
yes
no
1
1
1
X
0
no
no
1
1
1
X
1
no
yes
Table 31 Headphone Switch Operation
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REGISTER
ADDRESS
R24 (18h)
Additional
Control (2)
BIT
LABEL
DEFAULT
DESCRIPTION
6
HPSWEN
0
Headphone Switch Enable
0 : Headphone switch disabled
1 : Headphone switch enabled
5
HPSWPOL
0
Headphone Switch Polarity
0 : HPDETECT high = headphone
1 : HPDETECT high = speaker
Table 32 Headphone Switch
Figure 11 Example Headset Detection Circuit Using Normally-Open Switch
Figure 12 Example Headset Detection Circuit Using Normally-Closed Switch
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THERMAL SHUTDOWN
The speaker and headphone outputs can drive very large currents. To protect the WM8750L from
overheating a thermal shutdown circuit is included. If the device temperature reaches approximately
1500C and the thermal shutdown circuit is enabled (TSDEN = 1 ) then the speaker and headphone
amplifiers (outputs OUT1L/R, OUT2L/R and OUT3) will be disabled.
REGISTER
ADDRESS
BIT
R23 (17h)
Additional
Control (1)
8
LABEL
TSDEN
DEFAULT
0
DESCRIPTION
Thermal Shutdown Enable
0 : thermal shutdown disabled
1 : thermal shutdown enabled
Table 33 Thermal Shutdown
HEADPHONE OUTPUT
Analogue outputs LOUT1/ROUT1, LOUT2/ROUT2, and OUT3, can drive a 16Ω or 32Ω headphone
load, either through DC blocking capacitors, or DC coupled without any capacitor.
DC Coupled Headphone Output
(OUT3SW = 00)
Headphone Output using DC blocking
capacitors
LOUT1/2
C1 220uF
LOUT1/2
ROUT1/2
WM8750L
WM8750L
C2 220uF
ROUT1/2
HPGND = 0V
OUT3 = VREF
Figure 13 Recommended Headphone Output Configurations
When DC blocking capacitors are used, then their capacitance and the load resistance together
determine the lower cut-off frequency, fc. Increasing the capacitance lowers fc, improving the bass
response. Smaller capacitance values will diminish the bass response. Assuming a 16 Ohm load and
C1, C2 = 220µF:
fc = 1 / 2π RLC1 = 1 / (2π x 16Ω x 220µF) = 45 Hz
In the DC coupled configuration, the headphone “ground” is connected to the OUT3 pin, which must
be enabled by setting OUT3 = 1 and OUT3SW = 00. As the OUT3 pin produces a DC voltage of
AVDD/2 (=VREF), there is no DC offset between LOUT1/ROUT1 and OUT3, and therefore no DC
blocking capacitors are required. This saves space and material cost in portable applications.
It is recommended to connect the DC coupled headphone outputs only to headphones, and not to
the line input of another device. Although the built-in short circuit protection will prevent any damage
to the headphone outputs, such a connection may be noisy, and may not function properly if the
other device is grounded.
SPEAKER OUTPUT
LOUT2 and ROUT2 can differentially drive a mono 8Ω speaker as shown below.
LEFT
MIXER
LOUT2
WM8750L
LOUT2VOL
ROUT2INV = 1
VSPKR = L-(-R) = L+R
-1
RIGHT
MIXER
ROUT2VOL
ROUT2
Figure 14 Speaker Output Connection
The right channel is inverted by setting the ROUT2INV bit, so that the signal across the loudspeaker
is the sum of left and right channels.
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LINE OUTPUT
The analogue outputs, LOUT1/ROUT1 and LOUT2/ROUT2, can be used as line outputs.
Additionally, OUT3 and MONOOUT can be used as a stereo line-out by setting OUT3SW=11 (reg.
24) and ensuring the contents of registers 38 and 39 (mono-out mix) are the same as reg. 34 and 35
(left out mix). Recommended external components are shown below.
C1
1uF
R1
100 Ohm
LOUT1/2
or OUT3 (OUT3SW=11)
AGND
WM8750L
ROUT1/2
or MONOOUT
C2
1uF
R2
100 Ohm
AGND
LINE-OUT
SOCKET
(LEFT)
LINE-OUT
SOCKET
(RIGHT)
Figure 15 Recommended Circuit for Line Output
The DC blocking capacitors and the load resistance together determine the lower cut-off frequency,
fc. Assuming a 10 kOhm load and C1, C2 = 1µF:
fc = 1 / 2π (RL+R1) C1 = 1 / (2π x 10.1kΩ x 1µF) = 16 Hz
Increasing the capacitance lowers fc, improving the bass response. Smaller values of C1 and C2 will
diminish the bass response. The function of R1 and R2 is to protect the line outputs from damage
when used improperly.
DIGITAL AUDIO INTERFACE
The digital audio interface is used for inputting DAC data into the WM8750L and outputting ADC data
from it. It uses five pins:
•
•
•
ADCDAT: ADC data output
ADCLRC: ADC data alignment clock
DACDAT: DAC data input
•
DACLRC: DAC data alignment clock
•
BCLK: Bit clock, for synchronisation
The clock signals BCLK, ADCLRC and DACLRC can be outputs when the WM8750L operates as a
master, or inputs when it is a slave (see Master and Slave Mode Operation, below).
Four different audio data formats are supported:
•
•
Left justified
Right justified
2
•
IS
•
DSP mode
All four of these modes are MSB first. They are described in Audio Data Formats, below. Refer to the
Electrical Characteristic section for timing information.
MASTER AND SLAVE MODE OPERATION
The WM8750L can be configured as either a master or slave mode device. As a master device the
WM8750L generates BCLK, ADCLRC and DACLRC and thus controls sequencing of the data
transfer on ADCDAT and DACDAT. In slave mode, the WM8750L responds with data to clocks it
receives over the digital audio interface. The mode can be selected by writing to the MS bit (see
Table 23). Master and slave modes are illustrated below.
BCLK
BCLK
ADCLRC
WM8750
CODEC
DACLRC
ADCDAT
DSP
ENCODER/
DECODER
DACDAT
Note: The ADC and DAC can run at different sample rates
Figure 16 Master Mode
w
ADCLRC
WM8750
CODEC
DSP
ENCODER/
DECODER
DACLRC
ADCDAT
DACDAT
Note: The ADC and DAC can run at different sample rates
Figure 17 Slave Mode
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AUDIO DATA FORMATS
In Left Justified mode, the MSB is available on the first rising edge of BCLK following a LRCLK
transition. The other bits up to the LSB are then transmitted in order. Depending on word length,
BCLK frequency and sample rate, there may be unused BCLK cycles before each LRCLK transition.
Figure 18 Left Justified Audio Interface (assuming n-bit word length)
In Right Justified mode, the LSB is available on the last rising edge of BCLK before a LRCLK
transition. All other bits are transmitted before (MSB first). Depending on word length, BCLK
frequency and sample rate, there may be unused BCLK cycles after each LRCLK transition.
Figure 19 Right Justified Audio Interface (assuming n-bit word length)
2
In I S mode, the MSB is available on the second rising edge of BCLK following a LRCLK transition.
The other bits up to the LSB are then transmitted in order. Depending on word length, BCLK
frequency and sample rate, there may be unused BCLK cycles between the LSB of one sample and
the MSB of the next.
Figure 20 I2S Justified Audio Interface (assuming n-bit word length)
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st
In DSP/PCM mode, the left channel MSB is available on either the 1 (mode B) or 2nd (mode A)
rising edge of BCLK (selectable by LRP) following a rising edge of LRC. Right channel data
immediately follows left channel data. Depending on word length, BCLK frequency and sample rate,
there may be unused BCLK cycles between the LSB of the right channel data and the next sample.
In device master mode, the LRC output will resemble the frame pulse shown in Figure 21 and Figure
22. In device slave mode, Figure 23 and Figure 24, it is possible to use any length of frame pulse
less than 1/fs, providing the falling edge of the frame pulse occurs greater than one BCLK period
before the rising edge of the next frame pulse.
Figure 21 DSP/PCM Mode Audio Interface (mode A, LRP=0, Master)
Figure 22 DSP/PCM Mode Audio Interface (mode B, LRP=1, Master)
Figure 23 DSP/PCM Mode Audio Interface (mode A, LRP=0, Slave)
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Figure 24 DSP/PCM Mode Audio Interface (mode B, LRP=0, Slave)
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AUDIO INTERFACE CONTROL
The register bits controlling audio format, word length and master / slave mode are summarised in
Table 34. MS selects audio interface operation in master or slave mode. In Master mode BCLK,
ADCLRC and DACLRC are outputs. The frequency of ADCLRC and DACLRC is set by the sample
rate control bits SR[4:0] and USB. In Slave mode BCLK, ADCLRC and DACLRC are inputs.
REGISTER
ADDRESS
R7 (07h)
Digital Audio
Interface
Format
BIT
LABEL
DEFAULT
DESCRIPTION
7
BCLKINV
0
BCLK invert bit (for master and slave
modes)
0 = BCLK not inverted
1 = BCLK inverted
6
MS
0
Master / Slave Mode Control
1 = Enable Master Mode
0 = Enable Slave Mode
5
LRSWAP
0
Left/Right channel swap
1 = swap left and right DAC data in
audio interface
0 = output left and right data as normal
4
LRP
0
right, left and i2s modes – LRCLK
polarity
1 = invert LRCLK polarity
0 = normal LRCLK polarity
DSP Mode – mode A/B select
1 = MSB is available on 1st BCLK rising
edge after LRC rising edge (mode B)
0 = MSB is available on 2nd BCLK rising
edge after LRC rising edge (mode A)
3:2
WL[1:0]
10
Audio Data Word Length
11 = 32 bits (see Note)
10 = 24 bits
01 = 20 bits
00 = 16 bits
1:0
FORMAT[1:0]
10
Audio Data Format Select
11 = DSP Mode
2
10 = I S Format
01 = Left justified
00 = Right justified
Table 34 Audio Data Format Control
Note: Right Justified mode does not support 32-bit data.
AUDIO INTERFACE OUTPUT TRISTATE
Register bit TRI, register 24(18h) bit[3] can be used to tristate the ADCDAT pin and switch ADCLRC,
DACLRC and BCLK to inputs. In Slave mode (MASTER=0) ADCLRC, DACLRC and BCLK are by
default configured as inputs and only ADCDAT will be tri-stated, (see Table 35).
REGISTER
ADDRESS
R24(18h)
Additional
Control (2)
BIT
LABEL
DEFAULT
3
TRI
0
DESCRIPTION
Tristates ADCDAT and switches ADCLRC,
DACLRC and BCLK to inputs.
0 = ADCDAT is an output, ADCLRC, DACLRC
and BCLK are inputs (slave mode) or outputs
(master mode)
1 = ADCDAT is tristated, ADCLRC, DACLRC
and BCLK are inputs
Table 35 Tri-stating the Audio Interface
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MASTER MODE ADCLRC AND DACLRC ENABLE
In Master mode, by default ADCLRC is disabled when the ADC is disabled and DACLRC is disabled
when the DAC is disabled. Register bit LRCM, register 24(18h) bit[2] changes the control so that the
ADCLRC and DACLRC are disabled only when ADC and DAC are disabled. This enables the user to
use e.g. ADCLRC for both ADC and DAC LRCLK and disable the ADC when DAC only operation is
required, (see Table 36).
REGISTER
ADDRESS
R24(18h)
Additional
Control (2)
BIT
LABEL
DEFAULT
2
LRCM
0
DESCRIPTION
Selects disable mode for ADCLRC and
DACLRC
0 = ADCLRC disabled when ADC (Left and
Right) disabled, DACLRC disabled when
DAC (Left and Right) disabled.
1 = ADCLRC and DACLRC disabled only when
ADC (Left and Right) and DAC (Left and
Right) are disabled.
Table 36 ADCLRC/DACLRC Enable
BIT CLOCK MODE
The default master mode bit clock generator produces a bit clock frequency based on the sample
rate and input MCLK frequency as shown in Table 40. When enabled by setting the appropriate
BCM[1:0] bits, the bit clock mode (BCM) function overrides the default master mode bit clock
generator to produce the bit clock frequency shown in the table below:
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
R8 (08h)
Clocking and
Sample Rate
Control
8:7
BCM[1:0]
00
DESCRIPTION
BCLK Frequency
00 = BCM function disabled
01 = MCLK/4
10 = MCLK/8
11 = MCLK/16
Table 37 Master Mode BCLK Frequency Control
The BCM mode bit clock generator produces 16 or 24 bit clock cycles per sample. The number of bit
clock cycles per sample in this mode is determined by the word length bits (WL[1:0]) in the Digital
Audio Interface Format register (R7). When these bits are set to 00, there will be 16 bit clock cycles
per sample. When these bits are set to 01, 10 or 11, there will be 24 bit clock cycles per sample.
Please refer to Figure 25.
The BCM generator uses the ADCLRC signal, hence the ADCLRC signal must be enabled when
using bit clock mode. To enable the ADCLRC signal, either the ADC must be powered up or, if the
ADC is not in use, the LRCM bit must be set to enable both the ADCLRC and DACLRC signals when
either the ADC or the DAC is enabled.
When the BCM function is enabled, the following restrictions apply:
1. The bit clock invert (BCLKINV) function is not available.
2. The DAC and ADC must be operated at the same sample rate.
3. DSP late digital audio interface mode is not available and must not be enabled.
Figure 25 Bit Clock Mode
Note: The shaded bit clock cycles are present only when 24-bit mode is selected. Please refer to the
"Bit Clock Mode" description for details.
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CLOCK OUTPUT
By default ADCLRC (pin 9) is the ADC word clock input/output. Under the control of ADCLRM[1:0],
register 27(1Bh) bits [8:7] the ADCLRC pin may be configured as a clock output. If ADCLRM is 01,
10 or 11 then ADCLRC pin is always an output even in slave mode or when TRI = ‘1’, (see Table 38).
The ADC then uses the DACLRC pin as its LRCLK in both master and slave modes.
REGISTER
ADDRESS
R27(1Bh)
Additional
Control (3)
BIT
LABEL
DEFAULT
[8:7] ADCLRM
[1:0]
00
DESCRIPTION
Configures ADCLRC pin
00 = ADCLRC is ADC word clock input (slave
mode) or ADCLRC output (master mode)
01 = ADCLRC pin is MCLK output
10 = ADCLRC pin is MCLK / 5.5 output
11 = ADCLRC pin is MCLK / 6 output
Table 38 ADCLRC Clock Output
CLOCKING AND SAMPLE RATES
The WM8750L supports a wide range of master clock frequencies on the MCLK pin, and can
generate many commonly used audio sample rates directly from the master clock. The ADC and
DAC do not need to run at the same sample rate; several different combinations are possible.
There are two clocking modes:
•
‘Normal’ mode supports master clocks of 128fs, 192fs, 256fs, 384fs, and their multiples
(Note: fs refers to the ADC or DAC sample rate, whichever is faster)
•
USB mode supports 12MHz or 24MHz master clocks. This mode is intended for use in
systems with a USB interface, and eliminates the need for an external PLL to generate
another clock frequency for the audio codec.
REGISTER
ADDRESS
R8 (08h)
Clocking and
Sample Rate
Control
BIT
LABEL
DEFAULT
DESCRIPTION
6
CLKDIV2
0
Master Clock Divide by 2
1 = MCLK is divided by 2
0 = MCLK is not divided
5:1
SR [4:0]
00000
Sample Rate Control
0
USB
0
Clocking Mode Select
1 = USB Mode
0 = ‘Normal’ Mode
Table 39 Clocking and Sample Rate Control
The clocking of the WM8750L is controlled using the CLKDIV2, USB, and SR control bits. Setting the
CLKDIV2 bit divides MCLK by two internally. The USB bit selects between ‘Normal’ and USB mode.
Each value of SR[4:0] selects one combination of MCLK division ratios and hence one combination
of sample rates (see next page). Since all sample rates are generated by dividing MCLK, their
accuracy depends on the accuracy of MCLK. If MCLK changes, the sample rates change
proportionately.
Note that some sample rates (e.g. 44.1kHz in USB mode) are approximated, i.e. they differ from their
target value by a very small amount. This is not audible, as the maximum deviation is only 0.27%
(8.0214kHz instead of 8kHz in USB mode). By comparison, a half-tone step corresponds to a 5.9%
change in pitch.
The SR[4:0] bits must be set to configure the appropriate ADC and DAC sample rates in both master
and slave mode.
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MCLK
CLKDIV2=0
MCLK
CLKDIV2=1
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ADC SAMPLE RATE
(ADCLRC)
DAC SAMPLE RATE
(DACLRC)
‘Normal’ Clock Mode (‘*’ indicates backward compatibility with WM8731)
8 kHz (MCLK/1536)
8 kHz (MCLK/1536)
24.576 MHz
8 kHz (MCLK/1536)
48 kHz (MCLK/256)
12 kHz (MCLK/1024)
12 kHz (MCLK/1024)
16 kHz (MCLK/768)
16 kHz (MCLK/768)
24 kHz (MCLK/512)
24 kHz (MCLK/512)
32 kHz (MCLK/384)
32 kHz (MCLK/384)
48 kHz (MCLK/256)
8 kHz (MCLK/1536)
48 kHz (MCLK/256)
48 kHz (MCLK/256)
96 kHz (MCLK/128)
96 kHz (MCLK/128)
8.0182 kHz (MCLK/1408)
8.0182 kHz (MCLK/1408)
11.2896MHz 22.5792MHz
8.0182 kHz (MCLK/1408)
44.1 kHz (MCLK/256)
11.025 kHz (MCLK/1024)
11.025 kHz (MCLK/1024)
22.05 kHz (MCLK/512)
22.05 kHz (MCLK/512)
44.1 kHz (MCLK/256)
8.0182 kHz (MCLK/1408)
44.1 kHz (MCLK/256)
44.1 kHz (MCLK/256)
88.2 kHz (MCLK/128)
88.2 kHz (MCLK/128)
8 kHz (MCLK/2304)
8 kHz (MCLK/2304)
18.432MHz 36.864MHz
8 kHz (MCLK/2304)
48 kHz (MCLK/384)
12 kHz (MCLK/1536)
12 kHz (MCLK/1536)
16kHz (MCLK/1152)
16 kHz (MCLK/1152)
24kHz (MCLK/768)
24 kHz (MCLK/768)
32 kHz (MCLK/576)
32 kHz (MCLK/576)
48 kHz (MCLK/384)
48 kHz (MCLK/384)
48 kHz (MCLK/384)
8 kHz (MCLK/2304)
96 kHz (MCLK/192)
96 kHz (MCLK/192)
8.0182 kHz (MCLK/2112)
8.0182 kHz (MCLK/2112)
16.9344MHz 33.8688MHz
8.0182 kHz (MCLK/2112)
44.1 kHz (MCLK/384)
11.025 kHz (MCLK/1536)
11.025 kHz (MCLK/1536)
22.05 kHz (MCLK/768)
22.05 kHz (MCLK/768)
44.1 kHz (MCLK/384)
8.0182 kHz (MCLK/2112)
44.1 kHz (MCLK/384)
44.1 kHz (MCLK/384)
88.2 kHz (MCLK/192)
88.2 kHz (MCLK/192)
USB Mode (‘*’ indicates backward compatibility with WM8731)
8 kHz (MCLK/1500)
8 kHz (MCLK/1500)
12.000MHz 24.000MHz
8 kHz (MCLK/1500)
48 kHz (MCLK/250)
8.0214 kHz (MCLK/1496)
8.0214kHz (MCLK/1496)
8.0214 kHz (MCLK/1496)
44.118 kHz (MCLK/272)
11.0259 kHz (MCLK/1088)
11.0259kHz (MCLK/1088)
12 kHz (MCLK/1000)
12 kHz (MCLK/1000)
16kHz (MCLK/750)
16kHz (MCLK/750)
22.0588kHz (MCLK/544)
22.0588kHz (MCLK/544)
24kHz (MCLK/500)
24kHz (MCLK/500)
32 kHz (MCLK/375)
32 kHz (MCLK/375)
44.118 kHz (MCLK/272)
8.0214kHz (MCLK/1496)
44.118 kHz (MCLK/272)
44.118 kHz (MCLK/272)
48 kHz (MCLK/250)
8 kHz (MCLK/1500)
48 kHz (MCLK/250)
48 kHz (MCLK/250)
88.235kHz (MCLK/136)
88.235kHz (MCLK/136)
96 kHz (MCLK/125)
96 kHz (MCLK/125)
12.288 MHz
USB
SR [4:0]
FILTER
TYPE
BCLK
(MS=1)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00110 *
00100 *
01000
01010
11100
01100 *
00010 *
00000 *
01110 *
10110 *
10100 *
11000
11010
10010 *
10000 *
11110 *
00111 *
00101 *
01001
01011
11101
01101 *
00001 *
00011 *
01111 *
10111 *
10101 *
11001
11011
10011 *
10001 *
11111 *
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
3
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/2
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/4
MCLK/2
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/3
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/6
MCLK/3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
00110 *
00100 *
10111 *
10101 *
11001
01000
01010
11011
11100
01100 *
10011 *
10001 *
00010 *
00000 *
11111 *
01110 *
0
0
1
1
1
0
0
1
0
0
1
1
0
0
3
2
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
MCLK
Table 40 Master Clock and Sample Rates
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CONTROL INTERFACE
SELECTION OF CONTROL MODE
The WM8750L is controlled by writing to registers through a serial control interface. A control word
consists of 16 bits. The first 7 bits (B15 to B9) are address bits that select which control register is
accessed. The remaining 9 bits (B8 to B0) are data bits, corresponding to the 9 bits in each control
register. The control interface can operate as either a 3-wire or 2-wire MPU interface. The MODE pin
selects the interface format.
MODE
INTERFACE FORMAT
Low
2 wire
High
3 wire
Table 41 Control Interface Mode Selection
3-WIRE SERIAL CONTROL MODE
In 3-wire mode, every rising edge of SCLK clocks in one data bit from the SDIN pin. A rising edge on
CSB latches in a complete control word consisting of the last 16 bits.
latch
CSB
SCLK
SDIN
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
control register address
B5
B4
B3
B2
B1
B0
control register data bits
Figure 26 3-Wire Serial Control Interface
2-WIRE SERIAL CONTROL MODE
The WM8750L supports software control via a 2-wire serial bus. Many devices can be controlled by
the same bus, and each device has a unique 7-bit address (this is not the same as the 7-bit address
of each register in the WM8750L).
The WM8750L operates as a slave device only. The controller indicates the start of data transfer with
a high to low transition on SDIN while SCLK remains high. This indicates that a device address and
data will follow. All devices on the 2-wire bus respond to the start condition and shift in the next eight
bits on SDIN (7-bit address + Read/Write bit, MSB first). If the device address received matches the
address of the WM8750L and the R/W bit is ‘0’, indicating a write, then the WM8750L responds by
pulling SDIN low on the next clock pulse (ACK). If the address is not recognised or the R/W bit is ‘1’,
the WM8750L returns to the idle condition and wait for a new start condition and valid address.
Once the WM8750L has acknowledged a correct address, the controller sends the first byte of
control data (B15 to B8, i.e. the WM8750L register address plus the first bit of register data). The
WM8750L then acknowledges the first data byte by pulling SDIN low for one clock pulse. The
controller then sends the second byte of control data (B7 to B0, i.e. the remaining 8 bits of register
data), and the WM8750L acknowledges again by pulling SDIN low.
The transfer of data is complete when there is a low to high transition on SDIN while SCLK is high.
After receiving a complete address and data sequence the WM8750L returns to the idle state and
waits for another start condition. If a start or stop condition is detected out of sequence at any point
during data transfer (i.e. SDIN changes while SCLK is high), the device jumps to the idle condition.
DEVICE ADDRESS
(7 BITS)
SDIN
RD / WR
BIT
ACK
(LOW)
CONTROL BYTE 1
(BITS 15 TO 8)
ACK
(LOW)
CONTROL BYTE 2
(BITS 7 TO 0)
ACK
(LOW)
SCLK
START
register address and
1st register data bit
remaining 8 bits of
register data
STOP
Figure 27 2-Wire Serial Control Interface
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The WM8750L has two possible device addresses, which can be selected using the CSB pin.
CSB STATE
DEVICE ADDRESS
Low
0011010 (0 x 34h)
High
0011011 (0 x 36h)
Table 42 2-Wire MPU Interface Address Selection
POWER SUPPLIES
The WM8750L can use up to four separate power supplies:
•
•
•
•
AVDD / AGND: Analogue supply, powers all analogue functions except the headphone drivers.
AVDD can range from 1.8V to 3.6V and has the most significant impact on overall power
consumption (except for power consumed in the headphone). A large AVDD slightly improves
audio quality.
HPVDD / HPGND: Headphone supply, powers the headphone drivers. HPVDD is normally tied
to AVDD, but it requires separate layout and decoupling capacitors to curb harmonic distortion.
If HPVDD is lower than AVDD, the output signal may be clipped.
DCVDD: Digital core supply, powers all digital functions except the audio and control
interfaces. DCVDD can range from 1.42V to 3.6V, and has no effect on audio quality. The
return path for DCVDD is DGND, which is shared with DBVDD.
DBVDD: Digital buffer supply, powers the audio and control interface buffers. This makes it
possible to run the digital core at very low voltages, saving power, while interfacing to other
digital devices using a higher voltage. DBVDD draws much less power than DCVDD, and has
no effect on audio quality. DBVDD can range from 1.8V to 3.6V. The return path for DBVDD is
DGND, which is shared with DCVDD.
It is possible to use the same supply voltage on all four. However, digital and analogue supplies
should be routed and decoupled separately to keep digital switching noise out of the analogue signal
paths.
POWER MANAGEMENT
The WM8750L has two control registers that allow users to select which functions are active. For
minimum power consumption, unused functions should be disabled. To avoid any pop or click noise,
it is important to enable or disable functions in the correct order (see Applications Information).
VMIDSEL is the enable for the Vmid reference, which defaults to disabled and can be enabled as a
50kΩ potential divider or, for low power maintenance of Vref when all other blocks are disabled, as a
500kΩ potential divider.
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REGISTER
ADDRESS
R25 (19h)
Power
Management
(1)
R26 (1Ah)
Power
Management
(2)
BIT
LABEL
DEFAULT
DESCRIPTION
8:7
VMIDSEL
00
Vmid divider enable and select
00 – Vmid disabled (for OFF mode)
01 – 50kΩ divider enabled (for
playback/record)
10 – 500kΩ divider enabled (for low-power
standby)
11 – 5kΩ divider enabled (for fast start-up)
6
VREF
0
VREF (necessary for all other functions)
0 = Power down
1 = Power up
5
AINL
0
Analogue in PGA Left
0 = Power down
1 = Power up
4
AINR
0
Analogue in PGA Right
0 = Power down
1 = Power up
3
ADCL
0
ADC Left
0 = Power down
1 = Power up
2
ADCR
0
ADC Right
0 = Power down
1 = Power up
1
MICB
0
MICBIAS
0 = Power down
1 = Power up
8
DACL
0
DAC Left
0 = Power down
1 = Power up
7
DACR
0
DAC Right
0 = Power down
1 = Power up
6
LOUT1
0
LOUT1 Output Buffer*
0 = Power down
1 = Power up
5
ROUT1
0
ROUT1 Output Buffer*
0 = Power down
1 = Power up
4
LOUT2
0
LOUT2 Output Buffer*
0 = Power down
1 = Power up
3
ROUT2
0
ROUT2 Output Buffer*
0 = Power down
1 = Power up
2
MONO
0
MONOOUT Output Buffer and Mono Mixer
0 = Power down
1 = Power up
1
OUT3
0
OUT3 Output Buffer
0 = Power down
1 = Power up
* The left mixer is enabled when LOUT1=1 or LOUT2=1. The right mixer is enabled when
ROUT1=1 or ROUT2=1.
Table 43 Power Management
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STOPPING THE MASTER CLOCK
In order to minimise power consumed in the digital core of the WM8750L, the master clock may be
stopped in Standby and OFF modes. If this cannot be done externally at the clock source, the
DIGENB bit (R25, bit 0) can be set to stop the MCLK signal from propagating into the device core. In
Standby mode, setting DIGENB will typically provide an additional power saving on DCVDD of 20uA.
However, since setting DIGENB has no effect on the power consumption of other system
components external to the WM8750L, it is preferable to disable the master clock at its source
wherever possible.
REGISTER
ADDRESS
BIT
R25 (19h)
Additional Control
(1)
0
LABEL
DIGENB
DEFAULT
0
DESCRIPTION
Master clock disable
0: master clock enabled
1: master clock disabled
Table 44 ADC and DAC Oversampling Rate Selection
NOTE: Before DIGENB can be set, the control bits ADCL, ADCR, DACL and DACR must be set
to zero and a waiting time of 1ms must be observed. Any failure to follow this procedure may
prevent DACs and ADCs from re-starting correctly.
SAVING POWER BY REDUCING OVERSAMPLING RATE
The default mode of operation of the ADC and DAC digital filters is in 128x oversampling mode.
Under the control of ADCOSR and DACOSR the oversampling rate may be halved. This will result in
a slight decrease in noise performance but will also reduce the power consumption of the device. In
USB mode ADCOSR must be set to 0, i.e. 128x oversampling.
REGISTER
ADDRESS
BIT
R24 (18h)
Additional Control
(2)
LABEL
DEFAULT
DESCRIPTION
1
ADCOSR
0
ADC oversample rate select
1 = 64x (lowest power)
0 = 128x (best SNR)
0
DACOSR
0
DAC oversample rate select
1 = 64x (lowest power)
0 = 128x (best SNR)
Table 45 ADC and DAC Oversampling Rate Selection
ADCOSR set to ‘1’, 64x oversample mode, is not supported in USB mode (USB=1).
SAVING POWER AT HIGHER SUPPLY VOLTAGES
The analogue supplies to the WM8750L can run from 1.8V to 3.6V. By default, all analogue circuitry
on the device is optimized to run at 3.3V. This set-up is also good for all other supply voltages down
to 1.8V. At lower voltages, performance can be improved by increasing the bias current. If low
power operation is preferred the bias current can be left at the default setting. This is controlled as
shown below.
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REGISTER
ADDRESS
BIT
LABEL
R23 (17h)
Additional
Control(1)
7:6
VSEL
[1:0]
DEFAULT
11
DESCRIPTION
Analogue Bias optimization
00: Highest bias current, optimized for
AVDD=1.8V
01: Bias current optimized for AVDD=2.5V
1X: Lowest bias current, optimized for AVDD=3.3V
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REGISTER MAP
ADDRESS
REGISTER
remarks
Bit[8]
Bit[7]
Bit[6]
LIVU
LINMUTE
LIZC
RIZC
Bit[5]
Bit[4]
Bit[3]
Bit[2]
Bit[1]
Bit[0]
default
page ref
010010111
21
(Bit 15 – 9)
R0 (00h)
0000000
Left Input volume
LINVOL
R1 (01h)
0000001
Right Input volume
RIVU
RINMUTE
010010111
21
R2 (02h)
0000010
LOUT1 volume
LO1VU
LO1ZC
LOUT1VOL[6:0]
001111001
34
R3 (03h)
0000011
ROUT1 volume
RO1VU
RO1ZC
ROUT1VOL[6:0]
001111001
34
R4 (04h)
0000100
Reserved
0
0
RINVOL
0
ADCDIV2 DACDIV2
0
0
0
R5 (05h)
0000101
ADC & DAC Control
HPOR
DACMU
R6 (06h)
0000110
Reserved
0
0
0
0
0
0
R7 (07h)
0000111
Audio Interface
0
BCLKINV
MS
LRSWAP
LRP
R8 (08h)
0001000
Sample rate
R9 (09h)
0001001
Reserved
0
0
BCM[1:0]
0
ADCPOL[1:0]
0
DEEMPH[1:0]
0
-
ADCHPD
000001000
21,28,31
0
000000000
-
000001010
43
USB
000000000
45
0
000000000
-
0
0
WL[1:0]
CLKDIV2
0
000000000
0
FORMAT[1:0]
SR[4:0]
0
0
0
0
R10 (0Ah)
0001010
Left DAC volume
LDVU
LDACVOL[7:0]
011111111
29
R11 (0Bh)
0001011
Right DAC volume
RDVU
RDACVOL[7:0]
011111111
29
R12 (0Ch)
0001100
Bass control
0
BB
BC
0
0
BASS[3:0]
000001111
30
R13 (0Dh)
0001101
Treble control
0
0
TC
0
0
TRBL[3:0]
000001111
30
R15 (0Fh)
0001111
Reset
not reset
-
R16 (10h)
0010000
3D control
R17 (11h)
0010001
ALC1
ALCSEL[1:0]
R18 (12h)
0010010
ALC2
0
R19 (13h)
0010011
ALC3
0
R20 (14h)
0010100
Noise Gate
0
writing to this register resets all registers to their default state
0
MODE3D
ALCZC
3DUC
3DLC
0
000000000
28
ALCL[3:0]
001111011
26
HLD[3:0]
000000000
26
ATK[3:0]
000110010
26
000000000
27
24
3DDEPTH[3:0]
MAXGAIN[2:0]
0
0
DCY[3:0]
NGTH[4:0]
3DEN
NGG[1:0]
NGAT
R21 (15h)
0010101
Left ADC volume
LAVU
LADCVOL[7:0]
011000011
R22 (16h)
0010110
Right ADC volume
RAVU
RADCVOL[7:0]
011000011
24
R23 (17h)
0010111
Additional control(1)
TSDEN
R24 (18h)
0011000
Additional control(2)
OUT3SW[1:0]
R25 (19h)
0011001
Pwr Mgmt (1)
VMIDSEL[1:0]
R26 (1Ah)
0011010
Pwr Mgmt (2)
R27 (1Bh)
0011011
Additional Control (3)
R31 (1Fh)
0011111
ADC input mode
DS
MONOMIX[1:0]
R32 (20h)
0100000
ADCL signal path
0
R33 (21h)
0100001
ADCR signal path
0
R34 (22h)
0100010
Left out Mix (1)
LD2LO
LI2LO
LI2LOVOL[2:0]
0
R35 (23h)
0100011
Left out Mix (2)
RD2LO
RI2LO
RI2LOVOL[2:0]
0
R36 (24h)
0100100
Right out Mix (1)
LD2RO
LI2RO
LI2ROVOL[2:0]
0
R37 (25h)
0100101
Right out Mix (2)
RD2RO
RI2RO
RI2ROVOL[2:0]
0
0
DACL
VSEL[1:0]
DMONOMIX[1:0]
HPSWEN HPSWPOL ROUT2INV
DATSEL[1:0]
DACINV
TOEN
011000000
20,21,31,38
TRI
LRCM
ADCOSR
DACOSR
000000000
35, 37,50
AINL
AINR
ADCL
ADCR
MICB
DIGENB
000000000
49
LOUT1
ROUT1
LOUT2
ROUT2
MONO
OUT3
0
000000000
49
VROI
HPFLREN
0
0
0
0
0
000000000
35
RDCM
LDCM
0
0
0
0
000000000
19
LINSEL[1:0]
LMICBOOST[1:0]
0
0
0
0
000000000
19
RINSEL[1:0]
RMICBOOST[1:0]
0
0
0
0
000000000
19
001010000
32
001010000
32
001010000
33
001010000
33
DACR
ADCLRM[1:0]
VREF
LMIXSEL[2:0]
0
0
0
RMIXSEL[2:0]
0
0
R38 (26h)
0100110
Mono out Mix (1)
LD2MO
LI2MO
LI2MOVOL[2:0]
0
0
0
0
001010000
33
R39 (27h)
0100111
Mono out Mix (2)
RD2MO
RI2MO
RI2MOVOL[2:0]
0
0
0
0
001010000
33
R40 (28h)
0101000
LOUT2 volume
LO2VU
LO2ZC
LOUT2VOL[6:0]
001111001
35
R41 (29h)
0101001
ROUT2 volume
RO2VU
RO2ZC
ROUT2VOL[6:0]
001111001
35
R42 (2Ah)
0101010
MONOOUT volume
0
MOZC
MOUTVOL[6:0]
001111001
35
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DIGITAL FILTER CHARACTERISTICS
The ADC and DAC employ different digital filters. There are 4 types of digital filter, called Type 0, 1, 2
and 3. The performance of Types 0 and 1 is listed in the table below, the responses of all filters is
shown in the proceeding pages.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ADC Filter Type 0 (USB Mode, 250fs operation)
Passband
+/- 0.05dB
0
-6dB
0.416fs
0.5fs
Passband Ripple
+/- 0.05
Stopband
dB
0.584fs
Stopband Attenuation
f > 0.584fs
-60
dB
ADC Filter Type 1 (USB mode, 272fs or Normal mode operation)
Passband
+/- 0.05dB
0
-6dB
0.4535fs
0.5fs
Passband Ripple
+/- 0.05
Stopband
dB
0.5465fs
Stopband Attenuation
f > 0.5465fs
High Pass Filter Corner
Frequency
-60
dB
-3dB
3.7
-0.5dB
10.4
-0.1dB
21.6
Hz
DAC Filter Type 0 (USB mode, 250fs operation)
Passband
+/- 0.03dB
0
-6dB
0.416fs
0.5fs
Passband Ripple
+/-0.03
Stopband
dB
0.584fs
Stopband Attenuation
f > 0.584fs
-50
dB
DAC Filter Type 1 (USB mode, 272fs or Normal mode operation)
Passband
+/- 0.03dB
0
-6dB
0.4535fs
0.5fs
Passband Ripple
+/- 0.03
Stopband
dB
0.5465fs
Stopband Attenuation
f > 0.5465fs
-50
dB
Table 46 Digital Filter Characteristics
DAC FILTERS
ADC FILTERS
Mode
Group Delay
Mode
0 (250 USB)
11/FS
0 (250 USB)
Group Delay
13/FS
1 (256/272)
16/FS
1 (256/272)
23/FS
2 (250 USB, 96k mode)
4/FS
2 (250 USB, 96k mode)
4/FS
3 (256/272, 88.2/96k mode)
3/FS
3 (256/272, 88.2/96k mode)
5/FS
Table 47 ADC/DAC Digital Filters Group Delay
TERMINOLOGY
1.
Stop Band Attenuation (dB) – the degree to which the frequency spectrum is attenuated (outside audio band)
2.
Pass-band Ripple – any variation of the frequency response in the pass-band region
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DAC FILTER RESPONSES
0.02
0
0.01
0
Response (dB)
Response (dB)
-20
-40
-60
-0.01
-0.02
-0.03
-0.04
-80
-0.05
-100
0
0.5
1
1.5
Frequency (Fs)
2
2.5
3
-0.06
0
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (Fs)
0.35
0.4
0.45
0.5
0.4
0.45
0.5
Figure 28 DAC Digital Filter Frequency Response – Type 0 Figure 29 DAC Digital Filter Ripple – Type 0
0.02
0
0.01
0
Response (dB)
Response (dB)
-20
-40
-60
-0.01
-0.02
-0.03
-0.04
-80
-0.05
-0.06
-100
0
0.5
1
1.5
Frequency (Fs)
2
2.5
0
3
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (Fs)
0.35
Figure 30 DAC Digital Filter Frequency Response – Type 1 Figure 31 DAC Digital Filter Ripple – Type 1
0.02
0
0.01
0
Response (dB)
Response (dB)
-20
-40
-60
-0.01
-0.02
-0.03
-0.04
-80
-0.05
-0.06
-100
0
0.5
1
1.5
Frequency (Fs)
2
2.5
3
0
0.05
0.1
0.15
Frequency (Fs)
0.2
0.25
Figure 32 DAC Digital Filter Frequency Response – Type 2 Figure 33 DAC Digital Filter Ripple – Type 2
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0.25
0
0.2
0.15
-20
Response (dB)
Response (dB)
0.1
-40
-60
0.05
0
-0.05
-0.1
-80
-0.15
-100
-0.25
-0.2
0
0.5
1
1.5
Frequency (Fs)
2
2.5
3
0
0.05
0.1
0.15
Frequency (Fs)
0.2
0.25
Figure 34 DAC Digital Filter Frequency Response – Type 3 Figure 35 DAC Digital Filter Ripple – Type 3
ADC FILTER RESPONSES
0.04
0
0.03
0.02
Response (dB)
Response (dB)
-20
-40
-60
0.01
0
-0.01
-0.02
-80
-0.03
-100
0
0.5
1
1.5
Frequency (Fs)
2
2.5
-0.04
3
0
Figure 36 ADC Digital Filter Frequency Response – Type 0
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (Fs)
0.35
0.4
0.45
0.5
Figure 37 ADC Digital Filter Ripple – Type 0
0.02
0
0.01
0
Response (dB)
Response (dB)
-20
-40
-60
-0.01
-0.02
-0.03
-0.04
-80
-0.05
-0.06
-100
0
0.5
1
1.5
Frequency (Fs)
2
2.5
Figure 38 ADC Digital Filter Frequency Response – Type 1
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3
0
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (Fs)
0.35
0.4
0.45
0.5
Figure 39 ADC Digital Filter Ripple – Type 1
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0.25
0
0.2
0.15
-20
Response (dB)
Response (dB)
0.1
-40
-60
0.05
0
-0.05
-0.1
-80
-0.15
-100
-0.25
-0.2
0
0.5
1
1.5
Frequency (Fs)
2
2.5
3
0
Figure 40 ADC Digital Filter Frequency Response – Type 2
0.05
0.1
0.15
Frequency (Fs)
0.2
0.25
Figure 41 ADC Digital Filter Ripple – Type 2
0.25
0
0.2
0.15
-20
Response (dB)
Response (dB)
0.1
-40
-60
0.05
0
-0.05
-0.1
-80
-0.15
-100
-0.25
-0.2
0
0.5
1
1.5
Frequency (Fs)
2
2.5
0
3
Figure 42 ADC Digital Filter Frequency Response – Type 2
0.05
0.1
0.15
Frequency (Fs)
0.2
0.25
Figure 43 ADC Digital Filter Ripple – Type 3
DE-EMPHASIS FILTER RESPONSES
0.4
0
0.3
-2
Response (dB)
Response (dB)
0.2
-4
-6
0.1
0
-0.1
-0.2
-8
-0.3
-0.4
-10
0
2000
4000
6000
8000
10000
Frequency (Fs)
12000
14000
Figure 44 De-emphasis Frequency Response (32kHz)
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16000
0
2000
4000
6000
8000
10000
Frequency (Fs)
12000
14000
16000
Figure 45 De-emphasis Error (32kHz)
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0.4
0
0.3
-2
Response (dB)
Response (dB)
0.2
-4
-6
0.1
0
-0.1
-0.2
-8
-0.3
-0.4
-10
0
5000
10000
Frequency (Fs)
15000
0
20000
Figure 46 De-emphasis Frequency Response (44.1kHz)
5000
10000
Frequency (Fs)
15000
20000
15000
20000
Figure 47 De-emphasis Error (44.1kHz)
0.4
0
0.3
-2
Response (dB)
Response (dB)
0.2
-4
-6
0.1
0
-0.1
-0.2
-8
-0.3
-0.4
-10
0
5000
10000
Frequency (Fs)
15000
0
20000
Figure 48 De-emphasis Frequency Response (48kHz)
5000
10000
Frequency (Fs)
Figure 49 De-emphasis Error (48kHz)
HIGHPASS FILTER
The WM8750L has a selectable digital highpass filter in the ADC filter path to remove DC offsets. The filter response is
characterised by the following polynomial:
H(z) =
1 - z-1
1 - 0.9995z-1
Response (dB)
0
-5
-10
-15
0
0.0005
0.001
Frequency (Fs)
0.0015
0.002
Figure 50 ADC Highpass Filter Response
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WM8750L
APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
Figure 51 Recommended External Components Diagram
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LINE INPUT CONFIGURATION
When LINPUT1/RINPUT1 or LINPUT2/RINPUT2 are used as line inputs, the microphone boost and
ALC functions should normally be disabled.
In order to avoid clipping, the user must ensure that the input signal does not exceed AVDD. This
may require a potential divider circuit in some applications. It is also recommended to remove RF
interference picked up on any cables using a simple first-order RC filter, as high-frequency
components in the input signal may otherwise cause aliasing distortion in the audio band. AC signals
with no DC bias should be fed to the WM8750L through a DC blocking capacitor, e.g. 1µF.
MICROPHONE INPUT CONFIGURATION
MICBIAS
R1
680 Ohm to 2.2kOhm
check microphone's specification
FROM
MICROPHONE
C2
1uF
LINPUT1/2/3
RINPUT1/2/3
AGND
R2
47kOhm
AGND
C1
220pF
AGND
Figure 52 Recommended Circuit for Line Input
For interfacing to a microphone, the ALC function should be enabled and the microphone boost
switched on. Microphones held close to a speaker’s mouth would normally use the 13dB gain setting,
while tabletop or room microphones would need a 29dB boost.
The recommended application circuit is shown above. R1 and R2 form part of the biasing network
(refer to Microphone Bias section). R1 connected to MICBIAS is necessary only for electret type
microphones that require a voltage bias. R2 should always be present to prevent the microphone
input from charging to a high voltage which may damage the microphone on connection. R1 and R2
should be large so as not to attenuate the signal from the microphone, which can have source
impedance greater than 2kOhm. C1 together with the source impedance of the microphone and the
WM8750L input impedance forms an RF filter. C2 is a DC blocking capacitor to allow the microphone
to be biased at a different DC voltage to the MICIN signal.
MINIMISING POP NOISE AT THE ANALOGUE OUTPUTS
To minimise any pop or click noise when the system is powered up or down, the following procedures
are recommended.
POWER UP
•
•
•
Switch on power supplies. By default the WM8750L is in Standby Mode, the DAC is
digitally muted and the Audio Interface, Line outputs and Headphone outputs are all OFF
(DACMU = 1 Power Management registers 1 and 2 are all zeros).
Enable Vmid and VREF.
Enable DACs as required
•
•
Enable line and / or headphone output buffers as required.
Set DACMU = 0 to soft-un-mute the audio DACs.
POWER DOWN
w
•
Set DACMU = 1 to soft-mute the audio DACs.
•
•
Disable all output buffers.
Switch off the power supplies.
PD Rev 4.2 August 2005
58
WM8750L
Production Data
POWER MANAGEMENT EXAMPLES
AINL/R
POWER MANAGEMENT (1)
VREF
OPERATION MODE
PGAs
POWER MANAGEMENT (2)
ADCs
PGL PGR ADL
DACs
Output Buffers
ADR
MBI
DAL
DAR
LO1
RO1
LO2
RO2
MO
HPD
Stereo Headphone Playback
1
0
0
0
0
0
0
1
1
1
1
0
0
0
x
Stereo Line-in Record
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
Stereo Microphone Record
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
Mono Microphone Record
1
1
1
0
1
0
1
0
0
0
0
0
0
0
0
Stereo Line-in to Headphone Out
1
1
0
0
0
0
0
0
0
1
1
0
0
0
x
Phone Call
1
1
1
0
0
0
1
0
0
1
1
0
0
1
x
Speaker Phone Call [ROUT2INV = 1]
1
1
1
0
0
0
1
0
0
0
0
1
1
1
0
Record Phone Call [L channel = mic with
boost, R channel = RX, enable mono mix]
1
1
1
1
1
1
1
0
0
1
1
0
0
1
x
Table 48 Register Settings for Power Management
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WM8750L
Production Data
PACKAGE DIMENSIONS
FL: 32 PIN QFN PLASTIC PACKAGE 5 X 5 X 0.9 mm BODY, 0.50 mm LEAD PITCH
CORNER
TIE BAR
5
DM030.E
SEE DETAIL A
D2
D
B
D2/2
25
32
L
1
24
INDEX AREA
(D/2 X E/2)
EXPOSED
GROUND 6
PADDLE
E2/2
A
E2
17
E
SEE DETAIL B
8
aaa C
2X
16
15
9
b
2X
B
e
aaa C
TOP VIEW
BOTTOM VIEW
DETAIL A
ccc C
(A3)
1
A
1
CORNER
TIE BAR
5
32x b
0.08 C
bbb M C A B
A1
SIDE VIEW
SEATING PLANE
L
C
0.
1
e/2 TERMINAL TIP
m
m
0.5
m
m
EXPOSED
GROUND
PADDLE
R
32x K
66
DATUM
43
DETAIL B
1
Symbols
A
A1
A3
b
D
D2
E
E2
e
L
L1
R
K
aaa
bbb
ccc
REF:
MIN
0.85
0
0.18
4.90
3.2
4.90
3.2
0.35
L1
R
e
L1
Dimensions (mm)
NOM
MAX
0.90
1.00
0.02
0.05
0.2 REF
0.23
0.30
5.00
5.10
3.3
3.4
5.00
5.10
3.3
3.4
0.5 BSC
0.4
0.45
0.1
NOTE
1
2
2
1
b(min)/2
0.20
Tolerances of Form and Position
0.15
0.10
0.10
JEDEC, MO-220, VARIATION VHHD-2
NOTES:
1. DIMENSION b APPLIED TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. DIMENSION L1 REPRESENTS TERMINAL PULL BACK FROM
PACKAGE SIDE WALL. MAXIMUM OF 0.1mm IS ACCEPTABLE. WHERE TERMINAL PULL BACK EXISTS, ONLY UPPER HALF OF LEAD IS VISIBLE ON PACKAGE SIDE WALL DUE TO HALF
ETCHING OF LEADFRAME.
2. FALLS WITHIN JEDEC, MO-220 WITH THE EXCEPTION OF D2, E2:
D2,E2: LARGER PAD SIZE CHOSEN WHICH IS JUST OUTSIDE JEDEC SPECIFICATION
3. ALL DIMENSIONS ARE IN MILLIMETRES
4. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE.
5. SHAPE AND SIZE OF CORNER TIE BAR MAY VARY WITH PACKAGE TERMINAL COUNT. CORNER TIE BAR IS CONNECTED TO EXPOSED PAD INTERNALLY.
6. REFER TO APPLICATION NOTE WAN_0118 FOR FURTHER INFORMATION REGARDING PCB FOOTPRINTS AND QFN PACKAGE SOLDERING.
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PD Rev 4.2 August 2005
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Production Data
WM8750L
IMPORTANT NOTICE
Wolfson Microelectronics plc (WM) reserve the right to make changes to their products or to discontinue any product or
service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing
orders, that information being relied on is current. All products are sold subject to the WM terms and conditions of sale
supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation
of liability.
WM warrants performance of its products to the specifications applicable at the time of sale in accordance with WM’s
standard warranty. Testing and other quality control techniques are utilised to the extent WM deems necessary to support
this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by
government requirements.
In order to minimise risks associated with customer applications, adequate design and operating safeguards must be used
by the customer to minimise inherent or procedural hazards. Wolfson products are not authorised for use as critical
components in life support devices or systems without the express written approval of an officer of the company. Life
support devices or systems are devices or systems that are intended for surgical implant into the body, or support or
sustain life, and whose failure to perform when properly used in accordance with instructions for use provided, can be
reasonably expected to result in a significant injury to the user. A critical component is any component of a life support
device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
WM assumes no liability for applications assistance or customer product design. WM does not warrant or represent that
any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual
property right of WM covering or relating to any combination, machine, or process in which such products or services might
be or are used. WM’s publication of information regarding any third party’s products or services does not constitute WM’s
approval, license, warranty or endorsement thereof.
Reproduction of information from the WM web site or datasheets is permissible only if reproduction is without alteration and
is accompanied by all associated warranties, conditions, limitations and notices. Representation or reproduction of this
information with alteration voids all warranties provided for an associated WM product or service, is an unfair and deceptive
business practice, and WM is not responsible nor liable for any such use.
Resale of WM’s products or services with statements different from or beyond the parameters stated by WM for that
product or service voids all express and any implied warranties for the associated WM product or service, is an unfair and
deceptive business practice, and WM is not responsible nor liable for any such use.
ADDRESS
Wolfson Microelectronics plc
Westfield House
26 Westfield Road
Edinburgh
EH11 2QB
United Kingdom
Tel :: +44 (0)131 272 7000
Fax :: +44 (0)131 272 7001
Email :: [email protected]
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WM8750L
Production Data
Revision History
DATE
RELEASE
May 2002
18 Sept
2002
Rev 1.5
Rev 1.62
DESCRIPTION OF CHANGES
PAGES
Added Power Management section
36, 39
Added MICBIAS off switch
12
Modified ADC mono mixing
12
Moved and clarified 3D enhance function
19
Updated register map
38
Pinout
2
Added differential input option
1, 11
Added DATSEL function
13
Updated register map
26 Sept
2002
2 Oct 2002
9 Oct 2002
15 Nov 2002
Rev 1.63
Rev 1.64
Rev 1.65
Rev 1.7
41
Added filter characteristics
42-45
Thermal Shutdown added
30
Headset Switch added
31
ADCDIV2 and DACDIV2 control bits added
21
Separate DAC and ADC 3D filters removed – 3D now available on DAC or ADC
21
VSEL register and description added
31
ROUT2 invert added
30
MONOMIX register description updated
13
VMIDSEL Vmid divider select added
42
Added DSP mode diagram and modified LRP description
36,38
Updated table for DACMONOMIX
25
Register Map address for 3D corrected
44
LIVU & RIVU named correctly and description updated in table 8
15
DACINV DAC phase invert description added
25
BCLKINV bit added
38
Added page references to register map
44
De-emphasis & Highpass filter characteristics added
19 Nov 2002
Rev 1.71
48-49
Max. soldering temperature raised to 260°C
3
Updated package diagram
51
22 Nov 2002
Rev 1.72
Updated package diagram (dimensions A, D, D2, E, E2)
20 Jan 2003
Rev 1.73
Updated THD/output power data, inserted THD vs power graphs
51
1, 5, 6
Updated power consumption data
1, 7
L/RMICBOOST function corrected (added 20dB gain)
13
Mixer Gains inverted
27, 28
L/RINMUTE: added note saying L/RIVU must be set for un-muting
16
22 Jan 2003
Rev 1.74
Updated THD versus output power graphs
11 Feb 2003
Rev 1.75
Added line-out modification: updated block diagram, OUT3 description, line-out
description and diagram
6
Order Codes: Tape and reel + lead free options added
2
Pin Description, pin 9
2
Electrical Characteristics, Headphone Output
5
Headphone/Speaker Output
6
Power Consumption
7
3D Stereo Enhancement, Important Note added
21
Headphone Switch, note added
29
LINEOUTPUT
31
Audio Interface Output Tri-state, Master Mode ADCLRC/DACLRC Enable and
Clock Output added
37
Power Management Table
37
Added recommended external components diagram and description
Updated package diagram
Rev 1.76
w
34,35
2-Wire Serial Control Interface, Fig 18 and Table 36 updates
Register Map, R27 added, R20 and R24 updated
27 Feb 2003
1, 29, 32
Added VROI bit and description
40
48, 49
50
29, 41
PD Rev 4.2 August 2005
62