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DESCRIPTION
The WM8740 is a very high performance stereo DAC designed for audio applications such as CD, DVD, home theatre systems, set top boxes and digital TV. The WM8740 supports data input word lengths from 16 to 24-bits and sampling rates up to 192kHz. The WM8740 consists of a serial interface port, digital interpolation filter, multi-bit sigma delta modulator and stereo DAC in a small 28-pin SSOP package. The WM8740 also includes a digitally controllable mute and attenuator function on each channel. The internal digital filter has two selectable roll-off characteristics. A sharp or slow roll-off can be selected dependent on application requirements. Additionally, the internal digital filter can be by-passed and the WM8740 used with an external digital filter. The WM8740 supports two connection schemes for audio DAC control. The SPI-compatible serial control port provides access to a wide range of features including onchip mute, attenuation and phase reversal. A hardware controllable interface is also available.
WM8740
24-bit, High Performance 192kHz Stereo DAC
FEATURES
* * * * * * * * 120dB SNR (`A' weighted mono @48kHz), THD+N: -104dB @ FS 117dB SNR (`A' weighted stereo @48kHz), THD+N: -104dB @ FS Sampling frequency: 8kHz to 192kHz Selectable digital filter roll-off Optional interface to industry standard external filters Differential mono mode needing no glue logic Input data word: 16 to 24-bit Hardware or SPI compatible serial port control modes: * Hardware mode: mute, de-emphasis, audio format control * Serial mode: mute, de-emphasis, attenuation (256 steps), phase reversal Fully differential voltage outputs
*
APPLICATIONS
* * * CD, DVD audio Home theatre systems Professional audio systems
BLOCK DIAGRAM
MODE8X CSBIWO MC/DM1 MD/DM0 DIFFHW AGNDR MUTEB AVDDR ML/I2S MODE ZERO RSTB
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WM8740
CONTROL INTERFACE VMIDR
SCLK BCKIN LRCIN DIN SERIAL INTERFACE
MUTE/ ATTEN DIGITAL FILTERS
MUX
SIGMA DELTA MODULATOR
RIGHT DAC
LOW PASS FILTER
VOUTRP VOUTRN
MUX MUTE/ ATTEN
SIGMA DELTA MODULATOR
LEFT DAC
LOW PASS FILTER
VOUTLP VOUTLN
VMIDL
AVDDL.
AGND
DVDD
WOLFSON MICROELECTRONICS plc
Production Data, April 2004, Rev 4.0
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Copyright 2004 Wolfson Microelectronics plc
AGNDL
DGND
AVDD
WM8740 TABLE OF CONTENTS
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DESCRIPTION .......................................................................................................1 FEATURES.............................................................................................................1 APPLICATIONS .....................................................................................................1 BLOCK DIAGRAM .................................................................................................1 PIN CONFIGURATION...........................................................................................3 ORDERING INFORMATION ..................................................................................3 PIN DESCRIPTION ................................................................................................4 ABSOLUTE MAXIMUM RATINGS.........................................................................5 RECOMMENDED OPERATING CONDITIONS .....................................................6 ELECTRICAL CHARACTERISTICS ......................................................................6 DEVICE DESCRIPTION.........................................................................................9
SYSTEM CLOCK .......................................................................................................... 9
AUDIO DATA INTERFACE ....................................................................................9
NORMAL SAMPLE RATE ........................................................................................... 10 8 X FS INPUT SAMPLE RATE .................................................................................... 11 MODES OF OPERATION ........................................................................................... 11 HARDWARE CONTROL MODES ............................................................................... 11 SOFTWARE CONTROL INTERFACE......................................................................... 12 REGISTER MAP ......................................................................................................... 13 MUTE MODES ............................................................................................................ 17 FILTER RESPONSES ................................................................................................. 18
RECOMMENDED EXTERNAL COMPONENTS ..................................................21
RECOMMENDED EXTERNAL COMPONENTS VALUES ........................................... 21 SUGGESTED DIFFERENTIAL OUTPUT FILTER CIRCUIT........................................ 22 RECOMMENDED DUAL DIFFERENTIAL HARDWARE SETUP................................. 22
PACKAGE DIMENSIONS ....................................................................................23 IMPORTANT NOTICE ..........................................................................................24
ADDRESS: .................................................................................................................. 24
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WM8740 PIN CONFIGURATION
LRCIN DIN BCKIN MODE8X SCLK DIFFHW DGND DVDD AVDDR AGNDR VMIDR VOUTRP VOUTRN AGND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 ML/I2S MC/DM1 MD/DM0 MUTEB MODE CSBIWO RSTB ZERO AVDDL AGNDL VMIDL VOUTLP VOUTLN AVDD
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ORDERING INFORMATION
DEVICE TEMPERATURE RANGE -25 to +85C -25 to +85C PACKAGE MOISTURE SENSITIVITY LEVEL MSL 1 MSL 1 PEAK SOLDERING TEMPERATURE 240C 260C
WM8740EDS WM8740SEDS Reel Quantity: 2,000
28-pin SSOP 28-pin SSOP
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WM8740 PIN DESCRIPTION
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 NAME LRCIN DIN BCKIN MODE8X SCLK DIFFHW DGND DVDD AVDDR AGNDR VMIDR VOUTRP VOUTRN AGND AVDD VOUTLN VOUTLP VMIDL AGNDL AVDDL ZERO RSTB TYPE Digital input Digital input Digital input Digital input Digital input Digital input Supply Supply Supply Supply Analogue output Analogue output Analogue output Supply Supply Analogue output Analogue output Analogue output Supply Supply Digital output Digital input DESCRIPTION Sample rate clock input. Audio data serial input (except in 8XMODE when it is DINL). Audio data bit clock input . Internal pull-down, active high, 8 x fs mode. System clock input. Internal pull-down, active high, differential mono mode. Digital ground supply. Digital positive supply. Analogue positive supply. Analogue ground supply. Mid rail right channel. Right channel DAC output positive. Right channel DAC output negative. Analogue ground supply. Analogue positive supply. Left channel DAC output negative. Left channel DAC output positive. Mid rail left channel. Analogue ground supply. Analogue positive supply.
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Infinite zero detect - active low. Open drain type output with active pull-down. Reset input - active low. Internal pull-up.
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PIN NAME TYPE DESCRIPTION Hardware Mode 23 CSBIWO Digital input Internal pull-down Normal Mode Wordlength: Low for 16-bit data. High for 20-bit (normal) or 24-bit 2 I S data. Low for hardware mode. Differential Mode Wordlength: Low for 16-bit data. High for 20-bit (normal) or 24-bit 2 I S data. Low for left mono mode. High for right mono mode Low to soft mute. High for normal operation. 8X Mode Wordlength: Low for 20-bit data. High for 24-bit data.
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Software Mode Low for serial interface operation. High for software mode. Low to soft mute. High for normal operation. Control serial interface data signal. Control serial interface clock signal. Control serial interface load signal.
24
MODE
Digital input Internal pull-up
DINR
25
MUTEB
Digital input Internal pull-up
Low to soft mute. High for normal operation.
Low to soft mute. High for normal operation.
26
MD/DM0
Digital input Internal pull-up
De-emphasis mode select bit 0.
Low for no de-emphasis. High for 44.1kHz de-emphasis. Low for normal filter operation. High for filter slow roll-off. Audio serial format: Low - right justified. High - I2S.
LRP - LRCLK polarity select.
27
MC/DM1
Digital input Internal pull-up
De-emphasis mode select bit 1.
Unused. Leave unconnected.
28
ML/I2S
Digital input Internal pull-up
Audio serial format: Low - right justified. High - I2S.
Input data format: Low - right justified. High - left justified.
Note: Digital input pins have Schmitt trigger input buffers.
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 <30C / 85% Relative Humidity. Not normally stored in moisture barrier bag. MSL2 = out of bag storage for 1 year at <30C / 60% Relative Humidity. Supplied in moisture barrier bag. MSL3 = out of bag storage for 168 hours at <30C / 60% Relative Humidity. Supplied in moisture barrier bag. CONDITION Supply voltage Input Operating temperature range, TA Storage temperature prior to soldering Storage temperature after soldering MIN -0.3V GND -0.3V -25C -65C MAX +7.0V VDD + 0.3V +85C +150C
30C max / 85% RH max
Note: It is strongly recommended that AVDD, AVDDL and AVDDR are tied together. AGND, AGNDL and AGND right must also be tied together.
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WM8740 RECOMMENDED OPERATING CONDITIONS
PARAMETER Digital supply range Analogue supply range Ground Difference DGND to AGND Analogue supply current Digital supply current Analogue supply current Digital supply current Note: AVDD = 5V DVDD = 5V AVDD = 3.3V DVDD = 3.3V SYMBOL DVDD AVDD AGND, DGND -0.3 TEST CONDITIONS MIN -10% -10% TYP 3.3 to 5 3.3 to 5 0 0 13 19 12 12
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MAX +10% +10% +0.3
UNIT V V V V mA mA mA mA
DVDD must be equal to, or less than the AVDD supply (i.e. DVDD = AVDD = +5V; DVDD = AVDD = +3.3V; DVDD = +3.3V AVDD = +5V).
ELECTRICAL CHARACTERISTICS
Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, TA = +25 C, fs = 48kHz, SCKI = 256fs unless otherwise stated. PARAMETER DAC Circuit Specifications SNR (See Note 1) THD (full-scale) (See Note 2) THD+N (Dynamic range) (See Note 2) Filter Characteristics (Sharp Roll-off) Passband Stopband Passband ripple Stopband attenuation Delay time Filter Characteristics (Slow Roll-off) Passband Stopband Passband ripple Stopband attenuation Delay time Internal Analogue Filter Bandwidth Passband edge response Digital Logic Levels Input LOW level Input HIGH level Output LOW level Output HIGH level VIL VIH VOL VOH IOL = 2mA IOH = 2mA DVDD - 0.3V 2.0 DGND + 0.3V 0.8 V V -3dB 20kHz 195 -0.043 kHz dB f > 0.732fs -82 9/fs 0.001dB -3dB 0.274fs 0.459fs 0.001 dB dB s f > 0.5465fs -82 30/fs 0.0012 dB -3dB 0.4535fs 0.491fs 0.0012 dB dB s dB Mono fs @ 48kHz Stereo fs @ 48kHz Stereo fs @ 96kHz Mono 0dB Stereo 0dB -60dB -95 110 120 117 116 -104 -104 117 dB dB dB dB dB dB SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
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Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, SCKI = 256fs unless otherwise stated. PARAMETER Analogue Output Levels Output level differential Into 10k, full scale 0dB, (5V supply) Into 10k, full scale 0dB, (3.3V supply) Minimum resistance load To midrail or AC coupled (5V supply) To midrail or AC coupled (3.3V supply) Maximum capacitance load Output DC level Reference Levels Potential divider resistance Voltage at VMIDL/VMIDR POR (Power-On Reset) POR threshold Notes: 1. 2. 2.2 AVDD to VMIDL/VMIDR and VMIDL/VMIDR to AGND 10 AVDD/2 5V or 3.3V 2 1.32 1 600 100 AVDD/2 SYMBOL TEST CONDITIONS MIN TYP
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MAX
UNIT VRMS VRMS k pF V k
V
Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured `A' weighted over a 20Hz to 20kHz bandwidth. All performance measurements done with 20kHz low pass filter. Failure to use such a filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic specification values.
LRCIN tBCH BCKIN tBCY DIN tDS tDH tBL tBCL tLB
Figure 1 Audio Data Input Timing Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, SCKI = 256fs unless otherwise stated. PARAMETER BCKIN pulse cycle time BCKIN pulse width high BCKIN pulse width low BCKIN rising edge to LRCIN edge LRCIN rising edge to BCKIN rising edge DIN setup time DIN hold time SYMBOL tBCY tBCH tBCL tBL tLB tDS tDH TEST CONDITIONS MIN 100 40 40 20 20 20 20 TYP MAX UNIT ns ns ns ns ns ns ns PD Rev 4.0 April 2004 7 Audio Data Input Timing Information
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WM8740
tSCKIL SCKI tSCKIH tSCKY
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Figure 2 System Clock Timing Requirements Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, SCKI = 256fs unless otherwise stated. PARAMETER System Clock Timing Information System clock pulse width high System clock pulse width low System clock cycle time tSCKIH tSCKIL tSCKY 10 10 27 ns ns ns SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
tMLL ML/I2S tMCY tMCH tMCL MC/DM1 tMDS MD/DM0 tMDH LSB tMLD
tMHH
tMLS
Figure 3 Program Register Input Timing - SPI Compatible Serial Control Mode Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, SCKI = 256fs unless otherwise stated. PARAMETER MC/DM1 pulse cycle time MC/DM1 pulse width low MD/DM0 pulse width high MD/DM0 set-up time MC/DM1 hold time ML/I2S pulse width low ML/I2S pulse width high ML/I2S set-up time ML/I2S delay from MC SYMBOL tMCY tMCL tMCH tMDS tMDH tMLL tMHH tMLS tMLD TEST CONDITIONS MIN 80 32 32 10 10 10 10 10 10 TYP MAX UNIT ns ns ns ns ns ns ns ns ns Program Register Input Information
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WM8740 DEVICE DESCRIPTION
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The WM8740 is a high performance 128fs oversampling rate stereo DAC employing a novel 64 level sigma delta DAC design which provides optimised signal-to-noise performance and clock jitter tolerance. It is ideally suited to high quality audio applications such as CD, DVD-audio, home theatre receivers and professional mixing consoles. The WM8740 supports sample rates from 8ks/s to 192ks/s. The control functions of the WM8740 are either pin selected (hardware mode) or programmed via the serial interface (software mode). Control functions that are available include: data input word length and format selection (16-24 bits: I2S, left justified or right justified): de-emphasis sample rate selection (48kHz, 44.1kHz and 32kHz); differential output modes; a software or hardware mute and independently digitally controllable attenuation on both channels. The digital filtering may be bypassed entirely by selecting MODE8X. Data is then input directly to the DAC, bypassing the digital filters. Left and right channels are input separately, using the MODE pin as the right channel input. This mode allows the use of alternative digital filters, such as the Pacific Microsonics PMD100 HDCD filter. In addition to the normal stereo operating mode the WM8740 may also be used in dual differential mode with either the left or right channel (selectable) being output dual differentially. Two WM8740s can then be used in parallel to implement a stereo channel, each supporting a single channel differentially. Note that this mode uses 2 pairs of differential outputs for each channel - the benefit is SNR improved by 3dB. This mode is available in both software and hardware modes and may also be used in conjunction with MODE8X.
SYSTEM CLOCK
Sample rates from 8ks/s up to 96ks/s are available, and automatically selected, with a system clock of 256fs or 384fs. In addition a system clock of 128fs or 192fs may be used, with sample rates up to 192ks/s. With a 128fs or 192fs system clock 64x oversampling mode operation is automatically selected and the first stage of the digital filter is bypassed. WM8740 has an asynchronous monitor circuit, which in the event of removal of the master system clock, resets the digital filters and analogue circuits, muting the output. Re-application of the system clock re-starts the filters from an intitialised state. Control registers are not reset under this condition. The WM8740 is tolerant of asynchronous bit clock jitter. The internal signal processing resynchronises to the external LRCIN once the phase difference between bit clock and the system clock exceeds half an LRCIN period. During this re-synch period the interpolating filters will either miss or repeat an audio sample, minimising the audible effects of the operation. Table 1 shows the typical system clock frequency inputs for the WM8740. SAMPLING RATE (LRCIN) 32kHz 44.1kHz 48kHz 96kHz 192kHz SYSTEM CLOCK FREQUENCY (MHZ) 128fs 4.096 5.6448 6.114 12.288 24.576 192fs 6.144 8.467 9.216 18.432 36.864 256fs 8.192 11.2896 12.288 24.576 Unavailable 384fs 12.288 16.9340 18.432 36.864 Unavailable 512fs 16.384 22.5792 24.576 Unavailable Unavailable 768fs 24.576 33.8688 36.864 Unavailable Unavailable
Table 1 System Clock Frequencies Versus Sampling Rate
AUDIO DATA INTERFACE
Data may be input at a rate corresponding to the system clock having a rate of 256fs or 384fs, in which case an oversampling ratio of 128x is selected. Alternatively a rate of 128fs or 192fs may be used, in which case the first filter stage is bypassed and an oversampling ratio of 64x results. Finally, in MODE8X, data may be input at 8x the normal rate, in which case separate input pins are used to input the two stereo channels of data (unless DIFFHW mode and MODE8X are both selected, in which case only a mono channel is converted differentially). In MODE8X all filter stages are bypassed, prior to the sigma delta modulator, MODE8X is not supported at 192kHz sampling rate. Data is input MSB first in all modes.
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NORMAL SAMPLE RATE
In normal mode, the data is input serially on one pin for both left and right channels.
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Data can be "right justified" meaning that the last 16, 20 or 24 bits (depending on chosen PCM word length) that were clocked in prior to the transition on LRCIN are valid. Alternatively data can be "left justified" (20 and 24-bit PCM data only), where the bits are clocked in as the first 20 or 24 bits after a transition on LRCIN. For the three I2S modes supported (16-bit, 20-bit and 24-bit PCM data), data is clocked "left justified" except with one additional preceding clock cycle.
1/fs LEFT LRCIN (PIN 1) RIGHT
BCKIN (PIN 3)
16-BIT RIGHT JUSTIFIED DIN (PIN 2) 20-BIT RIGHT JUSTIFIED DIN (PIN 2) 24-BIT RIGHT JUSTIFIED DIN (PIN 2) 24-BIT LEFT JUSTIFIED DIN (PIN 2) 20-BIT LEFT JUSTIFIED DIN (PIN 2)
B2 B1 B0
B15
B2 B1
B0
B15
B2
B1 B0
B2
B1
B0
B19 B18 B17
B2 B1
B0
B19 B18 B17
B2
B1 B0
B2 B1
B0
B23 B22 B21 B20 B19
B2 B1
B0
B23 B22 B21 B20 B19
B2
B1 B0
B0
B23 B22 B21
B4
B3
B2 B1
B0
B23 B22 B21
B4 B3
B2 B1
B0
B0
B19 B18 B17
B0
B19 B18 B17
B0
LEFT LRCIN (PIN 1)
RIGHT
BCKIN (PIN 3)
16-BIT I 2S DIN (PIN 2)
B15
B2
B1 B0
B15
B2
B1 B0
B15
24-BIT I 2S DIN (PIN 2)
B23
B6
B5 B4 B3
B2
B1 B0
B23
B6
B5 B4
B3
B2
B1 B0
B23
20-BIT I 2S DIN (PIN 2)
B19
B2
B1 B0
B19
B2
B1 B0
B19
Figure 4 Audio Data Input Format
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8 X FS INPUT SAMPLE RATE
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Due to the higher speed of the interface in 8 x fs mode, audio data is input on two pins. The MODE pin (pin 24) is used as the second input for the right channel data and left data is input on DIN (pin2). In this mode, software control of the device is not available. The data can be input in two formats, left or right justified, selectable by ML/I2S and two word lengths (20 or 24 bit), selectable by CSBIWO. In both modes the data is always clocked in MSB first. For left justified data the word start is marked by the falling edge of LRCIN. The data is clocked in on the next 20/24 BCKIN rising edges. This format is compatible with devices such as the PMD100. For right justified the data is justified to the rising edge of LRCIN and the data is clocked in on the preceding 20/24 BCKIN rising edges before the LRCIN rising edge. This format is compatible with devices such as the DF1704 or SM5842. In both modes the polarity of LRCIN can be switched using MD/DM0. Differential hardware mode can be used in conjunction with 8fs mode by setting the DIFFHW pin high. In differential 8fs mode the data is input on DIN and output differentially. MODE is unused and must be tied low.
1/8fs LRCIN (PIN 1)
BCKIN (PIN 3)
LEFT AUDIO DATA DIN (PIN 2) RIGHT AUDIO DATA MODE (PIN 24)
B23
B22
B21
B20
B19
B2
B1
B0
B23
B22
B21
B20
B23
B22
B21
B20
B19
B2
B1
B0
B23
B22
B21
B20
1/8fs LRCIN (PIN 1)
BCKIN (PIN 3)
LEFT AUDIO DATA DIN (PIN 2) RIGHT AUDIO DATA MODE (PIN 24)
B23
B22
B21
B20
B19
B2
B1
B0
B23
B22
B21
B20
B19
B2
B1
B0
Figure 5 Audio Data Input Format (8 x fs Operation)
MODES OF OPERATION
Control of the various modes of operation is either by software control over the serial interface, or by hard-wired pin control. Selection of software or hardware mode is via MODE pin. The following functions may be controlled either via the serial control interface or by hard wiring of the appropriate pins.
HARDWARE CONTROL MODES
When the MODE pin is held `low' the following hardware modes of operation are available. In Hardware differential mode or 8X mode some of these modes/control words are altered or unavailable.
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DE-EMPHASIS CONTROL
MDDM1 PIN 27 L L H H MCDMO PIN 26 L H L H DE-EMPHASIS Off 48kHz 44.1kHz 32kHz
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Table 2 De-Emphasis Control
AUDIO INPUT FORMAT
ML/I2S PIN 28 L L H H CSBIWO PIN 23 L H L H DATA FORMAT 16 bit normal right justified 20 bit normal right justified 16 bit I2S 24 bit I2S
Table 3 Audio Input Format
SOFT MUTE
MUTEB PIN 25 L H Table 4 Soft Mute A logic low on the MUTEB pin will cause the attenuation to ramp to infinite attenuation at a rate of 128/fs seconds per 0.5dB step. Setting MUTEB high will cause the attenuation to ramp back to its previous value. FUNCTION Mute On (no output) Mute Off (normal operation)
SOFTWARE CONTROL INTERFACE
The WM8740 can be controlled using a 3-wire serial interface. MD/DM0 (pin 26) is used for the program data, MC/DM1 (pin 22) is used to clock in the program data and ML/I2S (pin 28) is use to latch in the program data. The 3-wire interface protocol is shown in Figure 6. CSB/IWO (pin 23) must be low when writing.
ML/I2S (PIN 28)
MC/DM1 (PIN 27)
MD/DM0 (PIN 26)
B15
B14
B13
B2
B1
B0
Figure 6 Three-Wire Serial Interface
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REGISTER MAP
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WM8740 controls the special functions using 4 program registers, which are 16-bits long. These registers are all loaded through input pin MD/DM0. After the 16 data bits are clocked in, ML/I2S is used to latch in the data to the appropriate register. Table 5 shows the complete mapping of the 4 registers. Note that in hardware differential mode and 8X modes, software control is not available. The hardware differential mode (Diff[1:0]) clock loss detector disable (CDD) can only be accessed by writing to M2[8:5] with the pattern 1111. Register M4 is then accessible by setting A[2:0] to 110. B15 M0 M1 M2 M3 M4 B14 B13 B12 B11 B10 B9 A0(0) A0(1) A0(0) A0(1) A0(0) B8 LDL LDR IZD B7 AL7 AR7 SF1 B6 AL6 AR6 SF0 B5 AL5 AR5 B4 AL4 AR4 IW1 REV B3 AL3 AR3 IW0 SR0 B2 AL2 AR2 OPE ATC B1 AL1 AR1 DEM LRP B0 AL0 AR0 MUT IS 2
A2 (0) A1(0) A2(0) A2(0) A2(0) A2(1) A1(0) A1(1) A1(1) A1(1)
CDD DIFF1 DIFF0
Table 5 Mapping of Program Registers REGISTER 0 1 2 BITS [7:0] 8 [7:0] 8 0 1 2 [4:3] 3 0 1 2 3 4 [7:6] 8 4 [5:4] 6 NAME AL[7:0] LDL AR[7:0] LDR MUT DEM OPE IW[1:0] I2S LRP ATC SR0 REV SF[1:0] IZD DIFF CDD DEFAULT FF 0 FF 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DESCRIPTION Attenuation data for left channel. Attenuation data load control for left channel. Attenuation data for right channel. Attenuation data load control for right channel. Left and right DACs soft mute control. De-emphasis control. Left and right DACs operation control. Input audio data bit select. Audio data format select. Polarity of LRCIN select. Attenuator control. Digital filter slow roll-off select. Output phase reverse. Sampling rate select. Infinite zero detection circuit control. Differential output mode. Clock loss detector disable.
Table 6 Register Bit Descriptions
DAC OUTPUT ATTENUATION
The level of attenuation for eight bit code X, is given by: 0.5 (X - 255) dB, 1 X 255 - dB (mute), X=0
Bit 8 in register 0 (LDL) is used to control the loading of attenuation data in B[7:0]. When LDL is set to 0, attenuation data will be loaded into AL[7:0], but it will not affect the filter attenuation. LDR in register 1 has the same function for right channel attenuation. Only when LDL or LDR is set to '1' will the filter attenuation be updated. This permits left and right channel attenuation to be updated simultaneously. Attenuation level is controlled by AL[7:0] (left channel) or AR[7:0] (right channel). Attenuation levels are given in Table 7.
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X[7:0] 00(hex) 01(hex) : : FD(hex) FE(hex) FF(hex) Table 7 Attenuation Control Level ATTENUATION LEVEL - dB (mute) -127.0dB : : -1.0dB -0.5dB 0.0dB
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Bit 2 in Reg3 is used to control the attenuator (ATC). When ATC is "high", the attenuation data loaded in program register 0 is used for both the left and the right channels. When ATC is low, the attenuation data for each register is applied separately to left and right channels.
SOFT MUTE
MUT (REG2, B0) L H Table 8 Soft Mute Setting MUT causes the attenuation to ramp from the current value down to 00. The values held in the attenuation registers are unchanged. When MUT is reset the attenuation will ramp back up to the previous value. The ramp rate is 128/fs s/0.5dB step. Soft Mute off (normal operation) Soft Mute on (no output)
DIGITAL DE-EMPHASIS
DEM (REG2, B1) L H De-emphasis off De-emphasis on
Table 9 Digital De-Emphasis
DAC OPERATION ENABLE
OPE (REG2,B2) L H Normal operation DAC output forced to bipolar zero, irrespective of input data.
Table 10 DAC Operation Enable
AUDIO DATA INPUT FORMAT
I2S (REG3, B0) 0 0 0 0 1 1 1 1 IW1 (REG2, B4) 0 0 1 1 0 0 1 1 IW0 (REG2, B3) 0 1 0 1 0 1 0 1 AUDIO INTERFACE 16-bit standard right justified 20-bit standard right justified 24-bit standard right justified 24-bit left justified (MSB first) 16-bit I2S 24-bit I S 20-bit I2S 20-bit left justified (MSB first)
2
Table 11 Audio Data Input Format
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POLARITY OF LR INPUT CLOCK
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The left channel data for a particular sample instant is always input first, then the right channel data. LRP (REG3, B1) L H LR High - left channel LR Low - right channel LR Low - left channel LR High - right channel
Table 12 Polarity of LR Input Clock
INDIVIDUAL OR COMMON ATTENUTATION CONTROL
ATC (REG3, B2) L H Individual control Common control from Reg0
Table 13 Individual or Common Attenuation Control
DIGITAL FILTER ROLL-OFF SELECTION
SRO (REG3, B3) L H Sharp Slow
Table 14 Digital Filter Roll-Off Selection
ANALOGUE OUTPUT POLARITY REVERSAL
REV (REG3, B4) L H Normal Inverted
Table 15 Analogue Output Polarity Reversal
DE-EMPHASIS SAMPLE RATE
SF1 (REG3, B7) 0 0 1 1 SF0 (REG3, B6) 0 1 0 1 SAMPLE RATE No de-emphasis 48kHz 44.1kHz 32kHz
Table 16 De-Emphasis Sample Rate
INFINITE ZERO DETECT
IZD (REG3, B8) L H Zero detect mute off Zero detect mute on
Table 17 Infinite Zero Detect
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SOFTWARE DIFFERENTIAL MONO MODE
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To control the WM8740 in software differential mode register M4 must be written to. A `key' register write must be made to register M2 to allow access to register M4 which is `locked' as default. Bits B5 to B8 of register M2 must be set to `1' (0x01e0). With register M4 `unlocked', bits B4 and B5 may be used to set the required differential output mode; normal stereo, reversed stereo, mono left or mono right, as shown in Table 18. DIFF[1:0] B[5:4]) 00 10 01 DIFFERENTIAL OUTPUT MODE Stereo Stereo reverse. Mono left - differential outputs. VOUTLP (17) is left channel. VOUTLN (16) is left channel inverted. VOUTRP (12) is left channel inverted. VOUTRN (13) is left channel. Mono right - differential outputs. VOUTLP (17) is right channel inverted. VOUTLN (16) is right channel. VOUTRP (12) is right channel. VOUTRN (13) is right channel inverted.
11
Table 18 Differential Output Modes Using these controls a pair of WM8740 devices may be used to build a dual differential stereo implementation with higher performance and differential output. Note: DIFFHW mode pin may be used to achieve the same result by hardware means.
CLOCK LOSS DETECTOR DISABLE CDD (REG4, B6)
L R Clock loss detector on Clock loss detector off
Table 19 Clock Loss Detector Disable When the system clock is inactive for approximately 100s, the clock loss detector circuit detects the loss of clock and the analogue circuitry is forced into a mute condition and the digital filters reset. Setting the CDD bit disables this behaviour.
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WM8740
MUTE MODES
The device has various mute modes. DIGITAL FILTER ANRES Reg bit OPE = `1' MUTEB pin Unaffected Gain ramped to zero On release volume ramps to previous value Automute has no effect on digital filters As MUTEB pin Gain = -dB Gain initialised to 0dB Not running (no clock). On clock restart, filters initialised, RAM initialised. Registers unchanged Filters initialised, RAM initialised. Registers unchanged Reset - gain initialised to 0dB Reset Asserted
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ANALOGUE ANMUTE Asserted Asserted when gain = 0 Asserted after 1024 zero input samples if IZD = 1 As MUTEB pin Asserted Asserted Asserted
AUTOMUTE (detect 1024 zero input samples) Reg bit MUT Gain = 00 (left and right) RAM initialise Loss of system clock No LRCLK or invalid SCLK/LRCLK ratio RB Power-on reset Table 20 Mute Modes
Asserted Asserted Asserted
Asserted Asserted Asserted
ANRES is the reset to the switched capacitor filter. 1. ANMUTE is an analogue muting signal gating the analogue signal at the output (after the SC filter) 2. AUTOMUTE is asserted when both the IZD register bit is asserted and the input audio data has been zero on both left and right channels for 1024 input samples. The first non-zero sample de-asserts. 3. Applying a logic low to MUTEB or setting MUT in Reg2 causes the gain registers to ramp to zero. When a logic high is applied, the gain ramps slowly back up to the value held in the appropriate attenuation register (AL or AR). The ramp rate = 128/fs s/0.5dB step.
If SOFTMUTE is set or MUTEB=0 then GAINL and GAINR are overridden to 00 GAINL[0:7] GAINR[0:7] Signal Processing
SOFTMUTE MUTEB
gain ramps between previous and new gain setting
Automute: Detect 1024 zero input samples
IZD
OPE FREQ_INVALID INIT
ANMUTE
ZERO
Figure 7 Mute Modes
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WM8740
FILTER RESPONSES
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Figure 8 Digital Filter Response (Sharp Roll-off Mode)
Figure 9 Digital Filter Response (Sharp Roll-off Mode)
Figure 10 Digital Filter Response (Slow Roll-off Mode)
Figure 11 Digital Filter Response (Slow Roll-off Mode)
0
-20
Response (dB)
-40
-60
-80
-100
-120 0 0.2 0.4 0.6 0.8 1 1.2 Frequency (Fs) 1.4 1.6 1.8 2
Figure 12 Digital Filter Response 128fs Mode (192kHz Sample Rate) Normal Mode - Solid, Slow Mode - Dashed
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WM8740
1 0.8
1 0.8
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Impulse Response
Impulse Response
0.6 0.4 0.2 0 -0.2 -0.4 0 10 20 30 40 Time (input samples) 50 60
0.6 0.4 0.2 0 -0.2 -0.4 0 10 20 30 40 Time (input samples) 50 60
Figure 13 Impulse Response (Normal Roll-off, no De-emphasis)
Figure 14 Impulse Response (Slow Roll-off, no De-emphasis)
0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -6.0 -7.0 -8.0 -9.0 -10.0 0 2000 4000 6000 8000 10000 12000 14000 16000 Frequency (Fs) Response (dB) Response (dB)
0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -6.0 -7.0 -8.0 -9.0 -10.0 0 5000 10000 Frequency (Fs) 15000 20000
Figure 15 De-emphasis frequency response (fs=32kHz)
Figure 16 De-emphasis frequency response (fs=44.1kHz)
0.0 -1.0 -2.0
0.4 0.3 0.2
-3.0 Response (dB) -4.0 -5.0 -6.0 -7.0 -0.2 -8.0 -9.0 -10.0 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 Frequency (Fs) -0.3 -0.4 0 2000 4000 6000 8000 Frequency (Fs) 10000 12000 14000 16000 Response (dB) 0.1 0.0 -0.1
Figure 17 De-emphasis frequency response (fs=48kHz)
Figure 18 De-emphasis frequency response error (fs=32kHz)
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WM8740
0.4 0.3 0.2 Response (dB)
Response (dB) 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4
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0.1 0.0 -0.1 -0.2 -0.3 -0.4 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 Frequency (Fs)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Frequency (Fs)
Figure 19 De-emphasis frequency response error (fs=44.1kHz)
Figure 20 De-emphasis frequency response error (fs=48kHz)
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WM8740 RECOMMENDED EXTERNAL COMPONENTS
DVDD 8 + C1 C2 7 DGND AGND AGNDR AGNDL 28 27 ML/I2S MC/DM1 MD/DM0 CSB/IWO RSTB VOUTLN VOUTLP VOUTRN VOUTRP 12 + DGND DVDD AVDD AVDDR AVDDL 15 9 20 + C3 14 10 19 16 17 13 AGND C4 C5 C6 AVDD
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LEFT OUTPUT DATA + RIGHT OUTPUT DATA
Software I/F or Hardware Control
26 23 22
12
MODE8X
WM8740
6 DIFFHW 21 24
AVDD R1
MODE
ZERO
25
MUTEB
VMIDR VMIDL
11 18 + C11 C9 C10 C12 +
1
LRCIN DIN BCKIN
Audio Serial Data I/F
R2
2 3
AGND
System Clock Input
R2
5
SCLK
Notes: 1. 2. 3.
AGND and DGND should be connected as close to the WM8740 as possible. C2 to C 5, C 9 and C11 should be positioned as close to the WM8740 as possible. Capacitor type used can have a big effect on device performance. It is recommended that capacitors with very low ESR are used and that ceramics are either NPO or COG type material to achieve best performance from the WM8740.
Figure 21 External Components Diagram
RECOMMENDED EXTERNAL COMPONENTS VALUES
COMPONENT REFERENCE C1 and C6 C2 to C5 C7 and C8 C9 and C11 C10 and C12 R1 R2 SUGGESTED VALUE 10F 0.1F 10F 0.1F 10F 10k 51 Resistor to AVDD for open drain output operation. Source termination resistors. DESCRIPTION De-coupling for DVDD and AVDD. De-coupling for DVDD and AVDD. Output AC coupling caps to remove VMID DC level from outputs. Reference de-coupling capacitors for VMIDR and VMIDL.
Table 21 External Components Description
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WM8740
SUGGESTED DIFFERENTIAL OUTPUT FILTER CIRCUIT
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Figure 22 Suggested Differential Output Filter Circuit
RECOMMENDED DUAL DIFFERENTIAL HARDWARE SETUP
Figure 23 Recommended Dual Differential Hardware Setup
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WM8740 PACKAGE DIMENSIONS
DS: 28 PIN SSOP (10.2 x 5.3 x 1.75 mm)
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DM007.D
b
28
e
15
E1
E
1
D
14
GAUGE PLANE
c A A2 A1
L
0.25
L1
-C0.10 C
SEATING PLANE
Symbols A A1 A2 b c D e E E1 L L1 REF: MIN ----0.05 1.65 0.22 0.09 9.90 7.40 5.00 0.55 0
o
Dimensions (mm) NOM --------1.75 0.30 ----10.20 0.65 BSC 7.80 5.30 0.75 0.125 REF o 4 JEDEC.95, MO-150
MAX 2.0 0.25 1.85 0.38 0.25 10.50 8.20 5.60 0.95 8
o
NOTES: A. ALL LINEAR DIMENSIONS ARE IN MILLIMETERS. B. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. C. BODY DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSION, NOT TO EXCEED 0.20MM. D. MEETS JEDEC.95 MO-150, VARIATION = AH. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS.
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WM8740
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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 26 Westfield Road Edinburgh EH11 2QB United Kingdom
Tel :: +44 (0)131 272 7000 Fax :: +44 (0)131 272 7001 Email :: sales@wolfsonmicro.com
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