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DESCRIPTION
The WM8718 is a high performance differential stereo DAC designed for audio applications such as DVD, home theatre systems and digital TV. The WM8718 supports PCM data input word lengths from 16 to 32-bits and sampling rates up to 192kHz. The WM8718 consists of a serial interface port, digital interpolation filters, multi-bit sigma delta modulators and differential stereo DAC in a small 20-pin SSOP package. The WM8718 includes a digitally controllable mute, an attenuate function and zero flag output for each channel. The 3-wire serial control port provides access to a wide range of features including on-chip mute, attenuation and phase reversal. The WM8718 is an ideal device to interface to AC-3, DTS, and MPEG audio decoders for surround sound applications, or for use in DVD players including those supporting DVD-A.
WM8718
24 Bit Differential Stereo DAC with Volume Control
FEATURES
* * * 24 bit Stereo DAC Fully Differential Voltage Outputs Audio Performance - 111dB SNR (`A' weighted @ 48kHz) DAC - -100dB THD DAC Sampling Frequency: 8kHz - 192kHz 3 Wire Serial Control Interface Programmable Audio Data Interface Modes - I2S, Left, Right Justified, DSP - 16/20/24/32 bit Word Lengths Independent Digital Volume Control on Each Channel with 127.5dB Range in 0.5dB Steps Independent Zero Flag Outputs 3.0V - 5.5V Supply Operation 20-pin SSOP Package
* * *
* * * *
APPLICATIONS
* * * CD, DVD, and DVD-Audio Players Home theatre systems Professional mixing desks
BLOCK DIAGRAM
LATCH SDIN SCLK
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WM8718
CONTROL INTERFACE
ZEROFR ZEROFL
BCKIN LRCIN DIN
AUDIO INTERFACE
ATT/ MUTE DIGITAL FILTERS ATT/ MUTE
SIGMA DELTA MODULATOR
VOUTRP DAC VOUTRN VOUTLP DAC VOUTLN
SIGMA DELTA MODULATOR
VMID
MCLK
VREFP
WOLFSON MICROELECTRONICS plc www.wolfsonmicro.com
Copyright 2004 Wolfson Microelectronics plc
VREFN
DVDD
DGND
AVDD
AGND
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WM8718 TABLE OF CONTENTS
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DESCRIPTION ............................................................................................................1 FEATURES..................................................................................................................1 APPLICATIONS ..........................................................................................................1 BLOCK DIAGRAM ......................................................................................................1 TABLE OF CONTENTS ..............................................................................................2 PIN CONFIGURATION................................................................................................3 ORDERING INFORMATION .......................................................................................3 PIN DESCRIPTION .....................................................................................................4 ABSOLUTE MAXIMUM RATINGS..............................................................................5 DC ELECTRICAL CHARACTERISTICS .....................................................................6 ELECTRICAL CHARACTERISTICS ...........................................................................6
TERMINOLOGY ................................................................................................................. 7 MASTER CLOCK TIMING .................................................................................................. 8 DIGITAL AUDIO INTERFACE TIMINGS ............................................................................ 8 3-WIRE SERIAL CONTROL INTERFACE TIMING ............................................................ 9
DEVICE DESCRIPTION............................................................................................10
INTRODUCTION ...............................................................................................................10 CLOCKING SCHEMES .....................................................................................................10 DIGITAL AUDIO INTERFACE ...........................................................................................10 AUDIO DATA SAMPLING RATES.....................................................................................12 REGISTER MAP ...............................................................................................................14 DIGITAL FILTER CHARACTERISTICS.............................................................................21 DAC FILTER RESPONSES...............................................................................................21
DIGITAL DE-EMPHASIS CHARACTERISTICS ........................................................22 TYPICAL PERFORMANCE.......................................................................................23 APPLICATIONS INFORMATION ..............................................................................24
RECOMMENDED EXTERNAL COMPONENTS ................................................................24 RECOMMENDED EXTERNAL COMPONENTS VALUES .................................................24
RECOMMENDED ANALOGUE LOW PASS FILTER FOR PCM DATA FORMAT (OPTIONAL) ..............................................................................................................25 PACKAGE DIMENSIONS .........................................................................................26 IMPORTANT NOTICE ...............................................................................................27
ADDRESS: ........................................................................................................................27
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WM8718 PIN CONFIGURATION
LRCIN DVDD DGND AVDD VREFP VREFN AGND VMID VOUTRP VOUTRN 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16
DIN
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BCKIN MCLK
ZEROFL
ZEROFR
WM8718
15 14 13 12 11
SCLK SDIN
LATCH
VOUTLP
VOUTLN
ORDERING INFORMATION
DEVICE WM8718EDS WM8718EDS/R WM8718SEDS WM8718SEDS/R Note: Reel quantity = 2,000 TEMP. RANGE -25 to +85oC -25 to +85oC -25 to +85oC -25 to +85oC PACKAGE 20-pin SSOP 20-pin SSOP (tape and reel) 20-pin SSOP (lead free) 20-pin SSOP (lead free, tape and reel) MOISTURE SENSITIVITY LEVEL MSL1 MSL1 MSL1 MSL1 PEAK SOLDERING TEMP 240C 240C 260C 260C
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WM8718 PIN DESCRIPTION
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 NAME LRCIN DVDD DGND AVDD VREFP VREFN AGND VMID VOUTRP VOUTRN VOUTLN VOUTLP LATCH SDIN SCLK ZEROFR ZEROFL MCLK BCLKIN DIN TYPE Digital Input Supply Supply Supply Supply Supply Supply Analogue Output Analogue Output Analogue Output Analogue Output Analogue Output Digital Input P.U. Digital Input Digital Input P.D. Positive Digital Supply Ground Digital Supply Positive Analogue Supply Positive DAC reference Supply Negative DAC reference Supply Ground Analogue Supply Mid Rail Decoupling Point Right Channel DAC Output Positive Right Channel DAC Output Negative Left Channel DAC Output Negative Left Channel DAC Output Positive Serial Control Load Input Serial Control Data Input Serial Control Data Input Clock DESCRIPTION PCM DAC Sample Rate Clock Input
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Digital Output (Open drain) P.D. Infinite ZERO Detect Flag for Right Channel Digital Output (Open drain) P.D. Infinite ZERO Detect Flag for Left Channel Digital Input Digital Input Digital Input Master Clock Input PCM Audio Data Bit Clock Input PCM Serial Audio Data Input
Note: Digital input pins have Schmitt trigger input buffers. Pins marked P.U. or P.D. have an internal pull-up or pull-down resistor.
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WM8718 ABSOLUTE MAXIMUM RATINGS
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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. The Moisture Sensitivity Level for each package type is specified in Ordering Information. CONDITION Digital supply voltage (DVDD) Analogue supply voltage (AVDD) Voltage range digital inputs Master Clock Frequency Operating temperature range, TA Storage temperature after soldering -25C -65C MIN -0.3V -0.3V DGND -0.3V MAX +7V +7V VDD +0.3V 37MHz +85C +150C
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WM8718 DC ELECTRICAL CHARACTERISTICS
PARAMETER Digital supply range Analogue supply range Ground Difference DGND to AGND Supply current Supply current AVDD = 3.3V AVDD = 5V DVDD = 3.3V DVDD = 5V SYMBOL DVDD AVDD AGND, DGND -0.3 0.191a 0.191a 160 uA 160 uA TEST CONDITIONS MIN 3.0 3.0 0 0 19 22 7.1 8.3 +0.3 TYP MAX 5.5 5.5
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UNIT V V V V mA mA mA mA
Notes: 1. This value represents the current usage when there are no switching digital inputs, MCLK is applied and the chip is in power down mode 2. Digital supply DVDD must never be more than 0.3V greater than AVDD.
ELECTRICAL CHARACTERISTICS
Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER Digital Logic Levels (TTL Levels) Input LOW level Input HIGH level Output LOW Output HIGH Analogue Reference Levels Reference voltage Potential divider resistance DAC Output (Load = 10k 50pF) 0dBFs Full scale output voltage SNR (Note 1,2,3) SNR (Note 1,2,3) SNR (Note 1,2,3) SNR (Note 1,2,3) At DAC outputs A-weighted, @ fs = 48kHz A-weighted @ fs = 96kHz A-weighted @ fs = 192kHz A-weighted, @ fs = 48kHz AVDD = 3.3V A-weighted @ fs = 96kHz AVDD = 3.3V Non `A' weighted @ fs = 48kHz 1kHz, 0dBFs 1kHz, -60dBFs 105 2x AVDD/5 111 109 109 105 Vrms dB dB dB dB RVMID VMID AVDD/2 50mV AVDD/2 8.7k AVDD/2 + 50mV V VIL VIH VOL VOH IOL = 1mA IOH = 1mA DVDD - 0.3V 2.0 AGND + 0.3V 0.8 V V V V SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
SNR (Note 1,2,3)
102
dB
SNR (Note 1,2,3) THD (Note 1,2,3) THD+N (Dynamic range, Note 2) DAC channel separation
108 -100 105 111 100 -80
dB dB dB dB
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WM8718
Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER Analogue Output Levels Differential Output level Load = 10k, 0dBFS Load = 10k, 0dBFS, (AVDD = 3.3V) 2.0 1.32 1 To midrail or a.c. coupled To midrail or a.c. coupled (AVDD = 3.3V) 5V or 3.3V 1 600 SYMBOL TEST CONDITIONS MIN TYP MAX
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UNIT VRMS VRMS %FSR k
Gain mismatch channel-to-channel Minimum resistance load
Maximum capacitance load Output d.c. level Power On Reset (POR) POR threshold
100 (AVDDGND)/2 2.0
pF V
V
Notes: 1. Ratio of output level with 1kHz full scale input, to the output level with all ZEROS into the digital input, over a 20Hz to 20kHz bandwidth. 2. All performance measurements done with 20kHz low pass filter, and where noted an A-weight 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. 3. VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).
TERMINOLOGY
1. 2. Signal-to-noise ratio (dB) - SNR is a measure of the difference in level between the full-scale output and the output with a ZERO signal applied. (No Auto-ZERO or Automute function is employed in achieving these results). Dynamic range (dB) - DNR is a measure of the difference between the highest and lowest portions of a signal. Normally a THD+N measurement at 60dB below full scale. The measured signal is then corrected by adding the 60dB to it. (e.g. THD+N @ -60dB= -32dB, DR= 92dB). THD+N (dB) - THD+N is a ratio, of the rms values, of (Noise + Distortion)/Signal. Stop band attenuation (dB) - Is the degree to which the frequency spectrum is attenuated (outside audio band). Channel Separation (dB) - Also known as Cross Talk. This is a measure of the amount one channel is isolated from the other. Normally measured by sending a full-scale signal down one channel and measuring the other. Pass-Band Ripple - Any variation of the frequency response in the pass-band region.
3. 4. 5. 6.
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WM8718
MASTER CLOCK TIMING
tMCLKL MCLK tMCLKH tMCLKY
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Figure 1 Master Clock Timing Requirements
Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER Master Clock Timing Information MCLK Master clock pulse width high MCLK Master clock pulse width low MCLK Master clock cycle time MCLK Duty cycle tMCLKH tMCLKL tMCLKY 13 13 26 40:60 60:40 ns ns ns SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
DIGITAL AUDIO INTERFACE TIMINGS
tBCH BCKIN tBCY tBCL
LRCIN tDS DIN tDH tLRH tLRSU
Figure 2 Digital Audio Data Timing
Test Conditions o AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25 C, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER BCKIN cycle time BCKIN pulse width high BCKIN pulse width low LRCIN set-up time to BCKIN rising edge LRCIN hold time from BCKIN rising edge DIN set-up time to BCKIN rising edge DIN hold time from BCKIN rising edge SYMBOL tBCY tBCH tBCL tLRSU tLRH tDS tDH TEST CONDITIONS MIN 40 16 16 8 8 8 8 TYP MAX UNIT ns ns ns ns ns ns ns
Audio Data Input Timing Information
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3-WIRE SERIAL CONTROL INTERFACE TIMING
tCSL LATCH tSCY tSCH SCLK tSCL tSCS tCSS tCSH
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SDIN tDSU tDHO
LSB
Figure 3 Program Register Input Timing - 3-Wire Serial Control Mode
Test Conditions AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SCLK rising edge to LATCH rising edge SCLK pulse cycle time SCLK pulse width low SCLK pulse width high SDIN to SCLK set-up time SCLK to SDIN hold time LATCH pulse width low LATCH pulse width high LATCH rising to SCLK rising SYMBOL tSCS tSCY tSCL tSCH tDSU tDHO tCSL tCSH tCSS TEST CONDITIONS MIN 40 80 20 20 20 20 20 20 20 TYP MAX UNIT ns ns ns ns ns ns ns ns ns
Program Register Input Information
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WM8718 DEVICE DESCRIPTION
INTRODUCTION
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The WM8718 is a high performance DAC designed for digital consumer audio applications. Its range of features makes it ideally suited for use in DVD players, AV receivers and other high-end consumer audio equipment. WM8718 is a complete 2-channel differential stereo audio digital-to-analogue converter, including digital interpolation filter, multi-bit sigma delta with dither, switched capacitor multi-bit stereo DAC. The WM8718 includes an on-chip digital volume control, configurable digital audio interface and a 3 wire MPU control interface. The WM8718 has left and right zero flag output pins, allowing the user to control external muting circuits. It is fully compatible and an ideal partner for a range of industry standard microprocessors, controllers and DSPs. The software control interface may be asynchronous to the audio data interface. The control data will be re-synchronised to the audio processing internally. Operation using a master clock of 256fs, 384fs, 512fs or 768fs is provided, selection between clock rates being automatically controlled. Sample rates (fs) from less than 8kHz to 192kHz are allowed, provided the appropriate master clock is input. The audio data interface supports right justified, left justified and I2S (Philips left justified, one bit delayed) interface formats along with a highly flexible DSP serial port interface. The device is packaged in a small 20-pin SSOP.
CLOCKING SCHEMES
In a typical digital audio system there is one central clock source producing a reference clock to which all audio data processing is synchronised. This clock is often referred to as the audio system's Master Clock. The external master system clock can be applied directly through the MCLK input pin with no software configuration necessary for sample rate selection. Note that on the WM8718, MCLK is used to derive clocks for the DAC path. The DAC path consists of DAC sampling clock, DAC digital filter clock and DAC digital audio interface timing. In a system where there are a number of possible sources for the reference clock, it is recommended that the clock source with the lowest jitter be used to optimise the performance of the DAC.
DIGITAL AUDIO INTERFACE
Audio data is applied to the internal DAC filters via the Digital Audio Interface. Five popular interface formats are supported: * * * * * Left Justified mode Right Justified mode I2S mode DSP Early mode DSP Late mode
All five formats send the MSB first and support word lengths of 16, 20, 24 and 32 bits with the exception that 32 bit data is not supported in right justified mode. DIN and LRCIN maybe configured to be sampled on the rising or falling edge of BCKIN. In left justified, right justified and I2S modes, the digital audio interface receives data on the DIN input. Audio Data is time multiplexed with LRCIN indicating whether the left or right channel is present. LRCIN is also used as a timing reference to indicate the beginning or end of the data words. The minimum number of BCKINs per LRCIN period is 2 times the selected word length. LRCIN must be high for a minimum of word length BCKINs and low for a minimum of word length BCKINs. Any mark to space ratio on LRCIN is acceptable provided the above requirements are met
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WM8718
Production Data The WM8718 will automatically detect when data with a LRCIN period of exactly 32 BCKINs is sent, and select 16-bit mode - overriding any previously programmed word length. Word length will revert to a programmed value only if a LRCIN period other than 32 BCKINs is detected. In DSP early or DSP late mode, the data is time multiplexed onto DIN. LRCIN is used as a frame sync signal to identify the MSB of the first word. The minimum number of BCKINs per LRCIN period is 2 times the selected word length. Any mark to space ratio is acceptable on LRCIN provided the rising edge is correctly positioned. (See Figure 7 and Figure 8)
LEFT JUSTIFIED MODE
In left justified mode, the MSB is sampled on the first rising edge of BCKIN following a LRCIN transition. LRCIN is high during the left data word and low during the right data word.
1/fs
LEFT CHANNEL LRCIN
RIGHT CHANNEL
BCKIN
DIN
1
2
3
n-2 n-1
n
1
2
3
n-2 n-1
n
MSB
LSB
MSB
LSB
Figure 4 Left Justified Mode Timing Diagram
RIGHT JUSTIFIED MODE
In right justified mode, the LSB is sampled on the rising edge of BCKIN preceding a LRCIN transition. LRCIN is high during the left data word and low during the right data word.
1/fs
LEFT CHANNEL LRCIN
RIGHT CHANNEL
BCKIN
DIN
1
2
3
n-2 n-1
n
1
2
3
n-2 n-1
n
MSB
LSB
MSB
LSB
Figure 5 Right Justified Mode Timing Diagram
I S MODE
In I2S mode, the MSB is sampled on the second rising edge of BCKIN following a LRCIN transition. LRCIN is low during the left data word and high during the right data word.
2
1/fs
LEFT CHANNEL LRCIN
RIGHT CHANNEL
BCKIN
1 BCKIN 1 BCKIN 3 n-2 n-1 n 1 2 3 n-2 n-1 n
DIN
1
2
MSB
LSB
MSB
LSB
Figure 6 I2S Mode Timing Diagram
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WM8718
DSP EARLY MODE
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In DSP early mode, the first bit is sampled on the BCKIN rising edge following the one that detects a low to high transition on LRCIN. No BCKIN edges are allowed between the data words. The word order is DIN left, DIN right.
1 BCKIN 1/fs 1 BCKIN
LRCIN
BCKIN
LEFT CHANNEL
RIGHT CHANNEL
NO VALID DATA
DIN
1
2
n-1
n
1
2
n-1
n
MSB
LSB
Input Word Length (IWL)
Figure 7 DSP Early Mode Timing Diagram
DSP LATE MODE
In DSP late mode, the first bit is sampled on the BCKIN rising edge, which detects a low to high transition on LRCIN. No BCKIN edges are allowed between the data words. The word order is DIN left, DIN right.
1/fs
LRCIN
BCKIN
LEFT CHANNEL
RIGHT CHANNEL
NO VALID DATA
DIN
1
2
n-1
n
1
2
n-1
n
1
MSB
LSB
Input Word Length (IWL)
Figure 8 DSP Late Mode Timing Diagram
AUDIO DATA SAMPLING RATES
The master clock for WM8718 can range from 128fs to 768fs where fs is the audio sampling frequency (LRCIN), typically 32kHz, 44.1kHz, 48kHz, 96kHz or 192kHz. The master clock is used to operate the digital filters and the noise shaping circuits. The WM8718 has a master clock detection circuit that automatically determines the relationship between the master clock frequency and the sampling rate (to within +/- 32 system clocks). If there is greater than 32 clocks error, the system will default to 768fs. The master clock should be synchronised with LRCIN, although the WM8718 is tolerant of phase differences or jitter on this clock. See Table 1.
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WM8718
SAMPLING RATE (LRCIN) 32kHz 44.1kHz 48kHz 96kHz 192kHz MASTER CLOCK FREQUENCY (MHZ) (MCLK) 128fs 4.096 5.6448 6.144 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
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768fs 24.576 33.8688 36.864 Unavailable Unavailable
16.384 22.5792 24.576 Unavailable Unavailable
Table 1 Typical Relationships Between Master Clock Frequency and Sampling Rate
SOFTWARE CONTROL INTERFACE
The software control interface may be operated using a 3-wire (SPI-compatible) interface. In this mode, SDIN is used for the program data, SCLK is used to clock in the program data and LATCH is used to latch in the program data. The 3-wire interface protocol is shown in Figure 9.
LATCH SCLK
SDIN
A6
A5
A4
A3
A2
A1
A0
D8
D7
D6
D5
D4
D3
D2
D1
D0
Figure 9 3-Wire Serial Control Interface Notes: 1. A[6:0] are Control Address Bits 2. D[8:0] are Control Data Bits
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REGISTER MAP
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WM8718 uses a total of 4 program registers, which are 16-bits long. These registers are all loaded through input pin SDIN, using the 3-wire serial control mode as shown in 9. A6 M0 M1 M2 M3
0 0 0 0
A5
0 0 0 0
A4
0 0 0 0
A3
0 0 0 0
A2
0 0 0 0
A1
0 0 1 1
A0
0 1 0 1
D8
UPDATEL UPDATER
D7
LAT7 RAT7
D6
LAT6 RAT6 0
1
D5
LAT5 RAT5 0
1
D4
LAT4 RAT4 0
1
D3
LAT3 RAT3 0
1
D2
LAT2 RAT2
D1
LAT1 RAT1
D0
LAT0 RAT0 MUT IWL[0]
ZCDINIT ZEROFLR 0
1
PWDN DEEMPH FMT[0] IWL[1]
REV
BCP
ATC
LRP
FMT[1]
ADDRESS Table 2 Mapping of Program Registers
DATA
Note: 1. These register bits must be written as 0 otherwise device function can not be guaranteed. REGISTER ADDRESS (A3,A2,A1,A0) 0000 DACL Attenuation 0001 DACR Attenuation 0010 Mode Control BITS NAME DEFAULT DESCRIPTION
[7:0] 8
LAT[7:0] UPDATEL
11111111 (0dB) Attenuation data for left channel in 0.5dB steps, see Table 5 0 Attenuation data load control for left channel. 0: Store DACL in intermediate latch (no change to output) 1: Store DACL and update attenuation on both channels. Attenuation data load control for right channel. 0: Store DACR in intermediate latch (no change to output) 1: Store DACR and update attenuation on both channels. Left and Right DACs Soft Mute Control. 0: No mute 1: Mute De-emphasis Control. 0: De-emphasis off 1: De-emphasis on Left and Right DACs Power-down Control 0: All DACs running, output is active 1: All DACs in power saving mode, output muted Zero Flag Pin Control. 0: Channel independent 1: AND of both channels on ZEROFL output pin Zero Cross Detect Control. 0: Zero cross detect enabled 1: Zero cross detect disabled Input Word Length. 00: 16-bit mode 01: 20-bit mode 10: 24-bit mode 11: 32-bit mode(not supported in right justified mode)
[7:0] 8
RAT[7:0] UPDATER
11111111 (0dB) Attenuation data for right channel in 0.5dB steps, see Table 5 0
0
MUT
0
1
DEEMPH
0
2
PWDN
0
7
ZEROFLR
0
8
ZCDINIT
0
0011 Format Control
[1:0]
IWL[1:0]
10
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REGISTER ADDRESS (A3,A2,A1,A0) BITS NAME DEFAULT DESCRIPTION
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[3:2]
FMT[1:0]
10
Audio Data Format Select. 00: right justified mode 01: left justified mode 10: I2S mode 11: DSP mode Polarity Select for LRCIN/DSP Mode Select. 0: normal LRCIN polarity/DSP late mode 1: inverted LRCIN polarity/DSP early mode Attenuator Control. 0: All DACs use attenuation as programmed. 1: Right channel DACs use corresponding left DAC attenuation BCKIN Polarity 0: normal polarity 1: inverted polarity Output Phase Reversal, see Table 10
4
LRP
0
5
ATC
0
6
BCP
0
7
REV
0
Table 3 Register Bit Descriptions
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ATTENUATION CONTROL
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Each DAC channel can be attenuated digitally before being applied to the digital filter. Attenuation is 0dB by default but can be set between 0 and 127.5dB in 0.5dB steps using the 8 Attenuation control bits. All attenuation registers are double latched allowing new values to be pre-latched to both channels before being updated synchronously. Setting the UPDATE bit on any attenuation write will cause all pre-latched values to be immediately applied to the DAC channels.
REGISTER ADDRESS 0000 Attenuation DACL
BITS [7:0]
LABEL LAT[7:0]
DEFAULT 11111111 (0dB)
DESCRIPTION Attenuation data for Left Channel DACL in 0.5dB steps.
8
UPDATEL
0
Controls simultaneous update of all Attenuation Latches 0: Store DACL in intermediate latch (no change to output) 1: Store DACL and update attenuation on all channels. Attenuation data for Right channel DACR in 0.5dB steps.
0001 Attenuation DACR
[7:0]
RAT[7:0]
11111111 (0dB)
8
UPDATER
0
Controls simultaneous update of all Attenuation Latches 0: Store DACR in intermediate latch (no change to output) 1: Store DACR and update attenuation on all channels.
Table 4 Attenuation Register Map Note: 1. The UPDATE bit is not latched. If UPDATE=0, the Attenuation value will be written to the pre-latch but not applied to the relevant DAC. If UPDATE=1, all pre-latched values and the current value being written will be applied on the next input sample. Care should be used in reducing the attenuation as rapid large volume changes can introduce zipper noise if the ZCDINIT register bit has been set, (disabled).
2.
DAC OUTPUT ATTENUATION
Registers DACR and DACL control the left and right channel attenuation. Table 9 shows how the attenuation levels are selected from the 8-bit words. DACX[7:0] 00(hex) 01(hex) : : : FE(hex) FF(hex) Table 5 Attenuation Control Levels ATTENUATION LEVEL dB (mute) 127.5dB : : : 0.5dB 0dB
MUTE MODES
Figure 10 shows the application and release of MUTE whilst a full amplitude sinusoid is being played at 48kHz sampling rate. When MUTE (lower trace) is asserted, the output (upper trace) begins to decay exponentially from the DC level of the last input sample. The output will decay towards VMID with a time constant of approximately 64 input samples. When MUTE is deasserted, the output will restart almost immediately from the current input sample.
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1.5 1 0.5 0 -0.5 -1 -1.5 -2 -2.5 0 0.001 0.002 0.003 Time(s) 0.004 0.005
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0.006
Figure 10 Application and Release of Soft Mute
Setting the MUT register bit will apply a 'soft' mute to the input of the digital filters: REGISTER ADDRESS 0010 Mode Control BIT 0 LABEL MUT DEFAULT 0 DESCRIPTION Soft Mute select 0: Normal Operation 1: Soft mute both channels
DE-EMPHASIS MODE
Setting the DEEMPH register bit puts the digital filters into de-emphasis mode: REGISTER ADDRESS 0010 Mode Control BIT 1 LABEL DEEMPH DEFAULT 0 DESCRIPTION De-emphasis mode select: 0: De-emphasis Off 1: De-emphasis On
POWERDOWN MODE
Setting the PWDN register bit immediately connects all outputs to VMID and selects a low power mode. All trace of the previous input samples is removed, but all control register settings are preserved. When PWDN is cleared again the first 16 input samples will be ignored, as the FIR will repeat it's power-on initialisation sequence. REGISTER ADDRESS 0010 Mode Control BIT 2 LABEL PWDN DEFAULT 0 DESCRIPTION Power Down Mode Select: 0: Normal Mode 1: Power Down Mode
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ZERO FLAG OUTPUTS
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The WM8718 has two zero flag outputs pins. The WM8718 asserts a low on the corresponding zero flag pin when a sequence of more than 1024 mid-rail signal is input to the chip. The user can use the zero flag pins to control external muting circuits if required. To simplify external circuitry there is an option to have both zero flag output's ANDed internally and output on both pins. REGISTER ADDRESS 0010 Mode Control BIT 7 LABEL ZEROFLR DEFAULT 0 DESCRIPTION ZERO Flag Outputs: 0: Both pins enabled. 1: AND of both channels to both pins.
ZERO CROSS DETECT
When the WM8718 receives updates to the volume levels it will, by default, wait for the signal to pass through mid-rail for each channel before applying the update for that particular channel. This ensures that there is minimum distortion seen on the output when the volume is changed. REGISTER ADDRESS 0010 Mode Control BIT 8 LABEL ZCDINIT DEFAULT 0 DESCRIPTION Zero Cross Detect Control: 0: Enabled 1: Disabled
SELECTION OF LRCIN POLARITY
In left justified, right justified or I2S modes, the LRP register bit controls the polarity of LRCIN. If this bit is set high, the expected polarity of LRCIN will be the opposite of that shown in Figure 4, Figure 5 and Figure 6. Note that if this feature is used as a means of swapping the left and right channels, a 1 sample phase difference will be introduced. REGISTER ADDRESS 0011 Format Control BIT 4 LABEL LRP DEFAULT 0 DESCRIPTION LRCIN Polarity (normal) 0: normal LRCIN polarity 1: inverted LRCIN polarity
Table 6 LRCIN Polarity Control In DSP modes, the LRCIN register bit is used to select between early and late modes (see Figure 7 and Figure 8. REGISTER ADDRESS 0011 Format Control BIT 4 LABEL LRP DEFAULT 0 DESCRIPTION DSP Format (DSP modes) 0: Late DSP mode 1: Early DSP mode
Table 7 DSP Format Control In DSP early mode, the first bit is sampled on the BCKIN rising edge following the one that detects a low to high transition on LRCIN. In DSP late mode, the first bit is sampled on the BCKIN rising edge, which detects a low to high transition on LRCIN. No BCKIN edges are allowed between the data words. The word order is DIN left, DIN right.
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WM8718
ATTENUATOR CONTROL MODE
Production Data
Setting the ATC register bit causes the left channel attenuation settings to be applied to both left and right channel DACs from the next audio input sample. No update to the attenuation registers is required for ATC to take effect. (The right channels registry settings are preserved.) REGISTER ADDRESS 0011 PCM Control BIT 5 LABEL ATC DEFAULT 0 DESCRIPTION Attenuator Control Mode: 0: Right channels use Right attenuation 1: Right Channels use Left Attenuation
Table 8 Attenuation Control Select
BCKIN POLARITY
By default, LRCIN and DIN are sampled on the rising edge of BCKIN and should ideally change on the falling edge. Data sources which change LRCIN and DIN on the rising edge of BCKIN can be supported by setting the BCP register bit. Setting BCP to 1 inverts the polarity of BCKIN to the inverse of that shown in Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8 REGISTER ADDRESS 0011 PCM Control BIT 6 LABEL BCP DEFAULT 0 DESCRIPTION BCKIN 0: normal polarity 1: inverted polarity
Table 9 BCKIN Polarity Control
OUTPUT PHASE REVERSAL
The REV register bit controls the phase of the output signal. Setting the REV bit causes the phase of the output signal to be inverted. REGISTER ADDRESS 0011 PCM Control BIT 7 LABEL REV DEFAULT 0 DESCRIPTION Analogue Output Phase 0: Normal 1: Inverted
Table 10 Output Phase Control
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WM8718
DIGITAL AUDIO INTERFACE CONTROL REGISTERS
Production Data
The WM8718 has a fully featured PCM digital audio interface whose interface format is selected via the FMT [1:0] and IWL[1:0] register bits in register M3. REGISTER ADDRESS 0010 Format Control 0010 Format Control BIT 1:0 3:2 LABEL IWL[1:0] FMT[1:0] DEFAULT 00 00 DESCRIPTION Interface format Select Interface format Select
Table 11 Interface Format Controls
FMT[1] 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
FMT[0] 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
IWL[1] 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
IWL[0] 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
AUDIO INTERFACE DESCRIPTION (NOTE 1) 16 bit right justified mode 20 bit right justified mode 24 bit right justified mode Not available 16 bit left justified mode 20 bit left justified mode 24 bit left justified mode 32 bit left justified mode 16 bit I2S mode 20 bit I2S mode 24 bit I2S mode 32 bit I2S mode 16 bit DSP mode 20 bit DSP mode 24 bit DSP mode 32 bit DSP mode
Table 12 Audio Data Input Format Note: 1. In all modes, the data is signed 2's complement. The digital filters always input 24-bit data. If the DAC is programmed to receive 16 or 20 bit data, the WM8718 pads the unused LSBs with ZEROS. If the DAC is programmed into 32-bit mode, the 8 LSBs are treated as zero.
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WM8718
DIGITAL FILTER CHARACTERISTICS
PARAMETER Passband Edge Passband Ripple Stopband Attenuation Table 13 Digital Filter Characteristics SYMBOL TEST CONDITIONS -3dB f < 0.444fs f > 0.555fs -60 MIN TYP 0.487fs 0.05 MAX
Production Data
UNIT dB dB
DAC FILTER RESPONSES
0.2 0 0.15 -20 0.1
Response (dB)
Response (dB)
-40
0.05 0 -0.05 -0.1
-60
-80
-100
-0.15 -0.2 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 0 0.05 0.1 0.15 0.2 0.25 0.3 Frequency (Fs) 0.35 0.4 0.45 0.5
-120
Figure 11 DAC Digital Filter Frequency Response -44.1, 48 and 96kHz
Figure 12 DAC Digital Filter Ripple -44.1, 48 and 96kHz
0.2
0 0 -20
Response (dB)
-0.2
Response (dB)
-40
-0.4
-60
-0.6
-0.8 -80 -1 0 0.2 0.4 0.6 Frequency (Fs) 0.8 1 0 0.05 0.1 0.15 0.2 0.25 0.3 Frequency (Fs) 0.35 0.4 0.45 0.5
Figure 13 DAC Digital Filter Frequency Response -192kHz
Figure 14 DAC Digital Filter Ripple -192kHz
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WM8718 DIGITAL DE-EMPHASIS CHARACTERISTICS
0 1 0.5 -2 0
Response (dB)
Production Data
-4
Response (dB)
-0.5 -1 -1.5 -2
-6
-8 -2.5 -10 0 2 4 6 8 10 Frequency (kHz) 12 14 16 -3 0 2 4 6 8 10 Frequency (kHz) 12 14 16
Figure 15 De-Emphasis Frequency Response (32kHz)
0
Figure 16 De-Emphasis Error (32kHz)
0.4 0.3
-2 0.2
Response (dB)
-4
Response (dB)
0.1 0 -0.1 -0.2
-6
-8 -0.3 -10 0 5 10 Frequency (kHz) 15 20 -0.4 0 5 10 Frequency (kHz) 15 20
Figure 17 De-Emphasis Frequency Response (44.1kHz)
0
Figure 18 De-Emphasis Error (44.1kHz)
1 0.8
-2
0.6 0.4
Response (dB)
-4
Response (dB)
0.2 0 -0.2 -0.4
-6
-8
-0.6 -0.8
-10 0 5 10 15 Frequency (kHz) 20
-1 0 5 10 15 Frequency (kHz) 20
Figure 19 De-Emphasis Frequency Response (48kHz)
Figure 20 De-Emphasis Error (48kHz)
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WM8718 TYPICAL PERFORMANCE
-86 -88 -90 -92 -94 -96 -98 d B r A -106 -108 -110 -112 -114 -116 -118 -120 -160 -150 -140 -130 -120 -110 -100 -90 -80 dBV -70 -60 -50 -40 -30 -20 -100 -102 -104
Production Data
-10
+0
Figure 21 THD+N versus Input Amplitude (@ 1kHz, 'A' weighted)
+0 -10 -20 -30 -40 d B r A -50 -60 -70 -80 -90 -100 -110 -120 30 50 100 200 500 Hz 1k 2k 5k 10k 20k
Figure 22 THD+N versus Frequency ('A' weighted)
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WM8718 APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
Production Data
Figure 23 External Components Diagram
RECOMMENDED EXTERNAL COMPONENTS VALUES
COMPONENT REFERENCE C4 and C7 C1 and C6 C5 C2 C3 C8 R1 SUGGESTED VALUE 10F 0.1F 0.1uF 0.1F 10F 10F 330 DESCRIPTION De-coupling for DVDD and AVDD De-coupling for DVDD and AVDD De-coupling for VREFP positive DAC reference supply Reference de-coupling capacitors for VMID pin. Filtering for VREFP. Omit if AVDD low noise. Filtering for VREP. Use 0 if AVDD low noise.
Table 14 External Components Description
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WM8718 Production Data RECOMMENDED ANALOGUE LOW PASS FILTER FOR PCM DATA FORMAT (OPTIONAL)
R1 2K7 R2 2K7 C2 Left C1 680pF LOUTP WM8718 ROUTN R6 2K7 Right other channel R4 2K7 R3 3K R5 3K OP + C4 220pF
LOUTN
C3
680pF 220pF
ROUTP
Figure 24 Recommended Low Pass Filter (Optional)
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WM8718 PACKAGE DIMENSIONS
DS: 20 PIN SSOP (7.2 x 5.3 x 1.75 mm)
Production Data
DM0015.B
b
20
e
11
E1
E
1
10
GAUGE PLANE
D
A A2
A1 -C0.10 C
SEATING PLANE
c
L L1
0.25
Symbols A A1 A2 b c D e E E1 L L1 REF: MIN ----0.05 1.65 0.22 0.09 6.90 7.40 5.00 0.55 0
o
Dimensions (mm) NOM --------1.75 0.30 ----7.20 0.65 BSC 7.80 5.30 0.75 0.125 REF o 4 JEDEC.95, MO -150
MAX 2.0 ----1.85 0.38 0.25 7.50 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 = AE. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS.
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WM8718 IMPORTANT NOTICE
Production Data
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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