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w WM8741 24-bit 192kHz DAC with Advanced Digital Filtering WOLFSON MICROELECTRONICS plc Production Data, February 2013, Rev 4.3 Copyright 2013 Wolfson Microelectronics plc
DESCRIPTION
The WM8741 is a very high performance stereo DAC designed for audio applications such as professional recording systems, A/V receivers and high specification CD, DVD and home theatre systems. The device supports PCM data input word lengths from 16 to 32-bits and sampling rates up to 192kHz. The WM8741 also supports DSD bit- stream data format, in both direct DSD and PCM-converted DSD modes. The WM8741 includes fine resolution volume and soft mute control, digital de-emphasis and a range of advanced digital filter responses, followed by a digital interpolation filter, multi-bit sigma delta modulator and stereo DAC. Wolfson’s patented architecture optimises the linearity of the DAC and provides maximum insensitivity to clock jitter. The digital filters include se veral selectable roll-off and performance characteristics. The user can select between standard sharp or slow roll-off responses. In addition, the WM8741 includes a selection of advanced digital filter characteristics including non- half band filters and minimum phase filters. This flexibility provides a range of benefits, such as significantly reduced pre-ri nging and minimal group delay. The internal digital filters can also be by-passed and the WM8741 used with an external digital filter. The WM8741 supports two c onnection schemes for audio DAC control. The 2/3 wire seri al control interface provides access to all features. A range of features can also be accessed by hardware control interface. The WM8741 is available in a convenient 28-SSOP package, and is pin compatible with the WM8740.
FEATURES
Advanced Ultra High Perform ance Multi-bit Sigma-Delta Architecture 128dB SNR (‘A’-weighted mono @ 48kHz) 125dB SNR (‘A’-weighted stereo @ 48kHz) 123dB SNR (non-weighted stereo @ 48kHz) -100dB THD @ 48kHz Differential analogue voltage outputs High tolerance to clock jitter PCM Mode Sampling frequency: 32kHz to 192kHz Input data word length support: 16 to 32-bit Supports all standard audio interface formats Selectable advanced digital filter responses Includes linear/minimum phase and range of tailored characteristics Enables low pre-ringing, minimal latency Optional interface to industry standard external filters Digital volume control in 0.125dB steps with soft ramp and soft mute Anti-clipping mode to prevent distortion even with input signals recorded up to 0dB Selectable de-emphasis support Zero Flag output DSD Mode DSD bit-stream support for SACD applications Support for normal or phase modulated bit-streams Direct or PCM converted DSD paths (DSD Plus) DSD mute Hardware or software control modes: 2 and 3 wire serial control interface support Pin compatible with WM8740 4.5V to 5.5V analogue, 3.15V to 3.6V digital supply operation 28-lead SSOP Package
APPLICATIONS
Professional audio systems CD, DVD, SACD audio Home theatre systems A/V receivers
w PD, Rev 4.3, February 2013 BLOCK DIAGRAM DSD ATTENUATION / MUTE DSD TO PCM CONVERTOR PCM ATTENUATION / MUTE AUDIO INTERFACE PCM DIGITAL FILTERS SIGMA DELTA MODULATOR CONTROL INTERFACE PCM DSD PCM ATTENUATION / MUTE SIGMA DELTA MODULATOR MUTEB/SDOUT MODE/LRSEL CSB/SADDR/I2S SDIN/DEEMPH SCLK/DSD ZFLAG DIFFHW DAC LEFT DAC RIGHT VMIDL VOUTLP VOUTLN VOUTRP VOUTRN VMIDR AGNDL AVDDL AGNDR AVDDR AGND AVDD MCLK OSR/DSDR IWO/DOUT LRCLK/DSDL DIN/DINL FSEL/DINR BCLK/DSD64CLK PCM/DSD MUX WM8741
w PD, Rev 4.3, February 2013 TABLE OF CONTENTS
w PD, Rev 4.3, February 2013 PIN CONFIGURATION
ORDERING INFORMATION
RANGE PACKAGE MOISTURE SENSITIVITY LEVEL PEAK SOLDERING TEMPERATURE WM8741GEDS/V -0 to +70C 28-lead SSOP (Pb-free) MSL2 260 ˚C WM8741GEDS/RV -0 to +70C 28-lead SSOP (Pb-free, tape and reel) MSL2 260 ˚C Note: Reel Quantity = 2,000
w PD, Rev 4.3, February 2013 PIN DESCRIPTION (SOFTWARE CONTROL MODE) PIN NAME TYPE DESCRIPTION PCM MODE 8FS PCM MODE DSD MODES
1 LRCLK /
Digital input Audio interface left/right clock input Audio interface left/right clock input DSD left audio data in
2 DIN /
Digital input Audio interface data input Audio interface left data input Unused
3 BCLK /
Digital input Audio interface bit clock input Audio interface bit clock input 64fs system clock input
4 FSEL /
Unused Audio interface right data input Unused
5 MCLK Digital input Master clock input Master clock input Unused
6 DIFFHW Digital input
0 = normal operation 1 = differential mono mode Differential mono mode selection 0 = normal operation 1 = differential mono mode Differential mono mode selection 0 = normal operation 1 = differential mono mode
7 DGND Supply Digital ground Digital ground Digital ground
8 DVDD Supply Digital supply Digital supply Digital supply
9 AVDDR Analogue Input Right analogue positive
10 AGNDR Analogue Input Right analogue negative
11 VMIDR Analogue
12 VOUTRP Analogue
13 VOUTRN Analogue
14 AGND Supply Analogue ground Analogue ground Analogue ground
15 AVDD Supply Analogue supply Analogue supply Analogue supply
16 VOUTLN Analogue
Left DAC negative output Left DAC negative output Left DAC negative output
17 VOUTLP Analogue
Left DAC positive output Left DAC posit ive output Left DAC positive output
18 VMIDL Analogue
19 AGNDL Analogue Input Left analogue negative
20 AVDDL Analogue Input Left analogue positive
21 ZFLAG Digital Output Zero flag output Zero flag output Zero flag output
22 OSR/DSDR Digital input
Unused Unused DSD right audio data in
23 IWO /
w PD, Rev 4.3, February 2013 PIN NAME TYPE DESCRIPTION PCM MODE 8FS PCM MODE DSD MODES
24 MODE /
Digital input, tri-level When DIFFHW=0: 0 = hardware mode 1 = 3-wire software mode Z = 2-wire software mode When DIFFHW=1: 0 = left channel mono 1 = right channel mono When DIFFHW=0: 0 = hardware mode 1 = 3-wire software mode Z = 2-wire software mode When DIFFHW=1: 0 = left channel mono 1 = right channel mono When DIFFHW=0: 0 = hardware mode 1 = 3-wire software mode Z = 2-wire software mode When DIFFHW=1: 0 = left channel mono 1 = right channel mono
25 MUTEB /
output: Internal pull-up Softmute Control 0 = mute active 1 = normal operation NOTE: In 3-wire mode only, this pin may be used as a buffered control interface data output Softmute Control 0 = mute active 1 = normal operation Softute Control 0 = mute active 1 = normal operation Note: In DSD Direct mode this is an analogue mute
26 SDIN /
27 SCLK /
Digital input Serial control interface clock input Serial control interface clock input Serial control interface clock input
28 CSB /
I S Digital input 3-wire mode: serial control interface latch 2-wire mode: device address select 3-wire mode: serial control interface latch 2-wire mode: device address select 3-wire mode: serial control interface latch 2-wire mode: device address select Notes: 1. Undefined inputs should be connected to DVDD or DGND 2. Tri-level pins which require the ‘Z’ st ate to be selected should be left floating (open)
w PD, Rev 4.3, February 2013 PIN DESCRIPTION (HARDWARE CONTROL MODE) PIN NAME TYPE DESCRIPTION PCM MODE DSD DIRECT MODE Digital input Audio interface left/right clock input DSD left audio data in Digital input Audio interface data input Unused Digital input Audio interface bit clock input 64fs system clock input Selects between one of three digital filters – see Table 50 Unused
5 MCLK Digital input Master clock input Unused
Differential mono mode selection 0 = normal operation 1 = differential mono mode Differential mono mode selection 0 = normal operation 1 = differential mono mode
7 DGND Supply Digital ground Digital ground
8 DVDD Supply Digital supply Digital supply
9 AVDDR Analogue Input Right analogue positive reference Right analogue positive reference
10 AGNDR Analogue Input Right analogue negative reference Right analogue negative reference
Right analogue midrail decoupling pin Right analogue midrail decoupling pin Right DAC positive output Right DAC positive output Right DAC negative output Right DAC negative output
14 AGND Supply Analogue ground Analogue ground
15 AVDD Supply Analogue supply Analogue supply
Left DAC negative output Left DAC negative output Left DAC positive output Left DAC positive output Left analogue midrail decoupling pin Left analogue midrail decoupling pin
19 AGNDL Analogue Input Left analogue negative reference Left analogue negative reference
20 AVDDL Analogue Input Left analogue positive reference Left analogue positive reference
21 ZFLAG Digital Output Zero flag output Unused
Controls internal oversampling rate: 0 = low rate Z = medium rate 1 = high rate DSD right audio data in Controls audio interface wordlength – see Table 46 Unused
w PD, Rev 4.3, February 2013 PIN NAME TYPE DESCRIPTION PCM MODE DSD DIRECT MODE Digital input, tri-level When DIFFHW=0: 0 = hardware mode 1 = 3-wire software mode Z = 2-wire software mode When DIFFHW=1: 0 = left channel mono 1 = right channel mono When DIFFHW=0: 0 = hardware mode 1 = 3-wire software mode Z = 2-wire software mode When DIFFHW=1: 0 = left channel mono 1 = right channel mono output: Internal pull-up Softmute Control 0 = mute active 1 = normal operation Analogue Mute Control 0 = mute active 1 = normal operation 0 = normal operation 1 = de-emphasis applied Z = anti-clipping digital filter mode Unused Digital input HW Mode Select: 0 = PCM 1 = DSD Direct HW Mode Select: 0 = PCM 1 = DSD Direct I S Digital input Controls audio interface format – see Table 46 Unused Notes: 1. Undefined inputs should be connected to DVDD or DGND 2. Tri-level pins who require the ‘Z’ stat e to be selected should be left floating (open)
w PD, Rev 4.3, February 2013 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 specificati ons are given under Electrica l 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 Microelectronics tests its package types according to IPC/JEDEC J-STD-020 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 MIN MAX Digital supply voltage, DVDD -0.3V +4.5V Analogue supply voltage, AVDD -0.3V +7V Voltage range digital inputs DGND - 0.3V DVDD + 0.3V Voltage range analogue inputs AGND - 0.3V AVDD + 0.3V Master Clock Frequency 38.462MHz Operating temperature range, TA -0°C +70°C Storage temperature -65°C +150°C Ambient temperature (supplies applied) -55°C +125°C Pb free package body temperature (soldering 10 seconds) +260°C Pb free package body temperature (soldering 2 minutes) +183°C Notes: 1. Analogue and digital grounds must always be within 0.3V of each other. THERMAL PERFORMANCE PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Thermal resistance – junction to case θJC 23.9 °C/W Thermal resistance – junction to ambient θJA 67.1 °C/W
w PD, Rev 4.3, February 2013 RECOMMENDED OPERATING CONDITIONS PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Digital supply range DVDD 3.15 3.3 3.6 V Analogue supply range AVDD 4.5 5 5.5 V Ground AGND, DGND 0 V Difference DGND to AGND -0.3 0 +0.3 V Analogue operating current IAVDD AVDD = 5V 55 mA Digital operating current IDVDD DVDD = 3.3V 40 mA Analogue standby current IAVDD (Standby) AVDD = 5V Clocks stopped 45 mA Digital standby current IDVDD (Standby) DVDD = 3.3V Clocks stopped 1.5 mA
ELECTRICAL CHARACTERISTICS
AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, T A = +25 o C, 1kHz test signal, fs = 48kHz, MCLK = 512fs unless otherwise stated. PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Digital Logic Levels Input LOW level VIL 0.3 x DVDD V Input HIGH level VIH 0.7 x DVDD V Output LOW level VOL I OL = 2mA 0.1 x DVDD V Output HIGH level VOH I OH = 2mA 0.9 x DVDD V DSD Input Characteristics DSD reference level DSD Direct or DSD Plus Mode 0 dB DSD DAC Performance Signal to Noise Ratio (Note 1) SNR A-weighted mono @ fs = 48kHz 128 dB A-weighted stereo @ fs = 48kHz 120 125 dB A-weighted stereo @ fs = 96kHz 123 dB A-weighted stereo @ fs = 192kHz 120 dB Non-weighted stereo @ fs = 48kHz 122 dB Dynamic Range (Note 2) DNR A=weighted, -60dB full scale input 125 dB Total Harmonic Distortion (Note 2) THD Mono 0dB @ fs = 48kHz -100 dB Stereo 0dB @ fs = 48kHz -100 dB Stereo 0dB @ fs = 96kHz -100 dB Stereo 0dB @ fs = 192kHz -100 dB Channel Separation 1kHz 130 dB Channel Level Matching 0.1 dB Channel Phase Deviation 0.01 Degree Power Supply Rejection Ratio PSRR 100mVpp at 1kHz -80 dB 20Hz to 20kHz 100mVpp -67 dB
w PD, Rev 4.3, February 2013 TEST CONDITIONS AVDD = 5V, DVDD = 3.3V, AGND, DGND = 0V, T A = +25 o C, 1kHz test signal, fs = 48kHz, MCLK = 512fs unless otherwise stated. PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Internal Analogue Filter Bandwidth -3dB 474 kHz Passband edge response 20kHz -0.0077 dB Analogue Output Levels PCM full scale differential output level Into 10k Ω load, 0dBFS input 2 VRMS DSD Direct differential output level Into 10k Ω load, 0dBDSD input 0.948 VRMS DSD Plus differential output level Into 10k Ω load, 0dBDSD input 0.991 VRMS Minimum resistance load To midrail or AC coupled 2 k Ω Maximum capacitance load 1 nF Output DC level AVDD/2 V Reference Levels Potential divider resistance AVDD to VMIDL/VMIDR and VMIDL/VMIDR to AGND 10 k Ω Voltage at VMIDL/VMIDR AVDD/2 V Notes: 1. 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. 2. All performance measurements done with 20kHz low pass filter. Failure to use such a filter will result in higher THD 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.
w PD, Rev 4.3, February 2013 CONTROL INTERFACE TIMING – 3-WIRE MODE Figure 5 Control Interface Timing - 3-Wire Serial Control Mode Test Conditions DVDD = 3.3V, GND = 0V, T A = +25 o C, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT SCLK rising edge to LATCH rising edge tSCS 40 ns SCLK pulse cycle time tSCY 80 ns SCLK pulse width low tSCL 32 ns SCLK pulse width high tSCH 32 ns SDIN to SCLK set-up time tDSU 20 ns SCLK to SDIN hold time tDHO 20 ns LATCH pulse width low tCSL 20 ns LATCH pulse width high tCSH 20 ns LATCH rising to SCLK rising tCSS 20 ns Table 4 Control Interface Timing – 3-Wire Serial Control Mode
w PD, Rev 4.3, February 2013 CONTROL INTERFACE TIMING – 2-WIRE MODE Figure 6 Control Interface Timing - 2-Wire Serial Control Mode Test Conditions DVDD = 3.3V, DGND = 0V, TA = +25 o C, Slave Mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SYMBOL MIN TYP MAX UNIT SCLK Frequency 0 5 MHz SCLK Low Pulse-Width tSCL 80 ns SCLK High Pulse-Width tSCH 80 us Hold Time (Start Condition) tHOL 600 ns Setup Time (Start Condition) tCSE 600 ns Data Setup Time tDSU 100 ns SDIN, SCLK Rise Time tRIS 300 ns SDIN, SCLK Fall Time tFAL 300 ns Setup Time (Stop Condition) tCSS 600 ns Data Hold Time tDHO 900 ns Max Pulse width of spikes that will be suppressed tPS 4 6 ns Table 5 Control Interface Timing – 2-wire Serial Control Mode
w PD, Rev 4.3, February 2013 INTERNAL POWER ON RESET CIRCUIT The WM8741 includes two internal Power On Reset (POR ) circuits which are used to reset the digital logic into a default state after power up and to allow the analogue circuits to power-up silently. The digital POR circuit is powered from DVDD. This circuit monito rs DVDD and asserts the internal digital reset if DVDD are below the minimum DVDD threshold which will allow the digital logic to function. The analogue POR circuit is powered from AVDD. T he circuit monitors AVDD, tri-stating the DAC outputs and isolating the internal reference resi stor strings from AVDDL and AVDDR until there is sufficient AVDD voltage to allow the analogue DAC stages to function correctly. Figure 7 AVDD Power up Sequence Test Conditions AVDD = 5V, AGND = 0V, T A = +25 o C, TA_max = +125 o C, TA_min = -25 o C, AVDDmax = 5.5V, AVDDmin = 4.5V PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Power Supply Input Timing Information AVDD level to POR rising edge (AVDD rising) Vpor_hi Measured from AGND 2.00 V AVDD level to POR falling edge (AVDD falling) Vpor_lo Measured from AGND 1.84 V Table 6 Analogue POR Timing
w PD, Rev 4.3, February 2013 DEVICE DESCRIPTION INTRODUCTION The WM8741 is an ultra high perform ance DAC designed for digital audi o applications. Its range of features makes it ideally suited for use in prof essional recording environments, CD/DVD players, AV receivers and other high-end consumer audio equipment. The WM8741 is a complete differential stereo audi o digital-to-analogue converter. The system includes a dithered digital interpolation filter, fi ne resolution volume control and digital de-emphasis, followed by a multi-bit sigma delta modulator and sw itched capacitor multi-bit stage with differential voltage outputs. The device supports both PCM and DSD digital audio input formats. The WM8741 includes a configurable digital audio interface support fo r a 3-wire and 2-wire serial control interface, and a hardware control interface. The software control interface may be asynchronous to the audio data interface; in which case control data will be re-synchronised to the audio processing internally. It is fully compatible with, and an ideal partner for, a range of industry standard microprocessors, controllers and DSPs. Uniquely, the WM8741 has a large range of high perfo rmance low latency advanced digital filters. The full range of filters is selectable in softwar e mode, and a limited range of filters are available under hardware control. The filters allow users the flexibility to choose charac teristics to match their group delay, phase and latency requirements. Operation using a master clock of 128fs, 192fs, 256fs, 384fs, 512fs or 768fs is supported. Sample rates (fs) from 32kHz to 192kHz are allowed, pr ovided the appropriate master clock is input (see Table 11 for details). In normal PCM mode, the audio data interface supports right justified, left justified and I S interface formats along with a highly flexible DSP serial port interface. There are two DSD modes. In DSD Direct mode, the datastream is subjected to the minimum possible processing steps between input and output. In DSD Plus mode, the datastream is converted to PCM and filtered to allow reduction of out of band components. This step also provides additional benefits in allowing access to other PCM features such as volume control and advanced digital filtering. The device is packaged in a small 28-lead SSOP. CLOCKING SCHEMES In a typical digital audio system there is only one c entral 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 ma ster system clock can be applied directly through the MCLK input pin with no software configuration necessary for sample rate selection. MCLK is used to derive clocks for the DAC path in PCM mode. The DAC path consists of DAC sampling clock, DAC digital filter clock and DAC di gital audio interface timing. In a system where there are a number of possible sources for the re ference clock it is recommended that the clock source with the lowest jitter be used to optimise the performance of the DAC. CONTROL INTERFACE The WM8741 supports 2-wire and 3-wire serial contro l, and hardware control. Selection of control mode is made by controlling the state of the MODE pin. PIN NAME DESCRIPTION
24 MODE/
0 = Hardware control mode 1 = 3-wire serial control mode Z = 2-wire serial control mode Table 8 Control Mode Configuration
w PD, Rev 4.3, February 2013 Figure 11 Initial Setup of Two WM8741 Devices into Control Interface Daisy Chain Mode To write to a single device in the chain a comple te sequence needs to be written to all the devices. Devices that do not require a register change must al so be written to. The user can choose to write either the same data as the previous write, or writ e all 1s for the register address and data. All 1s will result in writing to a non-existent register, addre ss 7Fh, preserving the curr ent register settings. Figure 12 shows an example of how to acce ss three WM8741 devices (the devices have all previously been configured in daisy chain mode): Figure 12 Daisy Chain Control Interface Example for Three WM8741 Devices To ensure that only valid data is written to the devic es in daisy chain mode, a pull up resistor is used in SDOUT. When connected to the SDIN pin of the next device in the chain, this results in all ones being written to the control interface of that dev ice until the correct daisy chain data is written and latched. Serial daisy chaining is available only when using 3-wire serial contro l mode. It is not available in 2- wire serial control mode or hardware control mode. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 2 08h
5 SDOUT 0 3 wire Serial Interface Daisy Chaining
0 = No Output 1 = Output on pin 25. Table 9 Control Interface Daisy Chaining Selection
w PD, Rev 4.3, February 2013 2-WIRE SERIAL CONTROL MODE The WM8741 supports software control via a 2-wire se rial 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 WM8741). The WM8741 operates as a slave device on the 2-wire control bus. 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 WM8741 and the R/ W bit is ‘0’, indicating a write, then the WM8741 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 WM8741 return s to the idle condition and wait for a new start condition and valid address. Once the WM8741 has acknowledged a correct address, t he controller sends the first byte of control data (B15 to B8, i.e. the WM8741 register address pl us the first bit of register data). The WM8741 then acknowledges the first data byte by pulling SD IN 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 WM8741 acknowledges again by pulling SDIN low. The transfer of data is complete when there is a lo w to high transition on SDIN while SCLK is high. After receiving a complete address and data sequence the WM8741 returns to the idle state and waits for another start condition. If a start or st op condition is detected out of sequence at any point during data transfer (i.e. SDIN changes while SCLK is high), the device reverts to the idle condition. Figure 13 2-wire Serial Control Interface The WM8741 device address can be configured between two options. This is selected by the SADDR pin. PIN NAME DESCRIPTION
28 CSB/
S 0 = 2-wire address 0011010 1 = 2-wire address 0011011 Table 10 2-wire Serial Control Mode Address Selection DIGITAL AUDIO INTERFACE PCM MODE There are a number of valid PCM data input m odes. Two channel and one channel differential mono modes can be selected by serial or hardware control. It is also possible to bypass the WM8741 digital filters and apply a signal at a rate 8fs (where fs is t he sampling rate) directly to the switched capacitor stage..
w PD, Rev 4.3, February 2013 PCM DIGITAL AUDIO INTERFACE Audio data is applied to the DAC system via the Di gital Audio Interface. Five popular interface formats are supported: Left Justified mode Right Justified mode I S mode DSP mode A DSP mode B All five formats require the MSB to be transmitt ed first, and support word lengths of 16, 20, 24 and 32 bits, with the exception that 32 bit data is not s upported in right justified mode. DIN and LRCLK may be configured to be sampled on the rising or falling edge of BCLK by adjusting register bits LRP and BCP. In left justified, right justified and I S audio interface modes, the digita l audio interface receives data on the DIN input pin. Stereo audio data is time mu ltiplexed on DIN, with LRCLK indicating whether the left or right channel is present. LRCLK is al so used as a timing reference to indicate the beginning or end of the data words. The minimum number of BCLK periods per LRCLK per iod is two times the selected word length. LRCLK must be high for a period equal to the mi nimum number of BCLK periods, and low for a minimum of the same period. Any mark-to-spac e ratio on LRCLK is acceptable provided the above requirements are met. The WM8741 will automatically detect when data with a LRCLK period of exactly 32 BCLKs is received, and select 16-bit mode. This overrides any previously programmed word length. The operating word length will revert to a programmed value only if a LRCLK period other than 32 BCLKs is detected. In DSP mode A or DSP mode B, the data is time multiplexed onto DIN. LRCLK is used as a frame sync signal to identify the MSB of the first word. The minimum number of BCLKs per LRCLK period is two times the selected word length. Any mark to space ratio is accept able on LRCLK provided the rising edge is correctly positioned. LEFT JUSTIFIED MODE In left justified mode, the MSB is sampled on the first rising edge of BCLK following a LRCLK transition. LRCLK is high during the left data word and low during the right data word. Figure 14 Left Justified Mode Timing Diagram
w PD, Rev 4.3, February 2013 In both modes the polarity of LRCLK can be switched using register bit LRP. 8FS MODE SAMPLING RATES Since the data rate in 8FS mode is much faster than in standard PCM mode, there are restrictions on the MCLK rate that can be used. Specifically , only 512fs and 768fs modes are permitted restricting the sample rate to a maximum of 8x48kHz. The master clock should be synchronised with LRCLK, although the WM8741 is tolerant of phase differences or jitter on this clock. Unlike in normal PCM mode, the master clock detec tion circuit does not operate in 8FS mode. The rate must be manually programmed using the control interface. SAMPLING RATE LRCLK FREQUENCY (kHz) MASTER CLOCK (MCLK) FREQUENCY (MHz) fs 8fs 512fs 768fs 32kHz 256 16.384 24.576 44.1kHz 352.8 22.5792 33.8688 48kHz 384 24.576 36.864 Table 12 Typical Relationships between Master Clock Frequency and Sampling Rate in 8FS Mode AUDIO INTERFACE DAISY CHAINING In daisy chain mode the DOUT pin outputs the audi o data received on the DIN pin but delayed by two times the input word length. When this output is connected to the DIN pin of the next device in the chain, each WM8741 device will simultaneously sample different channel data in the same LRCLK period. Daisy chaining is only available in DSP audio interface mode and is limited by a maximum BCLK frequency of 24.576MHz. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 2 08h
4 DOUT 0 Daisy Chaining Multiple devices –
multichannel off one PCM feed. 0 = No Output 1 = Output on pin 23. Table 13 Daisy Chaining Audio Data Output Control The following diagram illustrates timing for a daisy chain with 2 WM8741 devices. Figure 21 Audio Interface Daisy Chaining Timing
w PD, Rev 4.3, February 2013 DSD MODE The WM8741 supports DSD input bitstreams at 64x the oversampling rate. The data is supplied at a rate of 64 bits per normal word clock. In DSD, no word clock is provided. The WM8741 supports two channels of bitstream or DSD audio. Data bitstreams and the 64fs clock are supplied to pins 1, 22 and 3 respectively. T he MODESEL[1:0] register bits control whether the device operates in DSD direct, DSD plus or PCM modes. DSD DIRECT In DSD Direct mode the internal digital filters are bypassed, the input bitstr eam data is subjected to the minimal possible processing and is applied direct ly to the switched capacitor stage of the DAC system. Using this mode provides the purest possible representation of a DSD stream. It is normally desirable to use an external analogue post-DAC analogue filter to combine the differential outputs of the DAC and remove high frequenc y energy from the output. This is particularly important in the case of DSD operation due to the presence of high frequency energy which is a result of the aggressive high order noise shaping used in the creation of the modulated DSD datastream. DSD PLUS MODE In DSD Plus mode the DSD data can be filtered in a similar manner to the data in the PCM path. The DSD Plus filters are selected using register bits DSDFILT[1:0]. DSD Plus mode is not available under hardware control. Although DSD Plus mode requires that the bitstream is more heavily processed than DSD Direct, the advantage is that DSD Plus mode reduces the hi gh frequency energy which is a result of the aggressive high order noise shaping used in the cr eation of the modulated DSD datastream. This means that a less aggressive, lower order, analogue filter can be used at the output. Furthermore the slew-rate requirements of the op-amps can be relaxed compared to DSD direct mode, due to the reduction in high frequency energy. DSD DIGITAL AUDIO INTERFACE DSD audio data is input to the WM8741 via the DSD di gital audio interface. Two interface formats are supported: Uni-phase Bi-phase To use this interface apply left data on input pi n 1 (LRCLK/DSDL) and pin 22 (OSR/DSDR). A DSD clock is also required, running at 64FS, and should be applied to pin 3 (BCLK/DSD64CLK). Figure 22 Uni-phase DSD Mode Timing Diagram
w PD, Rev 4.3, February 2013 Figure 23 Bi-phase DSD Mode Timing Diagram SOFTWARE CONTROL MODE Software control allows access to all features of the WM8741. Selection of control mode is achieved by configuring the state of MODE/LRSEL (pin 24): PIN NAME DESCRIPTION 0 = Hardware control mode 1 = 3-wire serial control mode Z = 2-wire serial control mode Table 14 Control Mode Configuration DSD AND PCM MODE SWITCHING The audio interface mode can be switched between DSD and PCM by writing MODESEL[1:0] in R7. It is recommended that the chip is forced into a MUTE state before dynamically switching modes. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 1 07h [1:0] MODESEL 00 DSD/PCM mode select : 00 = PCM mode 01 = Direct DSD Operation 10 = DSD plus mode 11 = Unused Table 15 PCM/DSD Software Mode Selection PCM DIGITAL AUDIO INTERFACE CONTROL REGISTERS The PCM digital audio input format is configured by register bits FMT [1:0] and IWL[1:0]: REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Format Control 05h 1:0 IWL[1:0] 10 Audio interface input word length select 00 = 16-bit 01 = 20-bit 10 = 24-bit 11 = 32-bit 3:2 FMT[1:0] 10 Audio interface input format select 00 = Right justified 01 = Left justified 10 = I S 11 = DSP Table 16 Interface Format Controls Note: 1. In all modes, the data is signed 2's complement. The WM8741 digital filters always input 24-bit data. If the interface is programmed into 32 bits, dither is applied according to Table 37 before truncation to the internal wordlength.
w PD, Rev 4.3, February 2013 LRCLK POLARITY In left justified, right justified or I S modes, the LRP register bit controls the polarity of LRCLK. If this bit is set high, the expected polarity of LRCLK w ill be the opposite of that shown in Figure 14, Figure 15 and Figure 16. 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 BIT LABEL DEFAULT DESCRIPTION Format Control 05h
4 LRP 0 LRCLK polarity select:
0 = normal LRCLK polarity 1 = inverted LRCLK polarity Table 17 LRCLK Polarity Control In DSP modes, the LRP register bit is used to select between DSP mode A and B (see Figure 17 and Figure 18). REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Format Control 05h
4 LRP 0 DSP format select:
0 = DSP mode A 1 = DSP mode B Table 18 DSP Format Control BCLK / DSDCLK64 POLARITY In PCM mode, LRCLK and DIN are sampled on the rising edge of BCLK by default, and should ideally change on the falling edge. Data sources which change LRCLK and DIN on the rising edge of BCLK can be supported by setting the BCP register bit. Setti ng BCP to 1 inverts the polarity of BCLK to the inverse of that shown in Figure 14, Figure 15, Figure 16, Figure 17 and Figure 18. In DSD mode, DSDL and DSDR inputs are sampled a fixed delay after a falling 64fs clock edge. When BCP is set in DSD mode, DSDL and DSDR are sampled a fixed delay after a rising 64fs clock edge. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Format Control 05h
5 BCP 0 BCLK / DSD64CLK polarity select:
0 = normal polarity 1 = inverted polarity Table 19 BCLK Polarity Control OVERSAMPLING RATE CONTROL The user has control of the oversampling ratio of the WM8741, and can set to the device to operate in low, medium or high rate modes. For correct operat ion of the digital filtering and other processing on the WM8741, the user must ensure the correct value of OSR[1:0] is set at all times. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 1 07h [6:5] OSR[1:0] 00 Oversampling Rate Selection 00 = Low rate (32/44.1/48kHz) 01 = Medium rate (96kHz) 10 = High rate (192kHz) 11 = Unused Table 20 Oversampling Rate Control
w PD, Rev 4.3, February 2013 MCLK/LRCLK RATIO CONTROL (NORMAL PCM MODE) The ratio of MCLK/LRCLK can be programmed directly or auto-detected. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 1 07h [4:2] SR[3:0] 000 MCLK to LRCLK sampling rate ratio control (Normal PCM Mode): 000 = auto detect sample rate 001 = 128fs 010 = 192fs 011 = 256fs 100 = 384fs 101 = 512fs 110 = 768fs 111 = reserved Table 21 MCLK/LRCLK Ratio Control (Normal PCM Mode) 8FS MODE 8FS Mode allows the use of custom digital filters by bypassing the WM8741 internal digital filters. When MODE8X is set, the PCM data input to the WM8741 is applied only to the digital volume control and then the analogue section of the DAC system, bypassing the digital filters. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Format Control 07h
7 MODE8X 0 8FS mode select:
0 = Normal operation 1 = 8FS mode (digital filters bypassed) Table 22 8FS Mode Control MCLK/LRCLK RATIO CONTROL (8FS MODE) In 8FS mode the choice of clock ratios and samp ling rates is limited – see Table 12 for details. Autodetect of MCLK/LRCLK ratio is not available in 8FS mode and must be set manually by the user for correct operation. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 1 07h [4:2] SR[2:0] 000 MCLK to LRCLK sampling rate ratio control (8FS Mode): 000 = reserved 001 = 512fs 010 = 768fs 011 to 111 = reserved Table 23 MCLK/LRCLK Ratio Control (8FS Mode) ATTENUATION CONTROL Each DAC channel can be attenuated digitally before bei ng applied to the digital filter. Attenuation is set to 0dB by default but can be set between 0dB and -127.5dB in 0.125dB steps using the ten attenuation control bits LAT[4:0], LAT[9:5], RAT[4:0] and RAT[9:5]. All attenuation registers are double latched allowi ng 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.
w PD, Rev 4.3, February 2013 REGISTER ADDRESS BITS LABEL DEFAULT DESCRIPTION DACLLSB Attenuation 00h [4:0] LAT[4:0] 00 (0dB) LSBs of attenuation data for left channel in 0.125dB steps. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for left channel. 0 = Store LAT[4:0] value but don’t update 1 = Store LAT[4:0] and update attenuation on registers 0-3 DACLMSB Attenuation 01h [4:0] LAT[9:5] 00 (0dB) MSBs of attenuation data for left channel in 4dB steps. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for left channel. 0 = Store LAT[9:5] value but don’t update 1 = Store LAT[9:5] and update attenuation on registers 0-3 DACRLSB Attenuation 02h [4:0] RAT[4:0] 00 (0dB) LSBs of attenuation data for right channel in 0.125dB steps. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for right channel. 0 = Store RAT[4:0] value but don’t update 1 = Store RAT[4:0] and update attenuation on registers 0-3 DACRMSB Attenuation 03h [4:0] RAT[9:5] 00 (0dB) MSBs of attenuation data for right channel in 4dB step. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for right channel. 0 = Store RAT[9:5] value but don’t update 1 = Store RAT[9:5] and update attenuation on registers 0-3 Table 24 Attenuation Control Note: 1. The UPDATE bit is not latched. If UPDATE=0, the attenuat ion 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. DAC OUTPUT ATTENUATION Registers LAT[9:0] and RAT[9:0] control the left and right channel attenuation. Table 25 shows how the attenuation levels are configured by the 10-bit words. L/RAT[9:0] ATTENUATION LEVEL 000(hex) 0dB 001(hex) -0.125dB : : : : : : 3FE(hex) -127.75dB 3FF(hex) - dB (mute) Table 25 Attenuation Control Levels ATTENUATION CONTROL MODE 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 samp le. No update to the attenuation registers is required for ATC to take effect. Right channels r egister settings are preserved regardless of the status of ATC. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Volume Control 04h
2 ATC 0 Attenuator Control Mode:
0 = Right channels use Right attenuation 1 = Right Channels use Left Attenuation Table 26 Attenuator Control Mode
w PD, Rev 4.3, February 2013 VOLUME RAMP MODE There are two ways to change the volume in the WM8741, controlled by VOL_RAMP. When VOL_RAMP=0, the volume changes in a single step from the current volume setting to the new volume when an update is applied to the gain control registers. When VOL_RAMP=1, the volume is automatically ramped from the current volume setting to the new volume setting when an update is applied to the volume control registers. The speed at which this happens is dependant on the sample rate as shown in Table 27 below: SAMPLE RATE (kHz) RAMP RATE (ms/dB) 32 1.000 44.1 0.726 48 0.667 88.2 0.726 96 0.667 176.4 0.726 196 0.667 Table 27 Volume Ramp Rates REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Volume Control 04h
0 VOL_
0 Volume ramp mode control:
0 = Apply volume change in a single step. 1 = Ramp between current volume setting and new volume setting. Table 28 Volume Ramp Control ANTI-CLIPPING DIGITAL ATTENUATION MODE Audio material is regularly recorded up to 0dB level and heavily compressed. This may cause clipping and occasional distortion when t he digital media is applied to a DA C. In order to prevent this in the WM8741, an anti-clipping mode is provided, whic h attenuates the digital signal by 2dB as it is processed through the digital filters. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Volume Control 04h
1 ATT2DB 0 Anti-clipping mode control:
0 = Off, 0dB attenuation 1 = On, 2dB attenuation applied Table 29 Anti-Clipping Digital Attenuation Control DSD PLUS GAIN CONTROL The gain in the DSD Plus data path can be adjus ted. The default setting provides a 1.4Vrms differential output level. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 2 08h
6 DSD_
0 DSD Plus gain control:
0 = Low gain, 1.4Vrms differential output level 1 = High gain, 2.0Vrms differential output level Table 30 DSD Plus Gain Control
w PD, Rev 4.3, February 2013 MUTE MODES Time (s) Figure 24 Application and Release of Soft Mute Figure 24 shows the application and release of SO FTMUTE for a full amplitude sinusoid being played at 48kHz sampling rate. When SOFTMUTE (lower trace) is asserted, the WM8741 output (upper trace) begins to decay exponentially from the DC leve l of the last input sample. The output decays towards VMID in 1022x4/fs seconds. When SOFTMUTE is de-asserted, the signal gain will return to its previous value. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION PCM Control 04h
3 SOFTMUTE 0 Soft mute select
0 = Normal operation 1 = Soft mute both channels Table 31 Soft Mute Control
w PD, Rev 4.3, February 2013 ZERO FLAG OUTPUT The WM8741 has one zero flag output pin, ZFLAG (pin 21). The zero flag feature is only valid for PCM data. The WM8741 asserts Logic 1 on the ZFLAG pin when a sequence of more than 1024 zeros is input to the chip. The default value is a logical AND of both left and right channels. Under software control, the user can also set the zero flag pin to respond to either the left channel OR the right channel. The zero flag pin can be used to control external muting circuits if required. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Volume Control 04h 6:5 ZEROFLR [1:0]
00 Zero flag output:
00 = Pin assigned to logical AND of LEFT and RIGHT channels 01 = Pin assigned to LEFT channel 10 = Pin assigned to RIGHT channel 11 = ZFLAG disabled Table 32 Zero Flag Output ZFLAG FORCE HIGH CONTROL It is possible to force the ZFLAG pin to Logic 1 by setting ZFLAG_HI=1 in R7. This is useful in situations where an application proc essor may require manual control of an external mute circuit. Setting ZFLAG_HI=0 will allow the ZFLAG pin to function as defined by ZFLAGLR[1:0]. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 1 06h
7 ZFLAG_HI 0 ZFLAG Force High Control
0 = Normal operation 1 = Output Logic 1 Table 33 ZFLAG Force High Control INFINITE ZERO DETECT The IZD register configures the operation of t he WM8741 analogue mute in conjunction with the zero flag feature. Table 20 shows the interdependency of the MUTEB pin, the IZD register and the zero flag. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Volume Control 04h
4 IZD 0 IZD control of analogue mute:
0 = Never analogue mute 1 = Analogue mute when ZFLAG set Table 20 Infinite Zero Detect Control
w PD, Rev 4.3, February 2013 MUTEB ZFLAG DAC DINL DINR ZDET ANA L&R SOFT L&R DSD Direct Infinite Zero Detect Figure 25 Software Control Mode MUTEB and ZFLAG Configuration DE-EMPHASIS Setting the DEEMPH[1:0] register bits enables de- emphasis support in the WM8741 digital filters. There are three de-emphasis filters, one each for sampling rates of 32kHz, 44.1kHz and 48kHz. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Filter Control 06h [6:5] DEEMPH [1:0]
00 De-emphasis mode select:
00 = De-emphasis Off 01 = De-emphasis 32kHz 10 = De-emphasis 44.1kHz 11 = De-emphasis 48kHz Table 34 De-emphasis 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. Note: The REV bit can only be used in stereo mode. When in differential mono mode, the REV bit must remain set as 0. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Format Control 05h
6 REV 0 Analogue output phase control:
0 = Normal 1 = Inverted Table 35 Output Phase Control
w PD, Rev 4.3, February 2013 DIFFERENTIAL MONO MODE DIFF[1:0] sets the required differential output mode; normal stereo, reversed stereo, mono left or mono right, as shown in Table 36. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 2 08h [3:2] DIFF[1:0] 00 00 = Stereo 10 = Stereo reverse (left and right channels swapped) 01 = 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. 11 = 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. Table 36 Differential Output Modes Using these controls a pair of WM8741 devices may be used to build a dual differential stereo implementation with higher performance and differential output. DITHER Dither is applied whenever internal truncation occu rs. It is also used when a 32 bit input word is applied to the DAC prior to truncation to the inte rnal wordlength. Three types of dither can be selected to allow the sound quality if the device to be optimised. TDF has a triangular probability density function and causes zero noise modulation i.e. the quantisation noise is invariant to the changes in the signal level. This mode is recommended and is selected by default. RPDF has a rectangular probability density function and may cause noise modulation. HPDF has a triangular probability density function with a high pass characteristic, which has a lower noise at low frequencies at the expense of raised noise levels at higher frequencies. Alternatively the dither can be disabled. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Mode Control 2 08h [1:0] DITHER [1:0]
10 Digital filter dither mode select:
00 = dither off 01 = RPDF dither applied in Digital filter 10 = TPDF dither applied in Digital filter 11 = HPDF dither applied in Digital filter Note: DITHER[1:0] applies only to the dither mode in the Digital filter. Table 37 Dither Control
w PD, Rev 4.3, February 2013 NORMAL PCM MODE DIGITAL FILTER SELECTION The WM8741 has a number of advanced digital filters that can be selected in all PCM operation modes (with the exception of 8FS mode). REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Filter Control 06h [2:0] FIRSEL 000 Selects FIR1 filter response 000 = Response 1 001 = Response 2 010 = Response 3 011 = Response 4 100 = Response 5 Table 38 PCM Advanced Digital Filter Selection Five digital filters are available for selection in each of the three OSR m odes (low, medium and high rate) as selected by the OSR bit described in Tabl e 20. It is recommended that the device is muted before the filter response is changed to prevent noise as the filters are reset from appearing on the outputs. A summary of the filter characteristics is given in Table 39 below: OSR RESPONSE NOTES Low 1 Linear phase half-band filter for backward compatibility
2 Minimum phase ‘soft-knee’ filter
3 Minimum phase half-band filter
4 Linear phase apodising filter
5 Minimum phase apodising filter
Medium 1 Linear phase ‘soft-knee’ filter
3 Linear phase ‘brickwall’ filter
4 Minimum phase apodising filter
5 Linear phase apodising filter
High 1 Linear phase ‘soft-knee’ filter Table 39 PCM Digital Filter Summary For full details of the filter characteristics av ailable in normal PCM mode, please see Table 64 to Table 66 and Figure 28 to Figure 57. 8FS MODE DIGITAL FILTER In 8FS mode, the majority of the internal filters ar e bypassed. In this mode, the data is filtered using only the filter characteristic described by Table 67 and shown in Figure 58 and Figure 59. DSD PLUS FILTER SELECTION The WM8741 has a number of compensation filters that can be selected in DSD Plus mode. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Filter Control 06h [4:3] DSDFILT [1:0]
00 Selects Compensation Filter
00 = Response 1 01 = Response 2 10 = Response 3 11 = Response 4 Table 40 DSD Plus Digital Filter Selection
w PD, Rev 4.3, February 2013 It is recommended that the device is muted before t he filter response is changed to prevent noise as the filters are reset from appearing on the outputs. Full details of these filters are described in Table 68 and Figure 60 to Figure 67. DSD DIRECT DIGITAL FILTERS The DSD Direct filters have been designed to provide the minimal of processing to the data with no decimation, re-quantisation or noise -shaping, in order to preserve t he signal integrity as much as possible. As a result the filters have a wide bandwidth and a very gradual attenuation. It is recommended that whichever DSD Direct filter is chosen it is augmented by analogue post-DAC filtering in order to adhere to the Scarlet-Book SACD standard. There are a total of four DSD Direct filter respons es available, controlled by two register bits as described in Table 41 below: REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION R32 Additional Control 1 20h
0 DSD_NO_
0 DSD Direct 8fs Notch Filter
0: Enable 8fs notch filter 1: Disable 8fs notch filter
1 DSD_
1 DSD Direct Filter Gain
0: High gain 1: Low gain Table 41 DSD Direct Digital Filter Selection DSD MUTE CONTROL In DSD Direct mode, an analogue mute can be applied at the output of the DAC. This is controlled by register bit AMUTE. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Volume Control 04h
7 AMUTE 0 DSD Direct mute control:
0 = mute off 1 = mute on Table 42 DSD Analogue Mute Control POWER SAVING STANDBY CONTROL Setting the PWDN register bit imm ediately connects all outputs to V MID and resets the digital sections of the DAC system including the DLL, the audio interface and the DSP. Input data samples are not preserved, but all control register settings ar e maintained. When PWDN is cleared the WM8741 will repeat its power-on initialisation sequence. REGISTER ADDRESS BIT LABEL DEFAULT DESCRIPTION Format Control 05h
7 PWDN 0 Power Down Mode Select:
0 = Normal Mode 1 = Power Down Mode Table 43 Powerdown Control
w PD, Rev 4.3, February 2013 HARDWARE CONTROL MODE When the MODE pin is held ‘low’ the WM8741 is set to hardware control mode and a limited feature set can be configured. PIN NAME DESCRIPTION 0 = Hardware control mode 1 = 3-wire serial control mode Z = 2-wire serial control mode Table 44 MODE/LRSEL Hardware Control Pin Function DSD AND PCM MODE SWITCHING The audio interface mode can be switched between DS D Direct and PCM by controlling the state of pin DSD. It is recommended that the chip is forc ed into a MUTE state before dynamically switching modes. PIN NAME DESCRIPTION
27 SCLK/DSD 0 = PCM Mode
1 = DSD Direct Mode Table 45 SCLK/DSD Hardware Control Pin Function AUDIO INPUT FORMAT Under hardware control, it is possible to select between four different modes of operation for the PCM audio interface. PIN NUMBER 28 23 DESCRIPTION NAME CSB/SADDR/I2S IWO/DOUT STATUS 0 0 16-bit right justified 0 1 24-bit right justified 1 0 24-bit left justified 1 1 24-bit I S Table 46 CSB/SADDR/I2S and IWO/DOUT Hardware Control Pin Function
w PD, Rev 4.3, February 2013 OVERSAMPLING RATE CONTROL The user has control of the oversampling ratio of the WM8741, and can set to the device to operate in low, medium or high rate modes. For optimum oper ation of the digital filtering and other processing on the WM8741 in PCM hardware mode, the user must ensure the correct value of OSR is set at all times. Table 47 shows the correct settings: PIN NAME DESCRIPTION
22 OSR/DSDR Oversampling Rate Selection
0 = Low rate (32/44.1/48kHz) Z = Medium rate (88.2/96kHz) 1 = High rate (176.4/192kHz) Table 47 OSR/DSDR Hardware Control Pin Function MUTE PIN A soft mute can be applied to the WM8741 in the digital domain in all PCM. A logic low on the MUTEB pin will cause the attenuation to ramp to infi nite attenuation at a rate of 1022x(4/fs). Setting MUTEB high will return the signal gain to its pr evious value. Figure 26 shows the soft mute characteristic. In DSD Direct mode the MUTEB pin controls the analogue mute in the DAC. This analogue mute is a ‘hard’ mute and is applied and released as soon as the MUTEB pin is toggled. PIN NAME DESCRIPTION
25 MUTEB/
0 = Mute on (no output) 1 = Mute off (normal operation Table 48 MUTEB Hardware Control Pin Function Time (s) Figure 26 Hardware Control Mode Soft Mute Characteristic
w PD, Rev 4.3, February 2013 ZERO FLAG In hardware control mode the ZFLAG pin asserts when 1024 consecutive zero samples are applied to the left and right channels of the WM8741 when in PCM mode. In DSD mode, the ZFLAG has no function. In hardware mode there is no access to the infinite zero detect and so there is no automute function. If this functionality is required, software mode must be used. Figure 27 shows the MUTEB and ZFLAG configuration. Figure 27 Hardware Control Mode MUTEB and ZFLAG Configuration DE-EMPHASIS CONTROL AND ANTI-CLIPPING MODE In hardware control mode, de-emphasis is supported with a maximum error of +1.5dB at a sampling rate of 44.1kHz. Audio material is regularly recorded up to 0dB le vel and heavily compressed. This causes clipping and distortion when the digital media is applied to a DA C. In order to prevent this in the WM8741, an anti-clipping mode is provided, whic h attenuates the digital signal by 2dB as it is processed through the digital filters. Under hardware control de-emphasis and the anti-c lipping mode are only ava ilable when using PCM mode. PIN NAME DESCRIPTION
26 SDIN/
0 = De-emphasis off 1 = De-emphasis on Z = Digital filter anti-clipping mode Table 49 DEEMPH Hardware Control Pin Function
w PD, Rev 4.3, February 2013 DIGITAL FILTER SELECTION The WM8741 includes a wide range of digital filters. A limited set of these can be selected in hardware control mode as listed in Table 50. Full details of each digital filter response can be found in section PCM Digital Filter Selection, from page 37. PIN NAME DESCRIPTION
4 FSEL/
(32/44.1/48kHz): 0 = Response 1 1 = Response 5 Z = Response 4 Digital filter selection (88.2/96kHz and 176.4/192kHz): 0 = Response 1 1 = Response 3 Z = Response 2 Table 50 FSEL/DINR Hardware Control Pin Function There is no choice of digital filters in DSD Direct mode – only the very minimal filtering described in Figure 72 and Figure 73 is available. DIFFERENTIAL MONO MODE If DIFFHW (pin 6) is held to Logic 1, hardware cont rolled differential mono mode is selected. This overrides any other control pin or register bit. Differential mono mode allows the user to build a dual differential stereo DAC implementation with higher performance and differential output. DIFFHW is used in conjunction with MODE/LRSEL (pin 24) to define a ‘left’ or ‘right’ DAC as shown in Table 51. PIN NUMBER 6 24 DESCRIPTION NAME DIFFHW MODE/LRSEL 0 0 Hardware control (stereo)
0 Z 2-wire Software Control
0 1 3-wire software control) 1 0 Mono Left – differential outputs VOUTLP = left channel VOUTLN = left channel inverted VOUTRP = left channel inverted VOUTRN = left channel 1 1 Mono right – differential outputs VOUTLP = right channel inverted VOUTLN = right channel VOUTRP = right channel VOUTRN = right channel inverted Table 51 DIFFHW and MODE/LRSEL Hardware Control Pin Functions Differential mono mode is available for all PCM hardware controlled modes and DSD Direct hardware mode.
w PD, Rev 4.3, February 2013 OVERVIEW OF FUNCTIONS The WM8741 has many modes of operation, and certain restrictions on what f unctions are available in which modes. Table 52 gives an overview of the functions available in hardware and software control modes across all modes of operation: SOFTWARE MODE HARDWARE MODE FUNCTION NORMAL PCM 8FS MODE DSD PLUS DSD DIRECT NORMAL PCM DSD DIRECT Selectable Digital Filters 5 4 4 3 De-emphasis Support Adjustable DSP Dither Differential Mono Mode Zero Detect (ZFLAG) Anti-Clipping Mode Digital Attenuation Audio Interface Daisy Chain 3-wire Software Interface Table 52 Comparison of Functions Available across Operating Modes = function available = function not available
w PD, Rev 4.3, February 2013 REGISTER MAP Reg Name Addr Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default DACLLSB Attenuation 00h 0 0 0 UPDATELL LAT[4:0] 0x000 DACLMSB Attenuation 01h 0 0 0 UPDATELM LAT[9:5] 0x000 DACRLSB Attenuation 02h 0 0 0 UPDATERL RAT[4:0] 0x000 DACRMSB Attenuation 03h 0 0 0 UPDATERM RAT[9:5] 0x000
4 Volume Control 04h 0 AMUTE ZEROFLR[1:0] IZD
ATC ATT2DB VOL_RAMP 0x000
5 Format Control 05h 0 PWDN REV BCP LRP FMT[1:0] IWL[1:0] 0x00A
6 Filter Control 06h 0 ZFLAG_HI DEEMPH[1:0] DSDFILT[1:0] FIRSEL[2:0] 0x000
7 Mode Control 1 07h 0 MODE8X OSR[1:0] SR[2:0] MODESEL[1:0] 0x000
8 Mode Control 2 08h 0 0 DSD_GAIN SDOUT DOUT DIFF[1:0] DITHER[1:0] 0x002
9 Software Reset 09h RESET 0x000
20h 0 0 0 0 0 0 0 DSD_LEVEL DSD_NO_ NOTCH 0x000
w PD, Rev 4.3, February 2013 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION DACLLSB Attenuation 00h [4:0] LAT[4:0] 00 (0dB) LSBs of attenuation data for left channel in 0.125dB steps. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for left channel. 0 = Store LAT[4:0] value but don’t update 1 = Store LAT[4:0] and update attenuation on registers 0-3 Table 53 R0 DACL LSB Attenuation Control Register REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION DACLMSB Attenuation 01h [4:0] LAT[9:5] 00 (0dB) MSBs of attenuation data for left channel in 4dB steps. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for left channel. 0 = Store LAT[9:5] value but don’t update 1 = Store LAT[9:5] and update attenuation on registers 0-3 Table 54 R1 DACL MSB Attenuation Control Register REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION DACRLSB Attenuation 02h [4:0] RAT[4:0] 00 (0dB) LSBs of attenuation data for right channel in 0.125dB steps. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for right channel. 0 = Store RAT[4:0] value but don’t update 1 = Store RAT[4:0] and update attenuation on registers 0-3 Table 55 R2 DACR LSB Attenuation Control Register REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION DACRMSB Attenuation 03h [4:0] RAT[9:5] 00 (0dB) MSBs of attenuation data for right channel in 4dB step. See Table 25 for details. 5 UPDATE 0 Attenuation data load control for right channel. 0 = Store RAT[9:5] value but don’t update 1 = Store RAT[9:5] and update attenuation on registers 0-3 Table 56 R3 DACR MSB Attenuation Control Register
w PD, Rev 4.3, February 2013 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION Volume Control 04h
0 VOL_RAMP 0 Ramps volume from existing attenuation setting to new setting when
UPDATE applied. 0: Step volume change 1: Ramp volume change 1 ATT2DB 0 Anti-clipping mode control. Attenuates PCM gain path by 2 dB: 0: 0dB gain 1: -2dB gain 0 = Right channels use Right attenuation 1 = Right Channels use Left Attenuation 0: Normal Operation 1: Soft mute both channels
4 IZD 0 Enables infinite zero detect (detects 1024 zeros on input):
0 = Disable infinite zero detect 1 = Enable infinite zero detect 6:5 ZEROFLR [1:0] 00 = Pin assigned to logical AND of LEFT and RIGHT channels 01 = Pin assigned to LEFT channel 10 = Pin assigned to RIGHT channel 11 = ZFLAG disabled
7 AMUTE 0 Applies analogue mute in DSD mode
0 = Normal operation 1 = Analogue mute applied Table 57 R4 Volume Control Register
w PD, Rev 4.3, February 2013 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION Format Control 05h [1:0] IWL[1:0] 10 Audio interface input word length. 00 = 16-bit 01 = 20-bit 10 = 24-bit 11 = 32-bit [3:2] FMT[1:0] 10 Audio data format select. 00 = right justified mode 01 = left justified mode 10 = I2S mode 11 = DSP mode 4 LRP 0 Polarity select for LRCLK/DSP mode select. 0 = normal LRCLK polarity/DSP mode A 1 = inverted LRCLK polarity/DSP mode B 0 = normal polarity 1 = inverted polarity 0 = Normal 1 = Inverted 0 = Normal Mode 1 = Power Down Mode Table 58 R5 Format Control Register REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION Filter Control 06h [2:0] FIRSEL 000 Select advanced digital filter response: 000 = Response 1 001 = Response 2 010 = Response 3 011 = Response 4 100 = Response 5 [4:3] DSDFILT 00 Select DSD compensation filter response: 00 = Response 1 01 = Response 2 10 = Response 3 11 = Response 4 [6:5] DEEMPH [1:0] 00 = De-emphasis Off 01 = De-emphasis 32kHz 10 = De-emphasis 44.1kHz 11 = De-emphasis 48kHz 0 = Normal operation 1 = Output Logic 1 Table 59 R6 Filter Control Register
w PD, Rev 4.3, February 2013 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION Mode Control 1 07h [1:0] MODESEL [1:0] 00 DSD/PCM mode select. 00 = PCM mode 01 = DSD Direct mode 10 = DSD Plus mode 11 = Unused [4:2] SR[3:0] 000 MCLK to LRCLK sampling rate ratio control: 000 = auto detect sample rate 001 = 128fs 010 = 192fs 011 = 256fs 100 = 384fs 101 = 512fs 110 = 768fs [6:5] OSR[1:0] 00 Selects low, medium or high sample rate mode for filter selection (equivalent to OSR pin functionality in Hardware Mode) 00 = Low rate (32/44.1/48kHz) 01 = Medium rate (96kHz) 10 = High rate (192kHz) 11 = Unused 0 = Normal operation 1 = 8FS mode (digital filters bypassed) Table 60 R7 Mode Control Register 1 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION Mode Control 2 08h [1:0] DITHER[1:0] 10 ALU dither mode select: 00 = dither off 01 = RPDF dither applied in ALU 10 = TPDF dither applied in ALU 11 = HPDF dither applied in ALU Note: DITHER[1:0] applies only to the dither mode in the ALU.
w PD, Rev 4.3, February 2013 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION [3:2] DIFF[1:0] 00 00 = Stereo 10 = Stereo reverse (left and right channels swapped) 01 = Mono left – differential outputs VOUTLP is left channel. VOUTLN is left channel inverted. VOUTRP is left channel inverted. VOUTRN is left channel. 11 = Mono right – differential outputs. VOUTLP is right channel inverted. VOUTLN is right channel. VOUTRP is right channel. VOUTRN is right channel inverted. 4 DOUT 0 Daisychaining Mode. Audio data output control: 0 = No audio data daisychaining 1 = Audio data output on pin 23 5 SDOUT 0 Daisychaining Mode. Control data output control: 0 = No control data daisychaining 1 = Control data output on pin 25
6 DSD_GAIN 0 DSD Plus gain control:
0 = Low gain, 1.4Vrms differential output level 1 = High gain, 2.0Vrms differential output level Table 61 R8 Mode Control Register 2 REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION Software reset 09h [7:0] RESET 00000000 Software reset. Writing to the register resets the entire chip, including the register map. Table 62 R9 Software Reset Control Register REGISTER ADDRESS BITS NAME DEFAULT DESCRIPTION R32 Additional Control 1 20h 0: Enable 8fs notch filter 1: Disable 8fs notch filter
1 DSD_LEVEL 1 DSD Direct Filter Gain
0: High Gain 1: Low Gain Table 63 R32 Additional Control 1
w PD, Rev 4.3, February 2013 DIGITAL FILTER CHARACTERISTICS PCM MODE FILTER CHARACTERISTICS PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Low Rate (32/44.1/48kHz) PCM Filter Response 1 Passband 0.000057dB 0.454fs Passband Ripple 0.000057 dB Stopband 0.546fs Stopband Attenuation -111.8 dB Attenuation at fs/2 -6.02 dB Group Delay 43 fs Low Rate (32/44.1/48kHz) PCM Filter Response 2 Passband 0.000036 dB 0.408fs Passband Ripple 0.000036 dB Stopband 0.522fs Stopband Attenuation -111.1 dB Attenuation at fs/2 Fs/2 -28.07 dB Group Delay 8 fs Low Rate (32/44.1/48kHz) PCM Filter Response 3 Passband 0.000058 dB 0.454fs Passband Ripple 0.000058 dB Stopband 0.546fs Stopband Attenuation -110.3 dB Attenuation at fs/2 Fs/2 -6.43 dB Group Delay 7 fs Low Rate (32/44.1/48kHz) PCM Filter Response 4 Passband 0.000066 dB 0.417fs Passband Ripple 0.000066 dB Stopband 0.500fs Stopband Attenuation -110.4 dB Attenuation at fs/2 Fs/2 -116.19 dB Group Delay 47 fs Low Rate (32/44.1/48kHz) PCM Filter Response 5 Passband 0.000041 dB 0.417fs Passband Ripple 0.000041 dB Stopband 0.500fs Stopband Attenuation -111.8 dB Attenuation at fs/2 Fs/2 -112.45 dB Group Delay 8 fs Table 64 Low Rate PCM Filter Characteristics
w PD, Rev 4.3, February 2013 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Medium Rate (88.2/96kHz) PCM Filter Response 1 Passband 0.000021 dB 0.208fs Passband Ripple 0.000021 dB Stopband 0.500fs Stopband Attenuation -120.3 dB Attenuation at fs/2 Fs/2 -120.41 dB Group Delay 17 fs Medium Rate (88.2/96kHz) PCM Filter Response 2 Passband 0.000014 dB 0.208fs Passband Ripple 0.000014 dB Stopband 0.500fs Stopband Attenuation -120.8 dB Attenuation at fs/2 Fs/2 -127.96 dB Group Delay 9 fs Medium Rate (88.2/96kHz) PCM Filter Response 3 Passband 0.000048 dB 0.417fs Passband Ripple 0.000048 dB Stopband 0.500fs Stopband Attenuation -115.5 dB Attenuation at fs/2 Fs/2 -116.89 dB Group Delay 48 fs Medium Rate (88.2/96kHz) PCM Filter Response 4 Passband 0.000021 dB 0.208fs Passband Ripple 0.000021 dB Stopband 0.458fs Stopband Attenuation -120.0 dB Attenuation at fs/2 Fs/2 -126.82 dB Group Delay 9 fs Medium Rate (88.2/96kHz) PCM Filter Response 5 Passband 0.000023 dB 0.208fs Passband Ripple 0.000023 dB Stopband 0.458fs Stopband Attenuation -122.5 dB Attenuation at fs/2 Fs/2 -130.52 dB Group Delay 8 fs Table 65 Medium Rate PCM Filter Characteristics
w PD, Rev 4.3, February 2013 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT High Rate (176.4/192kHz) PCM Filter Response 1 Passband 0.000010 dB 0.104fs Passband Ripple 0.000010 dB Stopband 0.500fs Stopband Attenuation -120.0 dB Attenuation at fs/2 Fs/2 -127.5 dB Group Delay 10 fs High Rate (176.4/192kHz) PCM Filter Response 2 Passband 0.000031 dB 0.104fs Passband Ripple 0.000031 dB Stopband 0.500fs Stopband Attenuation -120.0 dB Attenuation at fs/2 Fs/2 -124.93 dB Group Delay 4 fs High Rate (176.4/192kHz) PCM Filter Response 3 Passband 0.000873 dB 0.400fs Passband Ripple 0.000873 dB Stopband 0.500fs Stopband Attenuation -110.1 dB Attenuation at fs/2 Fs/2 -112.67 dB Group Delay 31 fs High Rate (176.4/192kHz) PCM Filter Response 4 Passband 0.000015 dB 0.104fs Passband Ripple 0.000015 dB Stopband 0.400fs Stopband Attenuation -120.0 dB Attenuation at fs/2 Fs/2 -120.58 dB Group Delay 6 fs High Rate (176.4/192kHz) PCM Filter Response 5 Passband 0.000001 dB 0.104fs Passband Ripple 0.000001 dB Stopband 0.400fs Stopband Attenuation -122.8 dB Attenuation at fs/2 Fs/2 -128.58 dB Group Delay 18 fs Table 66 High Rate PCM Filter Characteristics 8FS MODE FILTER CHARACTERISTICS PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 8FS Mode Filter Passband 0.000021 dB 0.455 fs Passband Ripple 0.000021 dB Filter Cut-off -3dB point 121.13 kHz Group Delay 5 fs Table 67 8FS Mode Filter Characteristics
w PD, Rev 4.3, February 2013 DSD PLUS MODE FILTER CHARACTERISTICS PARAMETER TEST CONDITIONS MIN TYP MAX UNIT DSD Plus Filter Response 1 Passband 0.020423 dB 22.48 kHz Passband Ripple 0.020423 dB Stopband 127.69 kHz Stopband Attenuation -38.51 dB Filter Cut-off -3dB point 58.91 kHz Group Delay 71 fs DSD Plus Filter Response 2 Passband 0.011308dB 23.04 kHz Passband Ripple 0.011308 dB Stopband 120.41 kHz Stopband Attenuation -44.52 dB Filter Cut-off -3dB point 49.83 kHz Group Delay 127 fs DSD Plus Filter Response 3 Passband 0.019762 dB 27.35 kHz Passband Ripple 0.019762 dB Stopband 70.14 kHz Stopband Attenuation -26.28 dB Filter Cut-off -3dB point 49.74 kHz Group Delay 46 Fs DSD Plus Filter Response 4 Passband 0.004140 dB 20.24 kHz Passband Ripple 0.004140 dB Stopband 70.03 kHz Stopband Attenuation -48.05 dB Filter Cut-off -3dB point 49.78 kHz Group Delay 127 fs Table 68 DSD Plus Filter Characteristics
w PD, Rev 4.3, February 2013 PACKAGE DIMENSIONS 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. DM007.EDS: 28 PIN SSOP (10.2 x 5.3 x 1.75 mm) Symbols Dimensions (mm) MIN NOM MAX A ----- ----- 2.0 A1 0.05 ----- 0.25 A2 1.65 1.75 1.85 b 0.22 0.30 0.38 c 0.09 ----- 0.25 D 9.90 10.20 10.50 e E 7.40 7.80 8.20 5.00 5.30 5.60 L 0.55 0.75 0.95 A A2 A1 141 1528 E1 E c L GAUGE PLANE 0.25 eb D SEATING PLANE -C- 0.10 C REF: JEDEC.95, MO-150 L1 1.25 REF
0.65 BSC
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w PD, Rev 4.3, February 2013
REVISION HISTORY
DATE REV DESCRIPTION OF CHANGES CHANGED BY 11/02/13 4.3 Operating temp changed from -40 o C to +85 o C to 0 o C to +70 o C JMacD