WM8711

WM8711 Internet Audio DAC with Integrated Headphone Driver Product Preview, Novembert 2000, 1.2 DESCRIPTION The WM8711 is a low power stereo DAC with an integrated headphone driver. The WM8711 is designed specifically for portable MP3 audio and speech players. The WM8711 is also ideal for MD, CD machines and DAT players. Stereo 24-bit multi-bit sigma delta DACs are used with oversampling digital interpolation filters. Digital audio input word lengths from 16-32 bits and sampling rates from 8KHz to 96KHz are supported. Stereo audio outputs are buffered for driving headphones from a programmable volume control, line level outputs are also provided along with anti-thump mute and power up/down circuitry. The device is controlled via a 2 or 3 wire serial interface. The interface provides access to all features including volume controls, mutes, de-emphasis and extensive power management facilities. The device is available in a small 28pin SSOP package. A USB mode is provided where all audio rates can be derived from a single 12MHz MCLK, saving on the need for a PLL or multiple crystals. FEATURES • Audio Performance - 100dB SNR (‘A’ weighted @ 48kHz) DAC - 1.42 – 3.6V Digital Supply Operation - 2.7 – 3.6V Analogue Supply Operation DAC Sampling Frequency: 8KHz – 96KHz 2 or 3-Wire MPU Serial Control Interface Programmable Audio Data Interface Modes - I2S, Left, Right Justified or DSP - 16/20/24/32 bit Word Lengths - Master or Slave Clocking Mode Stereo Audio Outputs Output Volume and Mute Controls Highly Efficient Headphone Driver Playback Mode Power Consumption < 18mW 28-Pin SSOP Package • • • • • • • • APPLICATIONS • • Portable MP3 Players CD and Minidisc Players BLOCK DIAGRAM MODE AGND (15) AVDD SCLK VMID (16) SDIN CSB (22) (23) (24) (21) (14) (8) HPVDD CONTROL INTERFACE WM8711 (11) HPGND (19) RLINEIN MUTE VOL/ MUTE DIGTAL AUDIO INTERFACE H/P DRIVER (10) RHPOUT DAC DACDAT (4) DACLRC (5) Σ +6 to -73dB 1 dB Steps (13) ROUT DIGITAL FILTERS (12) LOUT DAC BCLK (3) Σ MUTE +6 to -73dB 1 dB Steps VOL/ MUTE H/P DRIVER (9) LHPOUT OSC CLKIN DIVIDER (Div x1, x2) CLKIN DIVIDER (Div x1, x2) (20) LLINEIN (26) XTO (25) XTI/MCLK (2) CLKOUT (27) DCVDD (1.5V) (1) DBVDD (3.3V) (28) DGND WOLFSON MICROELECTRONICS LTD Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK Tel: +44 (0) 131 667 9386 Fax: +44 (0) 131 667 5176 Email: sales@wolfson.co.uk http://www.wolfson.co.uk Product Preview data sheets contain specifications for products in the formative phase of development. These products may be changed or discontinued without notice. 2000 Wolfson Microelectronics Ltd. WM8711 PIN CONFIGURATION DBVDD CLKOUT BCLK DACDAT DACLRC NC NC HPVDD LHPOUT RHPOUT HPGND LOUT ROUT AVDD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 DGND DCVDD XTO XTI/MCLK SCLK SDIN CSB MODE LLINEIN RLINEIN NC NC VMID AGND Product Preview ORDERING INFORMATION DEVICE XWM8711EDS TEMP. RANGE -10 to +70oC PACKAGE 28-pin SSOP PIN DESCRIPTION PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Note: 1. Pull Up/Down only present when Control Register Interface ACTIVE=0 to conserve power. RLINEIN LLINEIN MODE CSB SDIN SCLK XTI/MCLK XTO DCVDD DGND HPVDD LHPOUT RHPOUT HPGND LOUT ROUT AVDD AGND VMID NAME DBVDD CLKOUT BCLK DACDAT DACLRC TYPE Supply Digital Output Digital Input/Output Digital Input Digital Input/Output NC NC Supply Analogue Output Analogue Output Ground Analogue Output Analogue Output Supply Ground Analogue Output NC NC Analogue Input Analogue Input Digital Input Digital Input Digital Input Digital Input Digital Input Digital Output Supply Ground Digital Buffers VDD Buffered Clock Output Digital Audio Bit Clock, Pull Down (see Note 1) DAC Digital Audio Data Input DAC Sample Rate Left/Right Clock, Pull Down (see Note 1) No Connection No Connection Headphone VDD Left Channel Headphone Output Right Channel Headphone Output Headphone GND Left Channel Line Output Right Channel Line Output Analogue VDD Analogue GND Mid-rail reference decoupling point No Connection No Connection Right Channel Line Input (AC coupled) Left Channel Line Input (AC coupled) Control Interface Selection, Pull up (see Note 1) 3-Wire MPU Chip Select/ 2-Wire MPU interface address selection, active low, Pull up (see Note 1) 3-Wire MPU Data Input / 2-Wire MPU Data Input 3-Wire MPU Clock Input / 2-Wire MPU Clock Input Crystal Input or Master Clock Input (MCLK) Crystal Output Digital Core VDD Digital GND DESCRIPTION WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 2 WM8711 ABSOLUTE MAXIMUM RATINGS Product Preview 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. CONDITION Digital supply voltage Analogue supply voltage Voltage range digital inputs Voltage range analogue inputs Master Clock Frequency (see Note 4) Operating temperature range, TA Storage temperature Package body temperature (soldering 10 seconds) Package body temperature (soldering 2 minutes) Notes: 1. 2. 3. 4. Analogue and digital grounds must always be within 0.3V of each other. MIN -0.3V -0.3V DGND -0.3V AGND -0.3V -10°C -65°C MAX +3.63V +3.63V DVDD +0.3V AVDD +0.3V 40MHz +70°C +150°C +240°C +183°C The digital supply core voltage (DCVDD) must always be less than or equal to the analogue supply voltage (AVDD) or digital supply buffer voltage (DBVDD). The digital supply buffer voltage (DBVDD) must always be less than or equal to the analogue supply voltage (AVDD). When CLKIDIV2 = 1. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 3 WM8711 RECOMMENDED OPERATING CONDITIONS PARAMETER Digital supply range (Core) Digital supply range (Buffer) Analogue supply range Ground Total analogue supply current Digital supply current Standby Current Consumption SYMBOL DCVDD DBVDD AVDD, HPVDD DGND,AGND,HPGND IAVDD, IHPVDD IDCVDD, IDBVDD DCVDD, DBVDD, AVDD, HPVDD= 3.3V DCVDD, DBVDD, AVDD, HPVDD= 3.3V TEST CONDITIONS MIN 1.42 2.7 2.7 0 8 3 10 TYP Product Preview MAX 3.6 3.6 3.6 UNIT V V V V mA mA uA ELECTRICAL CHARACTERISTICS Test Conditions AVDD, HPVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER Input LOW level Input HIGH level Output LOW Output HIGH Power On Reset Threshold (DCVDD) DCVDD Threshold On -> Off Hysteresis DCVDD Threshold Off -> On Analogue Reference Levels Reference voltage Potential divider resistance 0dBFs Full scale output voltage SNR (Note 1,2) SNR (Note 1,2) SNR (Note 1,2) VVMID RVMID At LINE outputs A-weighted, @ fs = 48KHz A-weighted @ fs = 96KHz A-weighted, @ fs = 48KHz, AVDD = 2.7V DNR A-weighted, -60dB full scale input 1KHz, 0dBFs 1kHz, -3dBFs Power Supply Rejection Ratio PSSR 1kHz 100mVpp 20Hz to 20kHz 100mVpp DAC channel separation 85 90 AVDD/2 – 50mV 40K AVDD/2 50K 1.0 x AVDD/3.3 100 98 93 AVDD/2 + 50mV 60K V Ohms Vrms dB dB dB Vth VIH VOL 0.7 0.9 0.3 0.6 1.2 V V V SYMBOL VIL VIH VOL VOH .9 x DBVDD .7 x DBVDD 0.10 x DBVDD TEST CONDITIONS MIN TYP MAX .3 x DBVDD UNIT V V V V Digital Logic Levels (CMOS Levels) Line Output for DAC Playback Only (Load = 10K ohms. 50pF) Dynamic Range (Note 2) THD 90 -88 -92 50 45 100 -80 -86 dB dB dB dB dB dB WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 4 WM8711 Product Preview Test Conditions AVDD, HPVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER Stereo Headphone Output 0dB Full scale output voltage Max Output Power RL = 32 ohms Max Output Power RL = 16 ohms SNR (Note 1,2) THD PO PO A-weighted 1kHz, RL = 32 ohms @ PO = 10mW rms 1kHz, RL = 32 ohms @ PO = 20mW rms Power Supply Rejection Ratio PSSR 1kHz 100mVpp 20Hz to 20kHz 100mVpp Programmable Gain Maximum Programmable Gain Minimum Programmable Gain Step Size Mute attenuation Notes: 1. 2. Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured ‘A’ weighted over a 20Hz to 20kHz bandwidth. All performance measurements done with 20kHz low pass filter, 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. VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance). 1kHz 1kHz 1kHz, 0dB 90 1.0 x AVDD/3.3 30 40 97 0.1 60 1.0 40 50 45 6 -73 1 80 0.1 60 1.0 40 Vrms mW mW dB % dB % dB dB dB dB dB dB SYMBOL TEST CONDITIONS MIN TYP MAX UNIT 3. 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 no 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. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 5 WM8711 POWER CONSUMPTION OSCPD OUTPD DACPD MODE DESCRIPTION POWEROFF CLKOUTPD CURRENT CONSUMPTION Product Preview MIN Playback Playback Oscillator and CLKOUT disabled Standby Power Down 0 0 0 1 0 1 1 X 0 1 1 X 0 0 1 X 0 0 1 1 TYP 7 6 0.05 0.01 MAX UNITS mA mA mA mA Table 1 Powerdown Mode Current Consumption Examples Notes: 1. 2. 3. AVDD, HPVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC. Slave Mode, fs = 48kHz, MCLK = 256fs (12.288MHz). All figures are quiescent, with no signal. The power dissipation in the headphone itself not included in the above table. MASTER CLOCK TIMING tXTIL MCLK tXTIH tXTIY Figure 1 System Clock Timing Requirements Test Conditions AVDD, HPVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, Slave Mode fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER System Clock Timing Information MCLK System clock pulse width high MCLK System clock pulse width low MCLK System clock cycle time MCLK Duty cycle SYMBOL TXTIH TXTIL TXTIY TEST CONDITIONS MIN 18 18 54 40:60 TYP MAX UNIT ns ns ns 60:40 WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 6 WM8711 DIGITAL AUDIO INTERFACE – MASTER MODE Product Preview BCLK (Output) tDL DACLRC (Output) tDLT DACDAT tDHT Figure 2 Digital Audio Data Timing - Master Mode Test Conditions AVDD, HPVDD, DVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, XTI/MCLK = 256fs unless otherwise stated. PARAMETER DACLRC propagation delay from BCLK falling edge DACDAT setup time to BCLCK rising edge DACDAT hold time from BCLK rising edge SYMBOL tDL tDST tDHT TEST CONDITIONS MIN 0 10 10 TYP MAX 10 UNIT ns ns ns Audio Data Input Timing Information DIGITAL AUDIO INTERFACE – SLAVE MODE tBCH BCLK (Input) tBCL tBCY DACLRC (Input) tDS DACDAT tLRH tLRSU Figure 3 Digital Audio Data Timing – Slave Mode Test Conditions AVDD, HPVDD, DVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, slave mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER BCLK cycle time BCLK pulse width high BCLK pulse width low DACLRC set-up time to BCLK rising edge DACLRC hold time from BCLK rising edge DACDAT set-up time to BCLK rising edge SYMBOL tBCY tBCH tBCL tLRSU tLRH tDS TEST CONDITIONS MIN 50 20 20 10 10 10 TYP MAX UNIT ns ns ns ns ns ns Audio Data Input Timing Information WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 7 WM8711 Test Conditions Product Preview AVDD, HPVDD, DVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, slave mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER DACDAT hold time from BCLK rising edge SYMBOL tDH TEST CONDITIONS MIN 10 TYP MAX UNIT ns MPU INTERFACE TIMING tCSL CSB tSCY tSCH SCLK tSCL tSCS tCSS tCSH SDIN tDSU tDHO LSB Figure 4 Program Register Input Timing - 3-Wire MPU Serial Control Mode Test Conditions AVDD, HPVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SCLK rising edge to CSB 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 CSB pulse width low CSB pulse width high CSB rising to SCLK rising SYMBOL tSCS tSCY tSCL tSCH tDSU tDHO tCSL tCSH tCSS TEST CONDITIONS MIN 60 80 20 20 20 20 20 20 20 TYP MAX UNIT ns ns ns ns ns ns ns ns ns Program Register Input Information WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 8 WM8711 Product Preview t3 SDIN t6 SCLK t1 t10 t7 t2 t5 t4 t3 t8 Figure 5 Program Register Input Timing – 2-Wire MPU Serial Control Mode Test Conditions AVDD, HPVDD, DBVDD = 3.3V, AGND = 0V, DCVDD = 1.5V, DGND = 0V, TA = +25oC, Slave Mode, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SCLK Frequency SCLK Low Pulsewidth SCLK High Pulsewidth Hold Time (Start Condition) Setup Time (Start Condition) Data Setup Time SDIN, SCLK Rise Time SDIN, SCLK Fall Time Setup Time (Stop Condition) Data Hold Time t1 t2 t3 t4 t5 t6 t7 t8 t10 600 900 SYMBOL TEST CONDITIONS MIN 0 600 1.3 600 600 100 300 300 TYP MAX 400 UNIT kHz ns us ns ns ns ns ns ns ns Program Register Input Information WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 9 WM8711 DEVICE DESCRIPTION INTRODUCTION Product Preview The WM8711 is a low power audio DAC designed specifically for portable audio products. Its features, performance and low power consumption make it ideal for portable MP3, CD and mini-disc players. The WM8711 includes line and headphone outputs from the on-board DAC, configurable digital audio interface and a choice of 2 or 3 wire MPU control interface. It is fully compatible and an ideal partner for a range of industry standard microprocessors, controllers and DSPs. The on-board digital to analogue converter (DAC) accepts digital audio from the digital audio interface. Digital filter de-emphasis at 32kHz, 44.1kHz and 48kHz can be applied to the digital data under software control. The DAC employs a high quality multi-bit high-order oversampling architecture to again deliver optimum performance with low power consumption. The DAC outputs and Line Inputs (BYPASS) are available both at line level and through a headphone amplifier capable of efficiently driving low impedance headphones. The headphone output volume is adjustable in the analogue domain over a range of +6dB to –73dB and can be muted. The design of the WM8711 minimises power consumption without compromising performance. It includes the ability to power off selective parts of the circuitry under software control, thus conserving power. Separate power save modes can be configured under software control including a standby and power off mode. Special techniques allow the audio to be muted and the device safely placed into standby, sections of the device powered off, volume levels adjusted without any audible clicks, pops or zipper noises. Therefore standby and power off modes may be used dynamically under software control, whenever playback is not required. The device caters for a number of different sampling rates including industry standard 8kHz, 32kHz, 44.1kHz, 48kHz, 88.2kHz and 96kHz. The WM8711 has two schemes to support the programmable sample rates: Normal industry standard 256/384 fs sampling mode may be used. A special USB mode is included, where all audio sampling rates can be generated from a 12.00MHz USB clock. The digital filters used for playback are optimised for each sampling rate used. The digital audio interface can support a range of audio data formats including I2S, DSP Mode (a burst mode in which frame sync plus 2 data packed words are transmitted), MSB-First, left justified and MSB-First, right justified. The digital audio interface can operate in both master or slave modes. The software control uses either a 2 or 3-wire MPU interface. AUDIO SIGNAL PATH DAC FILTERS The DAC filters perform true 24 bit signal processing to convert the incoming digital audio data from the digital audio interface at the specified sample rate to multi-bit oversampled data for processing by the analogue DAC. Figure 6 illustrates the DAC digital filter path. FROM DIGITAL AUDIO INTERFACE DIGITAL DE_EMPHASIS MUTE DIGITAL INTERPOLATION FILTER TO LINE OUTPUTS DEEMP DACMU Figure 6 DAC Filter Schematic WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 10 WM8711 Product Preview The DAC digital filter can apply digital de-emphasis under software control, as shown in Table 2. The DAC can also perform a soft mute where the audio data is digitally brought to a mute level. This removes any abrupt step changes in the audio that might otherwise result in audible clicks in the audio outputs. REGISTER ADDRESS 0000101 Digital Audio Path Control 2:1 BIT LABEL DEEMP[1:0] 00 DEFAULT DESCRIPTION De-emphasis Control (Digital) 11 = 48KHz 10 = 44.1KHz 01 = 32KHz 00 = Disable DAC Soft Mute Control (Digital) 1 = Enable soft mute 0 = Disable soft mute 3 DACMU 1 Table 2 DAC Software Control DAC The WM8711 employs a multi-bit sigma delta oversampling digital to analogue converter. The scheme for the converter is illustrated in Figure 7. FROM DAC DIGITAL FILTERS TO LINE OUTPUT Figure 7 Multi-Bit Oversampling Sigma Delta Schematic The DAC converts the multi-level digital audio data stream from the DAC digital filters into high quality analogue audio. LINE OUTPUTS The WM8711 provides two low impedance line outputs LLINEOUT and RLINEOUT, suitable for driving typical line loads of impedance 10K and capacitance 50pF. The LLINEOUT and RLINEOUT outputs are only available at a line output level and are not level adjustable in the analogue domain, having a fixed gain of 0dB. The level is fixed such that at the DAC full scale level the output level is Vrms at AVDD = 3.3 volts. Note that the DAC full scale level tracks directly with AVDD. The scheme is shown in Figure 8. The line output includes a low order audio low pass filter for removing out-of band components from the sigma-delta DAC. Therefore no further external filtering is required in most applications. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 11 WM8711 BYPASS FROM LINE INPUTS Product Preview DACSEL FROM DAC LINEOUT VMID TO HEADPHONE AMP Figure 8 Line Output Schematic The line output is muted by either muting the DAC (analogue) or Soft Muting (digital) and disabling the BYPASS path. Refer to the DAC section for more details. Whenever the DAC is muted or the device placed into standby mode the DC voltage is maintained at the line outputs to prevent any audible clicks from being present. The software control for the line outputs is shown in Table 3. REGISTER ADDRESS 0000100 Analogue Audio Path Control BIT 3 LABEL BYPASS DEFAULT 1 DESCRIPTION Bypass Switch 1 = Enable Bypass 0 = Disable Bypass DAC Select 1 = Select DAC 0 = Don’t select DAC 4 DACSEL 0 Table 3 Output Software Control The recommended external components are shown in Figure 9. R2 LINEOUT C1 R1 AGND AGND Figure 9 Line Outputs Application Drawing Recommended values are C1 = 470nF (10V npo type), R1 = 47KOhms, R2 = 100 Ohms C1 forms a DC blocking capacitor to the line outputs. R1 prevents the output voltage from drifting so protecting equipment connected to the line output. R2 forms a de-coupling resistor preventing abnormal loads from disturbing the device. Note that poor choice of dielectric material for C1 can have dramatic effects on the measured signal distortion at the output. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 12 WM8711 HEADPHONE AMPLIFIER Product Preview The WM8711 has a stereo headphone output available on LHPOUT and RHPOUT. The output is designed specifically for driving 16 or 32 ohm headphones with maximum efficiency and low power consumption. The headphone output includes a high quality volume level adjustment and mute function. The scheme of the circuit is shown in Figure 10. FROM DAC VIA LINEOUT HPOUT VMID Figure 10 Headphone Amplifier Schematic LHPOUT and RHPOUT volumes can be independently adjusted under software control using the LHPVOL[6:0] and RHPVOL[6:0] bits respectively of the headphone output control registers. The adjustment is logarithmic with an 80dB range in 1dB steps from +6dB to –73dB. The headphone outputs can be separately muted by writing codes less than 0110000 to LHPVOL[6:0] or RHPVO[6:0]L bits. Whenever the headphone outputs are muted or the device placed into standby mode, the DC voltage is maintained at the line outputs to prevent any audible clicks from being present. A zero cross detect circuit is provided at the input to the headphones under the control of the LZCEN and RZCEN bits of the headphone output control register. Using these controls the volume control values are only updated when the input signal to the gain stage is close to the analogue ground level. This minimises and audible clicks and zipper noise as the gain values are changed or the device muted. Note that this circuit has no time out so if only DC levels are being applied to the gain stage input of more than approximately 20mv, then the gain will not be updated. This zero cross function is enabled when the LZCEN and RZCEN bit is set high during a volume register write. If there is concern that a DC level may have blocked a volume change (one made with LZCEN or RZCEN set high) then a subsequent volume write of the same value, but with the LZCEN or RZCEN bit set low will force a volume update, regardless of the DC level. LHPOUT and RHPOUT volume and zero-cross setting can be changed independently. Alternatively, the user can lock the two channels together, allowing both to be updated simultaneously, halving the number of serial writes required, provided that the same gain is needed for both channels. This is achieved through writing to the HPBOTH bit of the control register. Setting LRHPBOTH whilst writing to LHPVOL and LZCEN will simultaneously update the Right Headphone controls similarly. The corresponding effect on updating RLHPBOTH is also achieved. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 13 WM8711 The software control is given in Table 4. REGISTER ADDRESS 0000010 Left Headphone Out BIT 6:0 LABEL LHPVOL[6:0] DEFAULT 1111001 ( 0dB ) Product Preview DESCRIPTION Left Channel Headphone Output Volume Control 1111111 = +6dB . . 1dB steps down to 0110000 = -73dB 0000000 to 0101111 = MUTE Left Channel Zero Cross detect Enable 1 = Enable 0 = Disable Left to Right Channel Headphone Volume, Mute and Zero Cross Data Load Control 1 = Enable Simultaneous Load of LHPVOL[6:0] and LZCEN to RHPVOL[6:0] and RZCEN 0 = Disable Simultaneous Load Right Channel Headphone Output Volume Control 1111111 = +6dB . . 1dB steps down to 0110000 = -73dB 0000000 to 0101111 = MUTE Right Channel Zero Cross Detect Enable 1 = Enable 0 = Disable Right to Left Channel Headphone Volume, Mute and Zero Cross Data Load Control 1 = Enable Simultaneous Load of RHPVOL[6:0] and RZCEN to LHPVOL[6:0] and LZCEN 0 = Disable Simultaneous Load 7 LZCEN 1 8 LRHPBOTH 0 0000011 Right Headphone Out 6:0 RHPVOL[7:0] 1111001 ( 0dB ) 7 RZCEN 1 8 RLHPBOTH 0 Table 4 Headphone Output Software Control WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 14 WM8711 Product Preview The recommended external components required to complete the application are shown in Figure 11. HPOUT C1 R1 AGND AGND Figure 11 Headphone Output Application Drawing Recommended values are C1 = 220uF (10V electrolytic), R1 = 47KOhms C1 forms a DC blocking capacitor to isolate the dc of the HPOUT from the headphones. R1 form a pull down resistor to discharge C1 to prevent the voltage at the connection to the headphones from rising to a level that may damage the headphones. L1 (optional) forms a phase shifting network with the headphone load aiding overall performance, and increasing the protection of the WM8711 headphone amplifier from potentially destructive externally applied electrostatic discharge events. DEVICE OPERATION DEVICE RESETTING The WM8711 contains a power on reset circuit that resets the internal state of the device to a known condition. The power on reset is applied as DCVDD powers on and released only after the voltage level of DCVDD crosses a minimum turn off threshold. If DCVDD later falls below a minimum turn on threshold voltage then the power on reset is re-applied. The threshold voltages and associated hysteresis are shown in the Electrical Characteristics table. The user also has the ability to reset the device to a known state under software control as shown in the table below. REGISTER ADDRESS 0001111 Reset Register BIT 8:0 LABEL RESET DEFAULT not reset DESCRIPTION Reset Register Writing 00000000 to register resets device Table 5 Software Control of Reset When using the software reset. In 3-wire mode the reset is applied on the rising edge of CSB and released on the next rising edge of SCLK. In 2-wire mode the reset is applied for the duration of the ACK signal (approximately 1 SCLK period, refer to Figure 20). CLOCKING SCHEMES In a typical digital audio system there is only 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. To allow WM8711 to be used in a centrally clocked system, the WM8711 is capable of either generating this system clock itself or receiving it from an external source as will be discussed. For applications where it is desirable that the WM8711 is the system clock source, then clock generation is achieved through the use of a suitable crystal connected between the XTI/MCLK input and XTO output pins (see CRYSTAL OSCILLATOR section). WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 15 WM8711 Product Preview For applications where a component other than the WM8711 will generate the reference clock, the external system Master Clock can be applied directly through the XTI/MCLK input pin with no software configuration necessary. Note that in this situation, the oscillator circuit of the WM8711 can be safely powered down to conserve power (see POWER DOWN section) CORE CLOCK The WM8711 DSP core can be clocked either by MCLK or MCLK divided by 2. This is controlled by software as shown in Table 6 below. REGISTER ADDRESS 0001000 Sampling Control BIT 6 LABEL CLKIDIV2 0 DEFAULT DESCRIPTION Core Clock divider select 1 = Core Clock is MCLK divides by 2 0 = Core Clock is MCLK Table 6 Software Control of Core Clock Having a programmable MCLK divider allows the device to be used in applications where higher frequency master Clocks are available. For example the device can support 512Fs master clocks whilst fundamentally operating in a 256Fs mode. CRYSTAL OSCILLATOR The WM8711 includes a crystal oscillator circuit that allows the audio system’s reference clock to be generated on the device. This is available to the rest of the audio system in buffered form on CLKOUT. The crystal oscillator is a low radiation type, designed for low EMI. A typical application circuit is shown Figure 12. XTI/MCLK XTO Cp Cp DGND DGND Figure 12 Crystal Oscillator Application Circuit For crystal frequencies in the 12MHz range, a Cp of 10pF is recommended. For crystal frequencies in the 18MHz range, 15pF Cp is recommended. The WM8711 crystal oscillator provides an extremely low jitter clock source. Low jitter clocks are a requirement for high quality audio DACs, regardless of the converter architecture. The WM8711 architecture is less susceptible than most converter techniques but still requires clocks with less than approximately 1ns of jitter to maintain performance. In applications where there is more than one source for the master clock, it is recommended that the clock is generated by the WM8711 to minimise such problems. CLOCKOUT The Core Clock is internally buffered and made available externally to the audio system on the CLKOUT output pin. CLKOUT provides a replication of the Core Clock, but buffered as suitable for driving external loads. There is no phase inversion between XTI/MCLK, the Core Clock and CLOCKOUT but there will inevitably be some delay. The delay will be dependent on the load that CLOCKOUT drives. Refer to Electrical Characteristics. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 16 WM8711 Product Preview CLKOUT can also be divided by 2 under software control, refer to Table 7. Note that if CLKOUT is not required then the CLKOUT buffer on the WM8711 can be safely powered down to conserve power (see POWER DOWN section). If the system architect has the choice between using FCLKOUT = FMCLK or FCLKOUT = FMCLK/2 in the interface, the latter is recommended to conserve power. When the divide by two is selected CLKOUT changes on the rising edge of MCLK. Please refer to Electrical Characteristics for timing information. REGISTER ADDRESS 0001000 Sampling Control BIT 7 LABEL CLKODIV2 0 DEFAULT DESCRIPTION CLKOUT divider select 1 = CLOCKOUT is Core Clock divides by 2 0 = CLOCKOUT is Core Clock Table 7 Programming CLKOUT CLKOUT is disabled and set low whenever the device is in reset. DIGITAL AUDIO INTERFACES WM8711 may be operated in either one of the 4 offered audio interface modes. These are: • • • • Right justified Left justified I2S DSP mode All four of these modes are MSB first and operate with data 16 to 32 bits, except in right justified mode where 32 bit data is not supported. The digital audio interface receives the digital audio data for the internal DAC digital filters on the DACDAT input. DACDAT is the formatted digital audio data stream output to the DAC digital filters with left and right channels multiplexed together. DACLRC is an alignment clock that controls whether Left or Right channel data is present on DATDAT. DACDAT and DACLRC are synchronous with the BCLK signal with each data bit transition signified by a BCLK transition. DACDAT is always an input. BCLK and DACLRC are either outputs or inputs depending whether the device is in master or slave mode. Refer to the MASTER/SLAVE OPERATION section There are four digital audio interface formats accommodated by the WM8711. These are shown in the figures below. Refer to the Electrical Characteristic section for timing information. Left Justified mode is where the MSB is available on the first rising edge of BCLK following a DACLRC transition. 1/fs LEFT CHANNEL DACLRC RIGHT CHANNEL BCLK DACDAT 1 2 3 n-2 n-1 n 1 2 3 n-2 n-1 n MSB LSB MSB LSB Figure 13 Left Justified Mode I2S mode is where the MSB is available on the 2nd rising edge of BCLK following a LRCLK transition. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 17 WM8711 1/fs Product Preview LEFT CHANNEL DACLRC RIGHT CHANNEL BCLK 1 BCLK 1 BCLK 3 n-2 n-1 n 1 2 3 n-2 n-1 n DACDAT 1 2 MSB LSB MSB LSB Figure 14 I2S Mode Right Justified mode is where the LSB is available on the rising edge of BCLK preceding a LRCLK transition, yet MSB is still transmitted first. 1/fs LEFT CHANNEL DACLRC RIGHT CHANNEL BCLK DACDAT 1 2 3 n-2 n-1 n 1 2 3 n-2 n-1 n MSB Figure 15 Right Justified Mode LSB MSB LSB DSP mode is where the left channel MSB is available on either the 1st or 2nd rising edge of BCLK (selectable by LRP) following an LRCLK transition high. Right channel data immediately follows left channel data. 1/fs 1 BCLK DACLRC BCLK LEFT CHANNEL DACDAT 1 2 3 n-2 n-1 n 1 2 RIGHT CHANNEL 3 n-2 n-1 n MSB Input Word Length (IWL) LSB Note: Input word length is defined by the IWL register, LRP = 1 Figure 16 DSP Mode WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 18 WM8711 Product Preview In all modes DACLRC must always change on the falling edge of BCLK, refer to Figure 13, Figure 14, Figure 15 and Figure 16. Operating the digital audio interface in DSP mode allows ease of use for supporting the various sample rates and word lengths. The only requirement is that all data is transferred within the correct number of BCLK cycles to suit the chosen word length. In order for the digital audio interface to offer similar support in the three other modes (Left Justified, I2S and Right Justified), the DACLRC and BCLK frequencies, continuity and mark-space ratios need more careful consideration. In Slave mode, DACLRC inputs are not required to have a 50:50 mark-space ratio. BCLK input need not be continuous. It is however required that there are sufficient BCLK cycles for each DACLRC transition to clock the chosen data word length. The non-50:50 requirement on the LRC is of use in some situations such as with a USB 12MHZ clock. Here simply dividing down a 12MHz clock within the DSP to generate LRC and BCLK will not generate the appropriate DACLRC since it will no longer change on the falling edge of BCLK. For example, with 12MHz/32k fs mode there are 375 MCLK per LRC. In these situations DACLRC can be made non 50:50. In Master mode, DACLRC will be output with a 50:50 mark-space ratio with BCLK output at 64fs. The exception is in 96/88.2k mode where BCLK is MCLK and in USB mode where BCLK is always 12MHz. So for example in 12MHz/32k fs mode there are 375 master clocks per LRC period. Therefore the DACLRC output will have a mark space ratio of 187:188. The DAC digital audio interface modes are software configurable as indicated in Table 8. Note that dynamically changing the software format may result in erroneous operation of the interfaces and is therefore not recommended. The length of the digital audio data is programmable at 16/20/24 or 32 bits. Refer to the software control table below. The data is signed 2’s complement. The DAC digital filters process data using 24 bits. If the DAC is programmed to receive 16 or 20 bit data, the WM8711 packs the LSBs with zeros. If the DAC is programmed to receive 32 bit data, then it strips the LSBs. The DAC outputs can be swapped under software control using LRP and LRSWAP as shown in Table 8. Stereo samples are normally generated as a Left/Right sampled pair. LRSWAP reverses the order of that a Left sample goes to the right DAC output and a Right sample goes to the left DAC output. LRP swaps the phasing so that a Right/Left sampled pair is expected and preserves the correct channel phase difference, except in DSP mode, where LRP controls the positioning of the MSB relative to the rising edge of DACLRC. To accommodate system timing requirements the interpretation of BCLK maybe inverted, this is controlled via the software shown in Table 8. This is especially appropriate for DSP mode. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 19 WM8711 REGISTER ADDRESS 0000111 Digital Audio Interface Format BIT 1:0 LABEL FORMAT[1:0] DEFAULT 10 Product Preview DESCRIPTION Audio Data Format Select 11 = DSP Mode, frame sync + 2 data packed words 10 = I2S Format, MSB-First left-1 justified 01 = MSB-First, left justified 00 = MSB-First, right justified Input Audio Data Bit Length Select 11 = 32 bits 10 = 24 bits 01 = 20 bits 00 = 16 bits DACLRC phase control (in left, right or I2S modes) 1 = Right Channel DAC data when DACLRC high 0 = Right Channel DAC data when DACLRC low (opposite phasing in I2S mode) or DSP mode A/B select ( in DSP mode only) 1 = MSB is available on 2nd BCLK rising edge after DACLRC rising edge 0 = MSB is available on 1st BCLK rising edge after DACLRC rising edge DAC Left Right Clock Swap 1 = Right Channel DAC Data Left 0 = Right Channel DAC Data Right Master Slave Mode Control 1 = Enable Master Mode 0 = Enable Slave Mode Bit Clock Invert 1 = Invert BCLK 0 = Don’t invert BCLK 3:2 IWL[1:0] 10 4 LRP 0 5 LRSWAP 0 6 MS 0 7 BCLKINV 0 Table 8 Digital Audio Interface Control Note: If right justified 32 bit mode is selected then the WM8711 defaults to 24 bits. MASTER AND SLAVE MODE OPERATION The WM8711 can be configured as either a master or slave mode device. As a master mode device the WM8711 controls sequencing of the data and clocks on the digital audio interface. As a slave device the WM8711 responds with data to the clocks it receives over the digital audio interface. The mode is set with the MS bit of the control register as shown in Table 9. REGISTER ADDRESS 0000111 Digital Audio Interface Format 6 BIT LABEL MS DEFAULT 0 DESCRIPTION Master Slave Mode Control 1 = Enable Master Mode 0 = Enable Slave Mode Table 9 Programming Master/Slave Modes WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 20 WM8711 Product Preview As a master mode device the WM8711 controls the sequencing of data transfer (DACDAT) and output of clocks (BCLK, DACLRC) over the digital audio interface. It uses the timing generated from the MCLK input as the reference for the clock and data transitions. This is illustrated in Figure 17. DACDAT is always an input to the WM8711 independent of master or slave mode. BCLK DSP DECODER WM8711 DACLRC DAC DACDAT Figure 17 Master Mode As a slave device the WM8711 sequences the data transfer (DACDAT) over the digital audio interface in response to the external applied clocks (BCLK, DACLRC). This is illustrated in Figure 18. BCLK DSP DECODER WM8711 DACLRC DAC DACDAT Figure 18 Slave Mode Note that the WM8711 relies on controlled phase relationships between audio interface BCLK, DACLRC and the master MCLK or CLKOUT. To avoid any timing hazards, refer to the timing section for detailed information. AUDIO DATA SAMPLING RATES The WM8711 provides for two modes of operation (normal and USB) to generate the required DAC sampling rates. Normal and USB modes are programmed under software control according to the table below. In Normal mode, the user controls the sample rate by using an appropriate MCLK frequency and the sample rate control register setting. The WM8711 can support sample rates from 8ks/s up to 96ks/s. In USB mode, the user must use a fixed MLCK frequency of 12MHz to generate sample rates from 8ks/s to 96ks/s. It is called USB mode since the common USB (Universal Serial Bus) clock is at 12MHz and the WM8711 can be directly used within such systems. WM8711 can generate all the normal audio sample rates from this one Master Clock frequency, removing the need for different master clocks or PLL circuits. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 21 WM8711 REGISTER ADDRESS 0001000 Sampling Control BIT 0 LABEL USB/ NORMAL BOSR DEFAULT 0 Product Preview DESCRIPTION Mode Select 1 = USB mode (250/272fs) 0 = Normal mode (256/384fs) Base Over-Sampling Rate USB Mode 0 = 250fs 1 = 272fs Normal Mode 0 = 256fs 1 = 384fs 1 0 5:2 SR[3:0] 0000 DAC sample rate control; See USB Mode and Normal Mode Sample Rate sections for operation Table 10 Sample Rate Control NORMAL MODE SAMPLE RATES In normal mode MCLK is set up according to the desired sample rates of the DAC. For DAC sampling rates of 8, 32, 48 or 96KHz, MCLK frequencies of either 12.288MHz (256Fs) or 18.432MHz (384Fs) can be used. DAC sampling rates of 8, 44.1 or 88.2KHz from MCLK frequencies of either 11.2896MHz (256Fs) or 16.9344MHz (384Fs) can be used. The table below should be used to set up the device to work with the various sample rate combinations. Refer to Digital Filter Characteristics section for an explanation of the different filter types. SAMPLING RATE DAC KHz 48 8 32 96 44.1 8 (Note 1) 88.2 MHz 12.288 18.432 12.288 18.432 12.288 18.432 12.288 18.432 11.2896 16.9344 11.2896 16.9344 11.2896 16.9344 BOSR 0 1 0 1 0 1 0 1 0 1 0 1 0 1 MCLK FREQUENCY SAMPLE RATE REGISTER SETTINGS SR3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 SR2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 SR1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 SR0 0 0 1 1 0 0 1 1 0 0 1 1 1 1 2 1 1 2 1 1 1 DIGITAL FILTER TYPE Table 11 Normal Mode Sample Rate Look-up Table Notes: 1. 2. 8k not exact, actual = 8.018kHz All other combinations of BOSR and SR[3:0] that are not in the truth table are invalid The BOSR bit represents the base over-sampling rate. This is the rate that the WM8711 digital signal processing is carried out at. In Normal mode, with BOSR = 0, the base over-sampling rate is at 256Fs, with BOSR = 1, the base over-sampling rate is at 384Fs. This can be used to determine the actual audio data rate required by the DAC. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 22 WM8711 The exact sample rates achieved are defined by the relationships in Table 12 below. TARGET SAMPLING RATE MCLK=12.288 KHz 8 32 44.1 48 88.2 96 KHz 8 12.288MHz/256 x 1/6 Product Preview ACTUAL SAMPLING RATE BOSR=0 (256FS) MCLK=11.2896 KHz 8.018 11.2896MHz/256 x 2/11 BOSR=1 (384FS) MCLK=18.432 KHz 8 18.432MHz/384 x 1/6 MCLK=16.9344 KHz 8.018 16.9344MHz/384 x 2/11 32 12.288MHz/256 x 2/3 not available 44.1 11.2896MHz/256 32 18.432MHz/384x 2/3 not available 44.1 16.9344MHz /384 not available 48 12.288MHz/256 not available 48 18.432MHz/384 not available 88.2 11.2896MHz/384 x 2 not available 88.2 16.9344MHz /384 x 2 not available 96 12.288MHz/256 x 2 not available 96 18.432MHz/384 x 2 not available not available Table 12 Normal Mode Actual Sample Rates 128/192FS NORMAL MODE The Normal Mode sample rates are designed for standard 256Fs and 384Fs MCLK rates. However the WM8711 is also capable of being clocked from a 128/192Fs MCLK for application over limited sampling rates as shown in the table below. SAMPLING RATE ADC KHz 48 44.1 DAC KHz 48 44.1 MHz 6.144 9.216 5.6448 8.4672 BOSR 0 1 0 1 MCLK FREQUENCY SAMPLE RATE REGISTER SETTINGS SR3 0 0 1 1 SR2 1 1 1 1 SR1 1 1 1 1 SR0 1 1 1 1 2 2 DIGITAL FILTER TYPE Table 13 128/192Fs Normal Mode Sample Rate Look-up Table 512/768FS NORMAL MODE 512 Fs and 768 Fs MCLK rates can be accommodated by using the CLKIDIV2 bit. The core clock to the DSP will be divided by 2 so an external 512/768 MCLK will become 256/384 Fs internally and the device otherwise operates as in Table 10 but with MCLK at twice the specified rate. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 23 WM8711 USB MODE SAMPLE RATES In USB mode the MCLK input is 12MHz only. SAMPLING RATE DAC KHz 48 44.1 (Note 2) 8 8 (Note 1) 32 96 MHz 12.000 12.000 12.000 12.000 12.000 12.000 BOSR 0 1 0 1 0 0 MCLK FREQUENCY SAMPLE RATE REGISTER SETTINGS SR3 0 1 0 1 0 0 SR2 0 0 0 0 1 1 1 SR1 0 0 0 0 1 1 1 SR0 0 0 1 1 0 1 1 Product Preview DIGITAL FILTER TYPE 0 1 0 1 0 3 2 88.2 12.000 1 1 (Note 3) Table 14 USB Mode Sample Rate Look-Up Table Notes: 1. 2. 3. 4. 8k not exact, actual = 8.021kHz 44.1k not exact, actual = 44.118kHz 88.1k not exact, actual = 88.235kHz All other combinations of BOSR and SR[3:0] that are not in the truth table are invalid The BOSR bit represents the base over-sampling rate. This is the rate that the WM8711 digital signal processing is carried out at and the sampling rate will always be a sub-multiple of this. In USB mode, with BOSR = 0, the base over-sampling rate is defined at 250Fs, with BOSR = 1, the base oversampling rate is defined at 272Fs. This can be used to determine the actual audio sampling rate required by the DAC. The exact sample rates supported for all combinations are defined by the relationships in Table 15 below. TARGET SAMPLING RATE KHz 8 32 44.1 48 88.2 96 ACTUAL SAMPLING RATE BOSR=0 ( 250FS) KHz 8 12MHz/(250 x 48/8) BOSR=1 (272FS) KHz 8.021 12MHz/(272 x 11/2) 32 12MHz/(250 x 48/32) not available 44.117 12MHz/272 not available 48 12MHz/250 not available 88.235 12MHz/136 not available 96 12MHz/125 not available Table 15 USB Mode Actual Sample Rates WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 24 WM8711 ACTIVATING DSP AND DIGITAL AUDIO INTERFACE Product Preview To prevent any communication problems from arising across the Digital Audio Interface is disabled (tristate with weak 100k pulldown) at power on. Once the Audio Interface and the Sampling Control has been programmed it is activated by setting the ACTIVE bit under Software Control. REGISTER ADDRESS 0001001 Active Control 0 BIT LABEL ACTIVE 0 DEFAULT DESCRIPTION Activate Interface 1 = Active 0 = Inactive Table 16 Activating DSP and Digital Audio Interface It is recommended that between changing any content of Digital Audio Interface or Sampling Control Register that the active bit is reset then set. SOFTWARE CONTROL INTERFACE The software control interface may be operated using either a 3-wire or 2-wire MPU interface. Selection of interface format is achieved by setting the state of the MODE pin. In 3-wire mode, SDIN is used for the program data, SCLK is used to clock in the program data and CSB is used to latch in the program data. In 2-wire mode, SDIN is used for serial data and SCLK is used for the serial clock. In 2-wire mode, the state of CSB pin allows the user to select one of two addresses. SELECTION OF SERIAL CONTROL MODE The serial control interface may be selected to operate in either 2 or 3-wire modes. This is achieved by setting the state of the MODE pin. MODE 0 1 INTERFACE FORMAT 2 wire 3 wire Table 17 Control Interface Mode Selection 3-WIRE (SPI COMPATIBLE) SERIAL CONTROL MODE The WM8711 can be controlled using a 3-wire serial interface. SDIN is used for the program data, SCLK is used to clock in the program data and CSB is use to latch in the program data. The 3-wire interface protocol is shown in Figure 19. CSB SCLK SDIN B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Figure 19 3-Wire Serial Interface Notes: 1. 2. B[15:9] are Control Address Bits B[8:0] are Control Data Bits 2-WIRE SERIAL CONTROL MODE The WM8711 supports a 2-wire MPU serial interface. The device operates as a slave device only. The WM8711 has one of two slave addresses that are selected by setting the state of pin 10, (CSB). WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 25 WM8711 SDIN SCLK START Figure 20 2-Wire Serial Interface Notes: 1. 2. B[15:9] are Control Address Bits B[8:0] are Control Data Bits CSB STATE (DEFAULT = LOW) 0 1 ADDRESS 0011010 0011011 R ADDR R/W ACK DATA B15-8 ACK DATA B7-0 Product Preview ACK STOP Table 18 2-Wire MPU Interface Address Selection To control the WM8711 on the 2-wire bus the master control device must initiate a data transfer by establishing a start condition, defined by a high to low transition on SDIN while SCLK remains high. This indicates that an address and data transfer will follow. All peripherals on the 2-wire bus respond to the start condition and shift in the next eight bits (7-bit address + R/W bit). The transfer is MSB first. The 7-bit address consists of a 6-bit base address + a single programmable bit to select one of two available addresses for this device (see Table 18). If the correct address is received and the R/W bit is ‘0’, indicating a write, then the WM8711 will respond by pulling SDIN low on the next clock pulse (ACK). The WM8711 is a write only device and will only respond to the R/W bit indicating a write. If the address is not recognised the device will return to the idle condition and wait for a new start condition and valid address. Once the WM8711 has acknowledged a correct address, the controller will send eight data bits (bits B[15]-B[8]). WM8711 will then acknowledge the sent data by pulling SDIN low for one clock pulse. The controller will then send the remaining eight data bits (bits B[7]-B[0]) and the WM8711 will then acknowledge again by pulling SDIN low. A stop condition is defined when there is a low to high transition on SDIN while SCLK is high. If a start or stop condition is detected out of sequence at any point in the data transfer then the device will jump to the idle condition. After receiving a complete address and data sequence the WM8711 returns to the idle state and waits for another start condition. Each write to a register requires the complete sequence of start condition, device address and R/W bit followed by the 16 register address and data bits. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 26 WM8711 POWER DOWN MODES Product Preview The WM8711 contains power conservation modes in which various circuit blocks may be safely powered down in order to conserve power. This is software programmable as shown in the table below. REGISTER ADDRESS 0000110 Power Down Control 0 BIT LABEL LINEINPD DEFAULT 1 DESCRIPTION Line Input Power Down 1 = Enable Power Down 0 = Disable Power Down DAC Power Down 1 = Enable Power Down 0 = Disable Power Down Line Output Power Down 1 = Enable Power Down 0 = Disable Power Down Oscillator Power Down 1 = Enable Power Down 0 = Disable Power Down CLKOUT Power Down 1 = Enable Power Down 0 = Disable Power Down Power Off Device 1 = Device Power Off 0 = Device Power On 3 DACPD 1 4 OUTPD 1 5 OSCPD 0 6 CLKOUTPD 0 7 POWEROFF 1 Table 19 Power Conservation Modes Software Control Note: 1. When writing to register 0000110 bits 1 and 2 should be set to 1. The power down control can be used to either a) permanently disable functions when not required in certain applications or b) to dynamically power up and down functions depending on the operating mode, e.g.: during playback or record. Please follow the special instructions below if dynamic implementations are being used. DACPD: Powers down the DAC and DAC Digital Filters. If this is done dynamically then audible pops will result unless the following guidelines are followed. In order to prevent pops, the DAC should first be soft-muted (DACMU), the output should then be de-selected from the line and headphone output (DACSEL), then the DAC powered down (DACPD). This is of use when the device enters Pause or Stop modes. During DACPD the digital audio interface is remains active. OUTPD: Powers down the Line Headphone Output. If this is done dynamically then audible pops may result unless the DAC is first soft-muted (DACMU). This is of use when the device enters Record, Pause or Stop modes. The device can be put into a standby mode (STANDBY) by powering down all the audio circuitry under software control as shown in Table 20. POWER OFF CLKOUTPD DESCRIPTION OUTPD LINEINPD 1 1 1 STANDBY, but with Crystal Oscillator OS and CLKOUT available STANDBY, but with Crystal Oscillator OS available, CLKOUT not-available STANDBY, Crystal oscillator and CLKOUT notavailable. OSCPD DACPD 1 1 1 0 0 0 0 1 1 0 0 1 1 1 1 Table 20 Standby Mode WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 27 WM8711 Product Preview In STANDBY mode the Control Interface, a small portion of the digital and areas of the analogue circuitry remain active. The active analogue includes the analogue VMID reference so that the analogue line outputs and headphone outputs remain biased to VMID. This reduces any audible effects caused by DC glitches when entering or leaving STANDBY mode. The device can be powered off by writing to the POWEROFF bit of the Power Down register. In POWEROFF mode the Control Interface and a small portion of the digital remain active. The analogue VMID reference is disabled. Refer to Table 21. POWER OFF CLKOUTPD LINEINPD 1 1 X DESCRIPTION OSCPD DACPD OUTPD 1 1 1 0 1 1 0 0 1 X X X 1 1 1 POWEROFF, but with Crystal Oscillator OS and CLKOUT available POWEROFF, but with Crystal Oscillator OS available, CLKOUT not-available POWEROFF, Crystal oscillator and CLKOUT not-available. Table 21 Poweroff Mode REGISTER MAP The complete register map is shown in Table 22. The detailed description can be found in the relevant text of the device description. There are 8 registers with 9 bits per register. These can be controlled using either the 2 wire or 3 wire MPU interface. REGISTER ADDRESS 0000010 Left Headphone Out BIT 6:0 LABEL LHPVOL [6:0] DEFAULT 1111001 ( 0dB ) DESCRIPTION Left Channel Headphone Output Volume Control 1111111 = +6dB . . 1dB steps down to 0110000 = -73dB 0000000 to 0101111 = MUTE Left Channel Zero Cross detect Enable 1 = Enable 0 = Disable Left to Right Channel Headphone Volume, Mute and Zero Cross Data Load Control 1 = Enable Simultaneous Load of LHPVOL[6:0] and LZCEN to RHPVOL[6:0] and RZCEN 0 = Disable Simultaneous Load 7 LZCEN 1 8 LRHPBOTH 0 WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 28 WM8711 REGISTER ADDRESS 0000011 Right Headphone Out BIT 6:0 LABEL RHPVOL [6:0] DEFAULT 1111001 ( 0dB ) Product Preview DESCRIPTION Right Channel Headphone Output Volume Control 1111111 = +6dB . . 1dB steps down to 0110000 = -73dB 0000000 to 0101111 = MUTE Right Channel Zero Cross detect Enable 1 = Enable 0 = Disable Right to Left Channel Headphone Volume, Mute and Zero Cross Data Load Control 1 = Enable Simultaneous Load of RHPVOL[60] and RZCEN to LHPVOL[6:0] and LZCEN 0 = Disable Simultaneous Load Bypass Switch 1 = Enable Bypass 0 = Disable Bypass DAC Select (Analogue) 1 =Select DAC 0 = Don’t select DAC De-emphasis Control (Digital) 11 = 48KHz 10 = 44.1KHz 01 = 32KHz 00 = Disable DAC Soft Mute Control (Digital) 1 = Enable soft mute 0 = Disable soft mute Line Input Power Down 1 = Enable Power Down 0 = Disable Power Down DAC Power Down 1 = Enable Power Down 0 = Disable Power Down Outputs Power Down 1 = Enable Power Down 0 = Disable Power Down Oscillator Power Down 1 = Enable Power Down 0 = Disable Power Down CLKOUT Power Down 1 = Enable Power Down 0 = Disable Power Down POWEROFF mode 1 = Enable POWEROFF 0 = Disable POWEROFF 7 RZCEN 1 8 RLHPBOTH 0 0000100 Audio Path Control 3 BYPASS 1 4 DACSEL 0 0000101 Digital Audio Path Control 2:1 DEEMP[1:0] 00 3 DACMU 1 0000110 Power Down Control 0 LINEINPD 1 3 DACPD 1 4 OUTPD 1 5 OSCPD 0 6 CLKOUTPD 0 7 POWEROFF 1 WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 29 WM8711 REGISTER ADDRESS 0000111 Digital Audio Interface Format BIT 1:0 LABEL FORMAT[1:0] DEFAULT 10 Product Preview DESCRIPTION Audio Data Format Select 11 = DSP Mode, frame sync + 2 data packed words 10 = I2S Format, MSB-First left-1 justified 01 = MSB-First, left justified 00 = MSB-First, right justified Input Audio Data Bit Length Select 11 = 32 bits 10 = 24 bits 01 = 20 bits 00 = 16 bits DACLRC phase control (in left, right or I2S modes) 1 = Right Channel DAC data when DACLRC high 0 = Right Channel DAC data when DACLRC low (opposite phasing in I2S mode) or DSP mode A/B select ( in DSP mode only) 1 = MSB is available on 2nd BCLK rising edge after DACLRC rising edge 0 = MSB is available on 1st BCLK rising edge after DACLRC rising edge DAC Left Right Clock Swap 1 = Right Channel DAC Data Left 0 = Right Channel DAC Data Right Master Slave Mode Control 1 = Enable Master Mode 0 = Enable Slave Mode Bit Clock Invert 1 = Invert BCLK 0 = Don’t invert BCLK Mode Select 1 = USB mode (250/272fs) 0 = Normal mode (256/384fs) Base Over-Sampling Rate USB Mode 0 = 250fs 1 = 272fs 5:2 SR[3:0] 0000 Normal Mode 0 = 256fs 1 = 384fs 3:2 IWL[1:0] 10 4 LRP 0 5 LRSWAP 0 6 MS 0 7 BCLKINV 0 0001000 Sampling Control 0 USB/ NORMAL BOSR 0 1 0 DAC sample rate control; See USB Mode and Normal Mode Sample Rate sections for operation Core Clock divider select 1 = Core Clock is MCLK divide by 2 0 = Core Clock is MCLK CLKOUT divider select 1 = CLOCKOUT is MCLK divide by 2 0 = CLOCKOUT is MCLK 6 CLKIDIV2 0 7 CLKODIV2 0 WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 30 WM8711 REGISTER ADDRESS 0001001 Active Control 0001111 Reset Register 1110000 Test Failsafe 1110001 Analogue Test Register 1 1110010 Analogue Test Register 2 11100011 Digital Test Register 1 11100100 Digital Test Register 2 BIT 0 LABEL ACTIVE DEFAULT 0 Product Preview DESCRIPTION Activate Interface 1 = Active 0 = Inactive Reset Register Writing 00000000 to register resets device Test Mode Failsafe Bit 1 = Test Mode Allowed 0 = Test Mode Locked Out Analogue Test Register 1 8:0 RESET not reset 0 TESTFAIL SAFE ATEST1[8:0] 0 8:0 0 8:0 ATEST2[8:0] 0 Analogue Test Register 2 8:0 DTEST1[8:0] 0 Digital Test Register 1 8:0 DTEST2[8:0] 0 Digital Test Register 2 Table 22 Register Map Description Note: All other bits not explicitly defined in the register table should be set to zero unless specified otherwise (see powerdown section). DIGITAL FILTER CHARACTERISTICS The DAC employ different digital filters. There are 4 types of digital filter, called Type 0, 1, 2 and 3. The performance of Types 0 and 1 is listed in the table below, the responses of all filters is shown in the proceeding pages. PARAMETER Passband Passband Ripple Stopband Stopband Attenuation Passband Passband Ripple Stopband Stopband Attenuation f > 0.5465fs Table 23 Digital Filter Characteristics 0.5465fs -50 dB f > 0.584fs +/- 0.03dB -6dB 0.584fs -50 0 0.5fs +/- 0.03 dB 0.4535fs dB TEST CONDITIONS +/- 0.03dB -6dB MIN 0 0.5fs +/-0.03 dB TYP MAX 0.416fs UNIT DAC Filter Type 0 (USB mode, 250fs operation) DAC Filter Type 1 (USB mode, 272fs or Normal mode operation) WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 31 WM8711 DAC FILTER RESPONSES 0.04 0 0.03 -20 0.02 Response (dB) Product Preview Response (dB) 0.01 0 -0.01 -0.02 -40 -60 -80 -0.03 -100 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 -0.04 0 0.05 0.1 0.15 0.2 0.25 0.3 Frequency (Fs) 0.35 0.4 0.45 0.5 Figure 21 DAC Digital Filter Frequency Response–Type 0 Figure 22 DAC Digital Filter Ripple–Type 0 0.04 0 0.03 -20 0.02 Response (dB) Response (dB) 0.01 0 -0.01 -0.02 -40 -60 -80 -0.03 -100 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 -0.04 0 0.05 0.1 0.15 0.2 0.25 0.3 Frequency (Fs) 0.35 0.4 0.45 0.5 Figure 23 DAC Digital Filter Frequency Response–Type 1 Figure 24 DAC Digital Filter Ripple–Type 1 0.02 0 0.01 -20 0 Response (dB) Response (dB) -0.01 -0.02 -0.03 -0.04 -40 -60 -80 -0.05 -100 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 -0.06 0 0.05 0.1 0.15 Frequency (Fs) 0.2 0.25 Figure 25 DAC Digital Filter Frequency Response–Type 2 Figure 26 DAC Digital Filter Ripple–Type 2 WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 32 WM8711 0 0.05 Product Preview -20 0 Response (dB) -40 Response (dB) -0.05 -0.1 -60 -0.15 -80 -0.2 -100 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 -0.25 0 0.05 0.1 0.15 Frequency (Fs) 0.2 0.25 Figure 27 DAC Digital Filter Frequency Response–Type 3 Figure 28 DAC Digital Filter Ripple–Type 3 DIGITAL DE-EMPHASIS CHARACTERISTICS 0 0.4 0.3 -2 0.2 Response (dB) Response (dB) -4 0.1 0 -0.1 -0.2 -6 -8 -0.3 -10 0 2000 4000 6000 8000 10000 Frequency (Fs) 12000 14000 16000 -0.4 0 2000 4000 6000 8000 10000 Frequency (Fs) 12000 14000 16000 Figure 29 De-Emphasis Frequency Response (32kHz) Figure 30 De-Emphasis Error (32kHz) 0 0.4 0.3 -2 0.2 Response (dB) Response (dB) -4 0.1 0 -0.1 -0.2 -6 -8 -0.3 -10 0 5000 10000 Frequency (Fs) 15000 20000 -0.4 0 5000 10000 Frequency (Fs) 15000 20000 Figure 31 De-Emphasis Frequency Response (44.1kHz) Figure 32 De-Emphasis Error (44.1kHz) WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 33 WM8711 0 0.4 0.3 -2 0.2 Response (dB) Response (dB) Product Preview -4 0.1 0 -0.1 -0.2 -6 -8 -0.3 -10 0 5000 10000 15000 Frequency (Fs) 20000 -0.4 0 5000 10000 15000 Frequency (Fs) 20000 Figure 33 De-Emphasis Frequency Response (48kHz) Figure 34 De-Emphasis Error (48kHz) WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 34 WM8711 RECOMMENDED EXTERNAL COMPONENTS 3.3V 1 Product Preview 3.3V 0.1µF 15 28 DGND AGND 10µF 0.1µF 3.3V 27 + 1.5V - 3.3V 0.1µF 11 5KΩ 5KΩ + 20 LLINEIN HPGND 470nF 47pF + LOUT 5KΩ 5KΩ 12 100Ω 47kΩ + 19 RLINEIN 470nF 470nF 47pF + 5 Audio Serial Data I/F 4 3 DACLRC DACDAT BCLK WM8711 DAC ROUT 13 100Ω 47kΩ 470nF LHPOUT 3.3V 10kΩ 21 22 23 24 9 + 220µF 47kΩ 3-wire Interface 2-wire Interface DGND 3-wire or 2-wire MPU Interface MODE CSB SDIN SCLK RHPOUT 10 + 47kΩ 220µF 2 CLKOUT VMID 100Ω 16 0.1µF + XTI/MCLK XTO 25 26 15pF 15pF Figure 35 External Components Diagram WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 35 + DCVDD HPVDD 8 + 10µF 10µF 10µF 10µF 0.1µF + DBVDD AVDD 14 WM8711 PACKAGE DIMENSIONS DS: 28 PIN SSOP (10.2 x 5.3 x 1.75 mm) Product Preview DM007.C b 28 e 15 E1 E 1 D 14 GAUGE PLANE Θ 0.25 c A A2 A1 L -C0.10 C SEATING PLANE Symbols A A1 A2 b c D e E E1 L θ REF: MIN ----0.05 1.62 0.22 0.09 9.90 7.40 5.00 0.55 o 0 Dimensions (mm) NOM --------1.75 --------10.20 0.65 BSC 7.80 5.30 0.75 o 4 JEDEC.95, MO-150 MAX 2.0 ----1.85 0.38 0.25 10.50 8.20 5.60 0.95 o 8 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. WOLFSON MICROELECTRONICS LTD PP Rev 1.2 November 2000 36