WM8740 Wolfson Microelectronics plc, WM8740 Datasheet
WM8740
Available stocks
Related parts for WM8740
WM8740 Summary of contents
Page 1
... The WM8740 is a very high performance stereo DAC designed for audio applications such as CD, DVD, home theatre systems, set top boxes and digital TV. The WM8740 supports data input word lengths from 16 to 24-bits and sampling rates up to 192kHz. The WM8740 consists of a ...
Page 2
... WM8740 DESCRIPTION ....................................................................................................... 1 FEATURES............................................................................................................. 1 APPLICATIONS ..................................................................................................... 1 BLOCK DIAGRAM ................................................................................................. 1 TABLE OF CONTENTS ......................................................................................... 2 PIN CONFIGURATION ........................................................................................... 3 ORDERING INFORMATION .................................................................................. 3 PIN DESCRIPTION ................................................................................................ 4 ABSOLUTE MAXIMUM RATINGS ......................................................................... 5 RECOMMENDED OPERATING CONDITIONS ..................................................... 6 ELECTRICAL CHARACTERISTICS ...................................................................... 6 INTERNAL POWER ON RESET CIRCUIT ............................................................ 9 DEVICE DESCRIPTION ....................................................................................... 12 SYSTEM CLOCK ........................................................................................................ 12 AUDIO DATA INTERFACE ......................................................................................... 12 NORMAL SAMPLE RATE ........................................................................................... INPUT SAMPLE RATE .................................................................................... 14 MODES OF OPERATION ...
Page 3
... MODE8X 4 SCLK 5 DIFFHW 6 DGND 7 DVDD 8 AVDDR 9 AGNDR 10 VMIDR 11 VOUTRP 12 VOUTRN 13 AGND 14 ORDERING INFORMATION TEMPERATURE DEVICE RANGE WM8740EDS/V -40° to +85°C WM8740SEDS/RV -40° to +85°C Note: Reel Quantity: 2,000 w ML/I2S 28 MC/DM1 27 MD/DM0 26 MUTEB 25 MODE 24 CSBIWO 23 RSTB 22 ZERO 21 AVDDL 20 AGNDL 19 VMIDL 18 VOUTLP 17 VOUTLN ...
Page 4
... WM8740 PIN DESCRIPTION PIN NAME TYPE 1 LRCIN Digital input 2 DIN Digital input 3 BCKIN Digital input 4 MODE8X Digital input 5 SCLK Digital input 6 DIFFHW Digital input 7 DGND Supply 8 DVDD Supply 9 AVDDR Supply 10 AGNDR Supply 11 VMIDR Analogue output 12 VOUTRP Analogue output 13 VOUTRN Analogue output ...
Page 5
... WM8740 PIN NAME TYPE 23 CSBIWO Digital input Internal pull-down 24 MODE Digital input Internal pull-up 25 MUTEB Digital input Internal pull-up 26 MD/DM0 Digital input Internal pull-up 27 MC/DM1 Digital input Internal pull-up 28 ML/I2S Digital input Internal pull-up Note: Digital input pins have Schmitt trigger input buffers. ...
Page 6
... WM8740 RECOMMENDED OPERATING CONDITIONS PARAMETER Digital supply range Analogue supply range Ground AGND, DGND Difference DGND to AGND Analogue supply current Digital supply current Analogue supply current Digital supply current Note: DVDD must be equal to, or less than the AVDD supply (i.e. DVDD = AVDD = +5V; DVDD = AVDD = +3.3V; DVDD = +3.3V AVDD = +5V) ...
Page 7
... WM8740 Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, T PARAMETER SYMBOL Analogue Output Levels Output level differential Minimum resistance load Maximum capacitance load Output DC level Reference Levels Potential divider resistance Voltage at VMIDL/VMIDR Notes: 1. Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured ‘A’ ...
Page 8
... WM8740 SCKI Figure 2 System Clock Timing Requirements Test Conditions AVDD, DVDD = 5V, AGND, DGND = 0V, T PARAMETER System Clock Timing Information System clock pulse width high System clock pulse width low System clock cycle time ML/I2S MC/DM1 MD/DM0 Figure 3 Program Register Input Timing – SPI Compatible Serial Control Mode ...
Page 9
... INTERNAL POWER ON RESET CIRCUIT Figure 4 Internal Power On Reset Circuit Schematic The WM8740 includes an internal Power On Reset Circuit which is used reset the digital logic into a default state after power up. Figure 4 shows a schematic of the internal POR circuit. The POR circuit is powered from AVDD. The ...
Page 10
... WM8740 Figure 6 Typical Power Up Sequence Where AVDD is Powered Before DVDD Figure 7 Typical Power Up Sequence Where AVDD is Powered and VMIDLL has Charged Before DVDD Typical POR Operation (typical values, not tested) SYMBOL V pora V pord V porr V pora_off V pord_off w TYP UNIT 0.35 V 0.8 V 0.85 V 2.6 V 0.8 V Production Data PD, Rev 4 ...
Page 11
... WM8740 In a real application the designer is unlikely to have control of the relative power up sequence of AVDD and DVDD. Using the POR circuit to monitor VMIDLL ensures a reasonable delay between applying power to the device and Device Ready. Figure 5 and Figure 6 show typical power up scenarios in a real system. Both AVDD and DVDD must be established and VMIDL must have reached the threshold V be written to ...
Page 12
... This mode allows the use of alternative digital filters, such as the Pacific Microsonics PMD100 HDCD filter. In addition to the normal stereo operating mode the WM8740 may also be used in dual differential mode with either the left or right channel (selectable) being output dual differentially. Two WM8740s can then be used in parallel to implement a stereo channel, each supporting a single channel differentially. Note that this mode uses 2 pairs of differential outputs for each channel – ...
Page 13
... WM8740 NORMAL SAMPLE RATE In normal mode, the data is input serially on one pin for both left and right channels. Data can be “right justified” meaning that the last 16 bits (depending on chosen PCM word length) that were clocked in prior to the transition on LRCIN are valid. ...
Page 14
... WM8740 INPUT SAMPLE RATE Due to the higher speed of the interface mode, audio data is input on two pins. The MODE pin (pin 24) is used as the second input for the right channel data and left data is input on DIN (pin2). In this mode, software control of the device is not available. The data can be input in two formats, left or right justified, selectable by ML/I2S and two word lengths ( bit), selectable by CSBIWO ...
Page 15
... SOFTWARE CONTROL INTERFACE The WM8740 can be controlled using a 3-wire serial interface. MD/DM0 (pin 26) is used for the program data, MC/DM1 (pin 22) is used to clock in the program data and ML/I2S (pin 28) is use to latch in the program data. The 3-wire interface protocol is shown in Figure 6. CSB/IWO (pin 23) must be low when writing ...
Page 16
... WM8740 REGISTER MAP WM8740 controls the special functions using 4 program registers, which are 16-bits long. These registers are all loaded through input pin MD/DM0. After the 16 data bits are clocked in, ML/I2S is used to latch in the data to the appropriate register. Table 5 shows the complete mapping of the 4 registers ...
Page 17
... WM8740 Table 7 Attenuation Control Level Bit 2 in Reg3 is used to control the attenuator (ATC). When ATC is “high”, the attenuation data loaded in program register 0 is used for both the left and the right channels. When ATC is low, the attenuation data for each register is applied separately to left and right channels. ...
Page 18
... WM8740 POLARITY OF LR INPUT CLOCK The left channel data for a particular sample instant is always input first, then the right channel data. LRP (REG3, B1) Table 12 Polarity of LR Input Clock INDIVIDUAL OR COMMON ATTENUTATION CONTROL ATC (REG3, B2) Table 13 Individual or Common Attenuation Control DIGITAL FILTER ROLL-OFF SELECTION ...
Page 19
... Table 18. DIFF[1:0] B[5:4]) Table 18 Differential Output Modes Using these controls a pair of WM8740 devices may be used to build a dual differential stereo implementation with higher performance and differential output. Note: DIFFHW mode pin may be used to achieve the same result by hardware means. CLOCK LOSS DETECTOR DISABLE ...
Page 20
... WM8740 MUTE MODES The device has various mute modes. Reg bit OPE = ‘1’ MUTEB pin AUTOMUTE (detect 1024 zero input samples) Reg bit MUT Gain = 00 (left and right) RAM initialise Loss of system clock No LRCLK or invalid SCLK/LRCLK ratio RB Power-on reset Table 20 Mute Modes • ...
Page 21
... WM8740 FILTER RESPONSES Figure 12 Digital Filter Response (Sharp Roll-off Mode) Figure 14 Digital Filter Response (Slow Roll-off Mode) 0 -20 -40 -60 -80 -100 -120 0 0.2 0.4 0.6 0.8 1 Frequency (Fs) Figure 16 Digital Filter Response 128fs Mode (192kHz Sample Rate) Normal Mode – Solid, Slow Mode – Dashed w Figure 13 Digital Filter Response (Sharp Roll-off Mode) Figure 15 Digital Filter Response (Slow Roll-off Mode) 1 ...
Page 22
... WM8740 1 0.8 0.6 0.4 0.2 0 -0.2 -0 Time (input samples) Figure 17 Impulse Response (Normal Roll-off, no De-emphasis) 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -6.0 -7.0 -8.0 -9.0 -10.0 0 2000 4000 6000 8000 Frequency (Fs) Figure 19 De-emphasis frequency response (fs=32kHz) 0.0 -1.0 -2.0 -3.0 -4.0 -5.0 -6.0 -7.0 -8.0 -9.0 -10.0 0 2000 4000 6000 8000 10000 Frequency (Fs) Figure 21 De-emphasis frequency response (fs=48kHz 0.8 0.6 0.4 0.2 0 -0.2 -0 Figure 18 Impulse Response (Slow Roll-off, ...
Page 23
... WM8740 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 0 2000 4000 6000 8000 10000 Frequency (Fs) Figure 23 De-emphasis frequency response error (fs=44.1kHz) w 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 0 12000 14000 16000 18000 20000 Figure 24 De-emphasis frequency response error (fs=48kHz) Production Data 2000 4000 6000 8000 10000 12000 14000 16000 Frequency (Fs) PD, Rev 4.3, August 2009 18000 ...
Page 24
... WM8740 APPLICATIONS INFORMATION RECOMMENDED EXTERNAL COMPONENTS DVDD + C 1 DGND Software I/F or Hardware Control Audio Serial Data I/F System Clock Input Notes: 1. AGND and DGND should be connected as close to the WM8740 as possible and C should be positioned as close to the WM8740 as possible Capacitor type used can have a big effect on device performance recommended that capacitors with very low ESR are used and that ceramics are either NPO or COG type material to achieve best performance from the WM8740 ...
Page 25
... WM8740 SUGGESTED DIFFERENTIAL OUTPUT FILTER CIRCUIT Figure 26 Suggested Differential Output Filter Circuit RECOMMENDED DUAL DIFFERENTIAL HARDWARE SETUP Figure 27 Recommended Dual Differential Hardware Setup w Production Data PD, Rev 4.3, August 2009 25 ...
Page 26
... WM8740 PACKAGE DIMENSIONS DS: 28 PIN SSOP (10.2 x 5.3 x 1.75 mm Dimensions Symbols (mm) MIN NOM A ----- A 0. 1.65 1. 0.22 c 0.09 D 9.90 10.20 e 0.65 BSC E 7.40 7.80 E 5.00 5. 0.55 0.75 L 1.25 REF 1 o θ 0 JEDEC.95, MO-150 REF: 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. ...
Page 27
... WM8740 IMPORTANT NOTICE Wolfson Microelectronics plc (“Wolfson”) products and services are sold subject to Wolfson’s terms and conditions of sale, delivery and payment supplied at the time of order acknowledgement. Wolfson warrants performance of its products to the specifications in effect at the date of shipment. Wolfson reserves the right to make changes to its products and specifications or to discontinue any product or service without notice ...