WM8727GED/RV

WM8727 WOLFSON | Alldatasheet

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WOLFSON MICROELECTRONICS plc www.wolfsonmicro.com Production Data, April 2004, Rev 4.1 Copyright 2004 Wolfson Microelectronics plc

DESCRIPTION

The WM8727 is a high performance stereo DAC designed for audio applications such as DVD, home theatre systems, and digital TV. The WM8727 supports data input word lengths from 16 to 24-bits and sampling rates up to 192kHz. The WM8727 consists of a serial interface port, digital interpolation filters, multi-bit sigma delta modulators and stereo DAC in a very small 8-pin SOIC package. The WM8727 supports a 16-24-bit I 2S digital audio interface. The WM8727 is an ideal device to interface to AC-3 , DTS, and MPEG audio decoders for surround sound applications, or for use in DVD players, including supporting the implementation of 2 channels at 192kHz for high-end DVD-Audio applications.

FEATURES

• Stereo DAC
• Audio Performance - 98dB SNR (‘A’ weighted @ 48kHz) DAC - -84dB THD
• DAC Sampling Frequency: 8kHz – 192kHz
• Audio Data Interface Format - 16-24-Bit I 2S
• 2.7V – 5.5V Supply Operation
• 8-pin SOIC Package
• Exceeds Dolby Class A Performance Requirements

APPLICATIONS

• D V D P l a y e r s
• D i g i t a l T V
• Digital Set Top Box BLOCK DIAGRAM SERIAL INTERFACE MUTE BCKIN VOUTL VOUTR SIGMA DELTA MODULATOR LRCIN DIN MUTE SIGMA DELTA MODULATOR DIGITAL FILTERS MCLK LOW PASS FILTER LOW PASS FILTER RIGHT DACLEFT DAC GNDVDD W WM8727

w PD Rev 4.1 April 2004 TABLE OF CONTENTS

w PD Rev 4.1 April 2004 PIN CONFIGURATION WM8727 VDD VOUTR VOUTL GND MCLK LRCIN DIN BCKIN

ORDERING INFORMATION

WM8727ED -25 to +85 oC 8-pin SOIC MSL1 240 oC WM8727ED/R -25 to +85 oC 8-pin SOIC (tape and reel) MSL1 240 oC WM8727GED/V -25 to +85 oC 8-pin SOIC (lead free) MSL2 260 oC WM8727GED/RV -25 to +85 oC 8-pin SOIC (lead free, tape and reel) MSL2 260 oC Note: Reel Quantity = 3,000 PIN DESCRIPTION PIN NAME TYPE DESCRIPTION

1 DIN Digital input Serial audio data input

2 BCKIN Digital input Bit clock input

3 LRCIN Digital input Sample rate clock input

4 MCLK Digital input System clock input

5 VOUTR Analogue output Right channel DAC output

6 GND Supply Analogue ground supply

7 VDD Supply Positive supply

8 VOUTL Analogue output Left channel DAC output

Note: Digital input pins have Schmitt trigger input buffers.

w PD Rev 4.1 April 2004 ABSOLUTE MAXIMUM RATINGS Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical Characteristics at the test conditions specified. ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage of this device. Wolfson tests its package types according to IPC/JEDEC J-STD-020B for Moisture Sensitivity to determine acceptable storage conditions prior to surface mount assembly. These levels are: MSL1 = unlimited floor life at <30°C / 85% Relative Humidity. Not normally stored in moisture barrier bag. MSL2 = out of bag storage for 1 year at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag. MSL3 = out of bag storage for 168 hours at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag. CONDITION MIN MAX Supply voltage -0.3V +7V Voltage range digital inputs GND -0.3V VDD +0.3V Master Clock Frequency 50MHz Operating temperature range, TA -25°C +85 °C Storage temperature prior to soldering 30°C max / 85% RH max Storage temperature after soldering -65°C +150 °C DC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Supply range VDD 2.7 5.5 V Ground GND 0 V Supply current VDD = 5V 27 mA Supply current VDD = 3.3V 23 mA Power down current (note 3) VDD = 3.3V 0.5 mA

w PD Rev 4.1 April 2004

ELECTRICAL CHARACTERISTICS

VDD = 5V, GND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Digital Logic Levels (TTL Levels) Input LOW level V IL 0 . 8 V Input HIGH level V IH 2 V Output LOW V OL IOL = 2mA 0.10 x VDD V Output HIGH V OH IOH = 2mA 0.9 x VDD V DAC Output (Load = 10kΩΩΩΩ 50pF) 0dBFs Full scale output voltage At DAC outputs 1.2 x VDD/5 V RMS SNR (Note 1,2) A-weighted, @ fs = 48kHz 98 dB SNR (Note 1,2) A-weighted @ fs = 96kHz 95 dB SNR (Note 1,2) A-weighted @ fs = 192kHz 92 dB SNR (Note 1,2) A-weighted, @ fs = 48kHz VDD = 3.3V 95 dB SNR (Note 1,2) A-weighted @ fs = 96kHz VDD = 3.3V 95 dB SNR (Note 1,2) Non ‘A’ weighted @ fs = 48kHz 92 dB THD 1kHz, 0dBFs -84 dB Dynamic range (Note 2) 1kHz, THD+N @ -60dBFs 98 dB Analogue Output Levels Load = 10kΩ, 0dBFS 1.2 V RMS Output level Load = 10kΩ, 0dBFS, (VDD = 3.3V)

0.79 V RMS

± 1 % F S R To midrail or a.c. coupled 1 k Ω Minimum resistance load To midrail or a.c. coupled (VDD = 3.3V) 1 k Ω Maximum capacitance load 5V or 3.3V 100 pF Output d.c. level V D D / 2 V Power On Reset (POR) POR threshold 1 . 8 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’ we ighted over a 20Hz to 20kHz bandwidth. 2. All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use such a filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic specification values. 3. Power down occurs 1.5 µs after MCLK stops.

w PD Rev 4.1 April 2004 Test Conditions VDD = 5V, GND = 0V, TA = +25oC, fs = 48kHz, MCLK = 256fs unless otherwise stated. PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Audio Data Input Timing Information BCKIN cycle time tBCY 40 ns BCKIN pulse width high t BCH 16 ns BCKIN pulse width low tBCL 16 ns LRCIN set-up time to BCKIN rising edge tLRSU 8 n s LRCIN hold time from BCKIN rising edge tLRH 8 n s DIN set-up time to BCKIN rising edge tDS 8 n s DIN hold time from BCKIN rising edge tDH 8 n s

w PD Rev 4.1 April 2004 DEVICE DESCRIPTION GENERAL INTRODUCTION The WM8727 is a high performance DAC designed for digital consumer audio applications. The range of features make it ideally suited for use in DVD players, AV receivers and other consumer audio equipment. The WM8727 is a complete 2-channel stereo audio digital-to-analogue converter, including digital interpolation filter, multi-bit sigma delta with dither, and switched capacitor multi-bit stereo DAC and output smoothing filters. It is fully compatible and an ideal partner for a range of industry standard microprocessors, controllers and DSPs. A novel multi bit sigma-delta DAC design is used, utilising a 128x oversampling rate, to optimise signal to noise performance and offer increased clock jitter tolerance. (In ‘high-rate’ operation, the oversampling ratio is 64x for system clocks of 128fs or 192fs) Operation using master clocks of 256fs, 384fs, 512fs or 768fs is provided, selection between clock rates being automatically controlled. Sample rates (fs) from less than 8ks/s to 96ks/s are allowed, provided the appropriate system clock is input. Support is also provided for up to 192ks/s using a master clock of 128fs or 192fs. The audio data interface supports 16-24-bit I 2S (Philips left justified, one bit delayed) interface format. A DSP interface is also supported, enhancing the interface options for the user. A single 2.7-5.5V supply may be used, the output amplitude scaling with absolute supply level. Low supply voltage operation and low current consumption combined with the low pin count small package make the WM8727 attractive for many consumer applications. The device is packaged in a small 8-pin SOIC. DAC CIRCUIT DESCRIPTION The WM8727 DAC is designed to allow playback of 24-bit PCM audio or similar data with high resolution and low noise and distortion. Sample rates up to 192ks/s may be used, with much lower sample rates acceptable provided that the ratio of sample rate (LRCIN) to system clock (MCLK) is maintained at one of the required rates. The two DACs on the WM8727 are implemented using sigma-delta oversampled conversion techniques. These require that the PCM samples are digitally filtered and interpolated to generate a set of samples at a much higher rate than the up to 192ks/s input rate. This sample stream is then digitally modulated to generate a digital pulse stream that is then converted to analogue signals in a switched capacitor DAC. The advantage of this technique is that the DAC is linearised using noise shaping techniques, allowing the 24-bit resolution to be met using non- critical analogue components. A further advantage is that the high sample rate at the DAC output means that smoothing filters on the output of the DAC need only have fairly crude characteristics in order to remove the characteristic steps, or images, on the output of the DAC. To ensure that generation of tones characteristic to sigma-delta convertors is not a problem, dithering is used in the digital modulator and a higher order modulator is used. The multi-bit switched capacitor technique used in the DAC reduces sensitivity to clock jitter, and dramatically reduces out of band noise compared to switched current or single bit techniques used in other implementations. The outputs of the 2 DACs are buffered out of the device by buffer amplifiers. These amplifiers will source load currents of several mA and sink current up to 1.5mA allowing significant loads to be driven. The output source is active and the sink is Class A, i.e. fixed value, so greater loads might be driven if an external ‘pull-down’ resistor is connected at the output. Typically an external low pass filter circuit will be used to remove residual out of band noise characteristic of delta sigma converters. However, the advanced multi-bit DAC used in WM8727 produces far less out of band noise than single bit traditional sigma delta DACs, and so in many applications this filter may be removed, or replaced with a simple RC pole.

w PD Rev 4.1 April 2004 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. The external master clock can be applied directly through the MCLK input pin with no configuration necessary for sample rate selection. Note that on the WM8727, MCLK is used to derive clocks for the DAC path. The DAC path consists of DAC sampling clock, DAC digital filter clock and DAC digital audio interface timing. In a system where there are a number of possible sources for the reference clock it is recommended that the clock source with the lowest jitter be used to optimise the performance of the DAC. The device can be powered down by stopping MCLK. In this state the power consumption is substantially reduced. DIGITAL AUDIO INTERFACE Audio data is applied to the internal DAC filters via the Digital Audio Interface. The WM8727 supports the popular I 2S audio interface format. The WM8727 supports word lengths of 16-24 bits (MSB first). The word length may be any value up to 24-bits. (If a word length shorter than 24-bits is used, the unused bits will be padded with zeros). ‘Packed’ mode (i.e. only 32 or 48 clocks per LRCIN period) operation is also supported. If a ‘packed’ format of 16-bit word length is applied (16 BCKINS per LRCIN half period), the device auto-detects this mode and switches to 16-bit data length. The digital audio interface receives data on the DIN input. Audio Data is time multiplexed with LRCIN indicating whether the left or right channel is present. LRCIN is also used as a timing reference to indicate the beginning or end of the data words. The minimum number of BCKINs per LRCIN period is 2 times the selected word length. LRCIN must be high for a minimum of word length BCKINs and low for a minimum of word length BCKINs. Any mark to space ratio on LRCIN is acceptable provided the above requirements are met. In the I 2S mode, the MSB is sampled on the second rising edge of BCKIN following a LRCIN transition. LRCIN is low during the left samples and high during the right samples. LEFT CHANNEL RIGHT CHANNEL LRCIN BCKIN DIN 1/fs n321 n-2 n-1 LSBMSB n321 n-2 n-1 LSBMSB

1 BCKIN1 BCKIN

Figure 3 I2S Mode Timing Diagram

w PD Rev 4.1 April 2004 AUDIO DATA SAMPLING RATES The master clock for WM8727 supports audio sampling rates from 128fs to 768fs, where fs is the audio sampling frequency (LRCIN) typically 32kHz, 44.1kHz, 48kHz, 96kHz or 192kHz. The master clock is used to operate the digital filters and the noise shaping circuits. The WM8727 has a master clock detection circuit that automatically determines the relation between the master clock frequency and the sampling rate (to within +/- 8 master clocks). If there is a greater than 8 clocks error, the interface shuts down the DAC and mutes the output. The master clock should be synchronised with LRCIN, although the WM8727 is tolerant of phase differences or jitter on this clock. MASTER CLOCK FREQUENCY (MHZ) (MCLK) SAMPLING RATE (LRCIN) 128fs 192fs 256fs 384fs 512fs 768fs 96kHz 12.288 18.432 24.576 36.864 Unavailable Unavailable 192kHz 24.576 36.864 Unavailable Unavailable Unavailable Unavailable Table 1 Master Clock Frequencies Versus Sampling Rate

w PD Rev 4.1 April 2004 APPLICATIONS INFORMATION RECOMMENDED EXTERNAL COMPONENTS VDD GND WM8727 Notes: 1. C2 should be positioned as close to the WM8727 as possible. 2. Capacitor types should be carefully chosen. Capacitors with very low ESR are recommended for optimum performance. 3. C3 and C4 not required if using the recommended low pass filter in Figure 9. C VDD VOUTR VOUTL AC-Coupled VOUTR/L to External LPF

4 MCLK

2 BCKIN

1 DIN

3 LRCIN

Figure 10 External Component Diagram RECOMMENDED EXTERNAL COMPONENTS VALUES COMPONENT REFERENCE SUGGESTED VALUE C1 10 µF De-coupling for VDD C2 0.1 µF De-coupling for VDD C3 and C4 10 µF Output AC coupling caps to remove midrail DC level from outputs Table 3 External Components Description

w PD Rev 4.1 April 2004 RECOMMENDED ANALOGUE LOW PASS FILTER (OPTIONAL) +VS -VS 10uF 51Ω 7.5KΩ 680pF 1.8kΩ 47kΩ 4.7kΩ 4.7kΩ 1.0nF Figure 11 Recommended Low Pass Filter (Optional) An external low pass filter is recommended (see Figure 20) if the device is driving a wideband amplifier. In some applications, a passive RC filter may be adequate. PCB LAYOUT RECOMMENDATIONS Care should be taken in the layout of the PCB that the WM8727 is to be mounted to. The following notes will help in this respect: 1. The VDD supply to the device should be as noise free as possible. This can be accomplished to a large degree with a 10uF bulk capacitor placed locally to the device and a 0.1uF high frequency decoupling capacitor placed as close to the VDD pin as possible. It is best to place the 0.1uF capacitor directly between the VDD and GND pins of the device on the same layer to minimize track inductance and thus improve device decoupling effectiveness. 2. Separate analogue and digital track routing from each other . The device is split into analogue (pins 5 – 8) and digital (pins 1 – 4) sections that allow the routing of these signals to be easily separated. By physically separating analogue and digital signals, crosstalk from the PCB can be minimized. 3. Use an unbroken solid GND plane . To achieve best performance from the device, it is advisable to have either a GND plane layer on a multilayer PCB or to dedicate one side of a 2 layer PCB to be a GND plane. For double sided implementations it is best to route as many signals as possible on the device mounted side of the board, with the opposite side acting as a GND plane. The use of a GND plane greatly reduces any electrical emissions from the PCB and minimizes crosstalk between signals. An evaluation board is available for the WM8727 that demonstrates the above techniques and the excellent performance achievable from the device. This can be ordered or the User manual downloaded from the Wolfson web site at www.wolfsonmicro.com

w PD Rev 4.1 April 2004 PACKAGE DRAWING DM009.B D: 8 PIN SOIC 3.9mm Wide Body Symbols Dimensions (mm) Dimensions (Inches) M I NM A XM I NM A X A 1.35 1.75 0.0532 0.0688 A1 0.10 0.25 0.0040 0.0098 B 0.33 0.51 0.0130 0.0200 C 0.19 0.25 0.0075 0.0098 D 4.80 5.00 0.1890 0.1968 e 1.27 BSC 0.050 BSC E 3.80 4.00 0.1497 0.1574 h 0.25 0.50 0.0099 0.0196 H 5.80 6.20 0.2284 0.2440 L 0.40 1.27 0.0160 0.0500 αααα 0o 8o 0o 8o REF: JEDEC.95, MS-012 NOTES: A. ALL LINEAR DIMENSIONS ARE IN MILLIMETERS (INCHES). B. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. C. BODY DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSION, NOT TO EXCEED 0.25MM (0.010IN). D. MEETS JEDEC.95 MS-012, VARIATION = AA. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS. C h x 45o α L A A1 SEATING PLANE -C- 0.10 (0.004) D E H Be

w PD Rev 4.1 April 2004 IMPORTANT NOTICE Wolfson Microelectronics plc (WM) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, tha t information being relied on is current. All products are sold subject to the WM terms and conditions of sale supplied at the ti me of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. WM warrants performance of its products to the specifications applicable at the time of sale in accordance with WM’s standard warranty. Testing and other quality control techniques are utilised to the extent WM deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. In order to minimise risks associated with customer applications, adequate design and operating safeguards must be used by the customer to minimise inherent or procedural hazards. Wolfson products are not authorised for use as critical components in life support devices or systems without the express written approval of an officer of the company. Life support devices or systems are devices or systems that are intended for surgical implant into the body, or support or sustain life, and whose fail ure to perform when properly used in accordance with instructions for use provided, can be reasonably expected to result in a significant injury to the user. A critical component is any component of a life support device or system whose failure to perfo rm can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. WM assumes no liability for applications assistance or customer product design. WM does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual proper ty right of WM covering or relating to any combination, machine, or process in which such products or services might be or are used. WM’s publication of information regarding any third party’s products or services does not constitute WM’s approval, license, warranty or endorsement thereof. Reproduction of information from the WM web site or datasheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations and notices. Representation or reproduction of this information with alteration voids all warranties provided for an associated WM product or service, is an unfair and deceptive business practice, and WM is not responsible nor liable for any such use. Resale of WM’s products or services with statements different from or beyond the parameters stated by WM for that product or service voids all express and any implied warranties for the associated WM product or service, is an unfair and deceptive business practice, and WM is not responsible nor liable for any such use. ADDRESS: Wolfson Microelectronics plc Westfield House

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