WM8940

w Mono CODEC with Speaker Driver DESCRIPTION The WM8940 is a low power, high quality mono CODEC designed for portable applications such as digital still cameras or camcorders. The device integrates support for a differential or single ended mic, and includes drivers for speakers or headphone, and mono line output. External component requirements are reduced as no separate microphone or headphone amplifiers are required. Advanced Sigma Delta Converters are used along with digital decimation and interpolation filters to give high quality audio at sample rates from 8 to 48ks/s. A selectable high pass filter and four fully-programmable notch filters are available in the ADC path. An advanced mixed signal ALC function with noise gate is provided, while readback of PGA gain during ALC operation is supported. The digital audio interface supports Alaw and µ-law companding. An on-chip PLL is provided to generate the required Master Clock from an external reference clock. The PLL clock can also be output if required elsewhere in the system. The WM8940 operates at supply voltages from 2.5 to 3.6V, although the digital supplies can operate at voltages down to 1.71V to save power. Different sections of the chip can also be powered down under software control using the selectable two or three wire control interface. WM8940 is supplied in a very small 4x4mm QFN package, offering high levels of functionality in minimum board area, with high thermal performance. WM8940 FEATURES • • • • • • • • • Mono CODEC: Audio sample rates:8, 11.025, 16, 22.05, 24, 32, 44.1, 48kHz DAC SNR 98dB, THD -84dB (‘A’-weighted @ 8 – 48ks/s) ADC SNR 94dB, THD -80dB (‘A’-weighted @ 8 – 48ks/s) On-chip Headphone/Speaker Driver - 40mW output power into 16Ω - BTL speaker drive 0.4W into 8Ω Additional MONO Line output Multiple analog or ‘Aux’ inputs, plus analog bypass path Mic Preamps: Differential or single end Microphone Interface - Programmable preamp gain - Pseudo differential inputs with common mode rejection - Programmable ALC / Noise Gate in ADC path Low-noise bias supplied for electret microphones • OTHER FEATURES • Digital Playback Limiter • Programmable high pass filter (wind noise reduction) • 4 notch filters (narrowband noise suppression) • On-chip PLL • Low power, low voltage - 2.5V to 3.6V (digital: 1.71V to 3.6V) • 4x4x0.9mm 24 lead QFN package APPLICATIONS • • Digital still cameras and camcorders General purpose mono audio CODEC WOLFSON MICROELECTRONICS plc To receive regular email updates, sign up at http://www.wolfsonmicro.com/enews/ Pre-Production, Rev 3.0, February 2007, Copyright ©2007 Wolfson Microelectronics plc WM8940 BLOCK DIAGRAM Pre-Production w Pre-Production, Rev 3.0, February 2007 2 Pre-Production WM8940 TABLE OF CONTENTS DESCRIPTION .......................................................................................................1 FEATURES.............................................................................................................1 APPLICATIONS .....................................................................................................1 BLOCK DIAGRAM .................................................................................................2 TABLE OF CONTENTS .........................................................................................3 PIN CONFIGURATION...........................................................................................5 ORDERING INFORMATION ..................................................................................5 PIN DESCRIPTION ................................................................................................6 ABSOLUTE MAXIMUM RATINGS.........................................................................7 RECOMMENDED OPERATING CONDITIONS .....................................................7 ELECTRICAL CHARACTERISTICS ......................................................................8 TERMINOLOGY .......................................................................................................... 10 POWER CONSUMPTION ....................................................................................11 SIGNAL TIMING REQUIREMENTS .....................................................................12 SYSTEM CLOCK TIMING ........................................................................................... 12 AUDIO INTERFACE TIMING – MASTER MODE ........................................................ 12 AUDIO INTERFACE TIMING – SLAVE MODE............................................................ 13 CONTROL INTERFACE TIMING – 3-WIRE MODE .................................................... 14 CONTROL INTERFACE TIMING – 2-WIRE MODE .................................................... 15 DEVICE DESCRIPTION.......................................................................................16 INTRODUCTION ......................................................................................................... 16 INPUT SIGNAL PATH ................................................................................................. 17 ANALOGUE TO DIGITAL CONVERTER (ADC).......................................................... 22 INPUT LIMITER / AUTOMATIC LEVEL CONTROL (ALC) .......................................... 27 OUTPUT SIGNAL PATH ............................................................................................. 40 ANALOGUE OUTPUTS............................................................................................... 44 OUTPUT SWITCH ...................................................................................................... 47 DIGITAL AUDIO INTERFACES................................................................................... 50 AUDIO SAMPLE RATES ............................................................................................. 54 MASTER CLOCK AND PHASE LOCKED LOOP (PLL) ............................................... 54 COMPANDING............................................................................................................ 57 GENERAL PURPOSE INPUT/OUTPUT...................................................................... 59 CONTROL INTERFACE.............................................................................................. 59 3-WIRE SERIAL CONTROL MODE ............................................................................ 61 READBACK IN 3-WIRE MODE ................................................................................... 61 2-WIRE SERIAL CONTROL MODE ............................................................................ 62 RESETTING THE CHIP .............................................................................................. 62 POWER SUPPLIES .................................................................................................... 62 POWER MANAGEMENT ............................................................................................ 64 POP MINIMISATION ................................................................................................... 65 REGISTER MAP...................................................................................................66 REGISTER BITS BY ADDRESS ................................................................................. 67 DIGITAL FILTER CHARACTERISTICS ...............................................................78 TERMINOLOGY .......................................................................................................... 78 DAC FILTER RESPONSES......................................................................................... 79 ADC FILTER RESPONSES......................................................................................... 79 HIGHPASS FILTER..................................................................................................... 80 NOTCH FILTERS AND LOW PASS FILTER............................................................... 81 w Pre-Production, Rev 3.0, February 2007 3 WM8940 Pre-Production NOTCH FILTER WORKED EXAMPLE........................................................................ 82 APPLICATIONS INFORMATION .........................................................................83 RECOMMENDED EXTERNAL COMPONENTS .......................................................... 83 PACKAGE DIAGRAM ..........................................................................................84 IMPORTANT NOTICE ..........................................................................................85 ADDRESS ................................................................................................................... 85 w Pre-Production, Rev 3.0, February 2007 4 Pre-Production WM8940 PIN CONFIGURATION TOP VIEW ORDERING INFORMATION ORDER CODE W M8940GEFL/V W M8940GEFL/RV Note: Reel Quantity = 3,500 TEMPERATURE RANGE -25°C to +85°C -25°C to +85°C PACKAGE 24-lead QFN (4x4x0.9mm) (Pb-free) 24-lead QFN (4x4x0.9mm) (Pb-free, tape and reel) MOISTURE SENSITIVITY LEVEL MSL3 MSL3 PACKAGE BODY TEMPERATURE 260oC 260oC w Pre-Production, Rev 3.0, February 2007 5 WM8940 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 NAME MICBIAS AVDD AGND DCVDD DBVDD DGND ADCDAT DACDAT FRAME BCLK MCLK CSB/GPIO SCLK SDIN MODE / GPIO MONOOUT SPKOUTP SPKGND SPKOUTN SPKVDD AUX VMID MICN MICP Supply Supply Supply Supply Supply Digital Output Digital Input Digital Input / Output Digital Input / Output Digital Input Digital Input / Output Digital Input Digital Input / Output Digital Input Analogue Output Analogue Output Supply Analogue Output Supply Analogue Input Reference Analogue Input Analogue Input TYPE Analogue Output Microphone bias Analogue supply Analogue ground Digital Supply (Core) Digital supply (Input/Output) Digital ground ADC digital audio data output DAC digital audio data input DAC and ADC sample rate clock or frame synch Digital audio port clock Master clock input 3-Wire control interface chip select or GPIO pin. DESCRIPTION Pre-Production 3-Wire control interface clock Input / 2-Wire control interface clock input 3-Wire control interface data Input / 2-Wire control interface data input Control interface mode selection pin or GPIO pin. Mono output Speaker output positive Speaker ground Speaker output negative Speaker supply Auxiliary analogue input Decoupling for midrail reference voltage Microphone negative input (common mode) Microphone positive input Note: 1. 2. It is recommended that the QFN ground paddle should be connected to analogue ground on the application PCB. Refer to the application note WAN_0118 on “Guidelines on How to Use QFN Packages and Create Associated PCB Footprints” w Pre-Production, Rev 3.0, February 2007 6 Pre-Production WM8940 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 0.546fs 0.546fs -55 29/fs dB +/- 0.035dB -6dB 0 0.5fs +/-0.035 dB 0.454fs 3.7 10.4 21.6 Hz f > 0.546fs 0.546fs -60 21/fs dB +/- 0.025dB -6dB 0 0.5fs +/- 0.025 dB 0.454fs TEST CONDITIONS MIN TYP MAX Pre-Production UNIT TERMINOLOGY 1. 2. 3. Stop Band Attenuation (dB) – the degree to which the frequency spectrum is attenuated (outside audio band) Pass-band Ripple – any variation of the frequency response in the pass-band region Note that this delay applies only to the filters and does not include additional delays through other digital circuits. See Table 62 for the total delay. PARAMETER Total Delay (ADC analogue input to digital audio interface output) Total Delay (Audio interface input to DAC analogue output) Table 62 Total Group Delay Notes 1. Wind noise filter is disabled. MIN 28/fs TYP 30/fs MAX 32/fs UNIT fs 33/fs 35/fs 37/fs fs w Pre-Production, Rev 3.0, February 2007 78 Pre-Production WM8940 DAC FILTER RESPONSES 0.2 0 -20 Response (dB) -40 -60 -80 -100 - 120 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 0.15 0.1 Response (dB) 0.05 0 -0.05 -0.1 -0.15 -0.2 0 0.1 0.2 Frequency (Fs) 0.3 0.4 0.5 Figure 38 DAC Digital Filter Frequency Response Figure 39 DAC Digital Filter Ripple ADC FILTER RESPONSES 0.2 0 -20 Response (dB) Response (dB) 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 -0.2 -40 -60 -80 -100 - 120 0 0.5 1 1.5 Frequency (Fs) 2 2.5 3 0 0.1 0.2 Frequency (Fs) 0.3 0.4 0.5 Figure 40 ADC Digital Filter Frequency Response Figure 41 ADC Digital Filter Ripple w Pre-Production, Rev 3.0, February 2007 79 WM8940 HIGHPASS FILTER Pre-Production The WM8940 has a selectable digital high pass filter in the ADC filter path. This filter has two modes, audio and applications. In audio mode the filter is a 1st order IIR with a cut-off of around 3.7Hz. In applications mode the filter is a 2nd order high pass filter with a selectable cut-off frequency. 5 0 -5 -10 Response (dB) 10 0 -10 Response (dB) 0 5 10 15 20 25 30 35 40 45 Frequency (Hz) -15 -20 -25 -30 -35 -40 -20 -30 -40 -50 - 60 0 200 400 600 Frequency (Hz) 800 1000 1200 Figure 42 ADC High pass Filter Response, HPFAPP=0 Figure 43 ADC High pass Filter Responses (48kHz), HPFAPP=1, all cut-off settings shown. 10 0 -10 Response (dB) 10 0 -10 -20 -30 -40 -50 -60 -20 Response (dB) -30 -40 -50 -60 -70 -80 0 200 400 600 Frequency (Hz) 800 1000 1200 -70 -80 -90 0 200 400 600 Frequency (Hz) 800 1000 1200 Figure 44 ADC High pass Filter Responses (24kHz), HPFAPP=1, all cut-off settings shown. Figure 45 ADC Highpass Filter Responses (12kHz), HPFAPP=1, all cutoff settings shown. w Pre-Production, Rev 3.0, February 2007 80 Pre-Production WM8940 The WM8940 supports four programmable notch filters. The fourth notch filter can be configured as a low pass filter. The following illustrates three digital notch filters, followed by a single low pass filter in the ADC filter path. Both the centre frequency and -3dB bandwidth are programmable for the notch filters. The cut off frequency is programmable for the low pass filter. The following graphs show the responses of 1) a single notch filter at three chosen centre frequencies, with three bandwidths for each, 2) the low pass filter at three chosen cut off frequencies and 3) the cascade of three notch filters followed by the low pass filter, each with a different centre / cut off frequency with three bandwidths for each. NOTCH FILTERS AND LOW PASS FILTER +0 -5 -10 -15 -20 -25 R E S P O N S E (dB) -30 -35 -40 -45 -50 -55 -60 20 50 100 200 500 1k Frequency (Hz) 2k 5k 10k 20k Figure 46 ADC Notch Filter Responses (48kHz); fc=100Hz, 1kHz, 10kHz; fb = 100Hz, 600Hz, 2kHz +0 -5 -10 R E S P O N S E -15 -20 -25 T (dB) -30 -35 -40 -45 -50 -55 -60 20 50 100 200 500 1k Frequency (Hz) 2k 5k 10k 20k Figure 47 ADC Low Pass Filter Responses (48kHz); fc= 1kHz, 5kHz, 10kHz w Pre-Production, Rev 3.0, February 2007 81 WM8940 Pre-Production +0 -5 R E S P O N S E (dB) -10 -15 -20 -25 -30 -35 -40 20 T 50 100 200 500 1k Frequency (Hz) 2k 5k 10k 20k Figure 48 Cumulative Notch + Low Pass Filters Responses (48kHz); NF0 fc = 1kHz; NF1 fc = 5kHz; NF2 fc = 10kHz; LPF fc = 11kHz; fb = 100Hz, 600Hz, 2kHz NOTCH FILTER WORKED EXAMPLE The following example illustrates how to calculate the a0 and a1 coefficients for a desired centre frequency and -3dB bandwidth. fc = 1000 Hz fb = 100 Hz fs = 48000 Hz w 0 = 2πfc / fs = 2π x (1000 / 48000) = 0.1308996939 rads w b = 2πfb / fs = 2π x (100 / 48000) = 0.01308996939 rads a0 = 1 − tan( w b / 2) 1 − tan(0.0130899693 9 / 2) = = 0.9869949627 1 + tan( w b / 2) 1 + tan( 0.0130899693 9 / 2) a1 = −(1 + a0 ) cos( w 0 ) = −(1 + 0.9869949627 ) cos(0.1308996939 ) = -1.969995945 NFn_A0 = -a0 x 213 = -8085 (rounded to nearest whole number) NFn_A1 = -a1 x 212 = 8069 (rounded to nearest whole number) These values are then converted to a 14-bit sign / magnitude notation: NFn_A0[13] = 1; NFn_A0[12:0] = 13’h1F95; NFn_A0 = 14’h3F95 = 14’b11111110010101 NFn_A1[13] = 0; NFn_A1[12:0] = 13’h1F85; NFn_A1 = 14’h1F85 = 14’b01111110000101 w Pre-Production, Rev 3.0, February 2007 82 Pre-Production WM8940 APPLICATIONS INFORMATION RECOMMENDED EXTERNAL COMPONENTS Figure 49 Recommended External Components w Pre-Production, Rev 3.0, February 2007 83 WM8940 PACKAGE DIAGRAM FL: 24 PIN QFN PLASTIC PACKAGE 4 X 4 X 0.9 mm BODY, 0.50 mm LEAD PITCH DETAIL 1 D2 19 24 D Pre-Production DM035.C 18 EXPOSED GROUND 6 PADDLE 1 4 E2 INDEX AREA (D/2 X E/2) E A SEE DETAIL 2 13 6 2X 12 e 7 b 1 bbb M C A B 2X aaa C aaa C TOP VIEW BOTTOM VIEW ccc C A3 A 0.08 C 5 DETAIL 1 DETAIL 2 45 degrees Datum L L1 1 C SEATING PLANE SIDE VIEW A1 DETAIL 2 0.32mm EXPOSED GROUND PADDLE e R Terminal tip e/2 W T A3 H b Exposed lead G Half etch tie bar DETAIL 2 Symbols A A1 A3 b D D2 E E2 e G H L L1 T W aaa bbb ccc REF: MIN 0.80 0 0.18 2.00 2.00 Dimensions (mm) NOM MAX NOTE 0.90 1.00 0.02 0.05 0.20 REF 1 0.25 0.30 4.00 2.15 4.00 2.15 0.50 BSC 0.213 0.1 0.40 0.1 0.2 2.25 2.25 2 2 0.30 0.03 0.50 0.15 7 Tolerances of Form and Position 0.15 0.10 0.10 JEDEC, MO-220, VARIATION VGGD-2. NOTES: 1. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.15 mm AND 0.30 mm FROM TERMINAL TIP. 2. FALLS WITHIN JEDEC, MO-220, VARIATION VGGD-2. 3. ALL DIMENSIONS ARE IN MILLIMETRES. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JEDEC 95-1 SPP-002. 5. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 6. REFER TO APPLICATIONS NOTE WAN_0118 FOR FURTHER INFORMATION REGARDING PCB FOOTPRINTS AND QFN PACKAGE SOLDERING. 7. DEPENDING ON THE METHOD OF LEAD TERMINATION AT THE EDGE OF THE PACKAGE, PULL BACK (L1) MAY BE PRESENT. 8. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. w Pre-Production, Rev 3.0, February 2007 84 Pre-Production WM8940 IMPORTANT NOTICE W olfson 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. Customers should therefore obtain the latest version of relevant information from Wolfson to verify that the information is current. Testing and other quality control techniques are utilised to the extent Wolfson deems necessary to support its warranty. Specific testing of all parameters of each device is not necessarily performed unless required by law or regulation. In order to minimise risks associated with customer applications, the customer must use adequate design and operating safeguards to minimise inherent or procedural hazards. Wolfson is not liable for applications assistance or customer product design. The customer is solely responsible for its selection and use of Wolfson products. Wolfson is not liable for such selection or use nor for use of any circuitry other than circuitry entirely embodied in a Wolfson product. Wolfson’s products are not intended for use in life support systems, appliances, nuclear systems or systems where malfunction can reasonably be expected to result in personal injury, death or severe property or environmental damage. Any use of products by the customer for such purposes is at the customer’s own risk. Wolfson does not grant any licence (express or implied) under any patent right, copyright, mask work right or other intellectual property right of Wolfson covering or relating to any combination, machine, or process in which its products or services might be or are used. Any provision or publication of any third party’s products or services does not constitute Wolfson’s approval, licence, warranty or endorsement thereof. Any third party trade marks contained in this document belong to the respective third party owner. Reproduction of information from Wolfson datasheets is permissible only if reproduction is without alteration and is accompanied by all associated copyright, proprietary and other notices (including this notice) and conditions. Wolfson is not liable for any unauthorised alteration of such information or for any reliance placed thereon. Any representations made, warranties given, and/or liabilities accepted by any person which differ from those contained in this datasheet or in Wolfson’s standard terms and conditions of sale, delivery and payment are made, given and/or accepted at that person’s own risk. Wolfson is not liable for any such representations, warranties or liabilities or for any reliance placed thereon by any person. ADDRESS W olfson Microelectronics plc Westfield House 26 Westfield Road Edinburgh EH11 2QB United Kingdom Tel :: +44 (0)131 272 7000 Fax :: +44 (0)131 272 7001 Email :: sales@wolfsonmicro.com w Pre-Production, Rev 3.0, February 2007 85