WM8959

w Mobile Multimedia DAC with Dual-Mode Class AB/D Speaker Driver DESCRIPTION The WM8959 is an ultra-low power hi-fi DAC designed for multimedia handsets. A powerful 1W speaker driver can operate in class D or AB modes, providing total flexibility to the system designer. Low leakage, high PSRR and pop/click suppression enable direct battery connection for the speaker supply. A flexible input configuration supports two microphone inputs (single-ended or differential), a stereo line input, and a mono differential line input. Four headphone drivers support fully differential headset drive, providing excellent crosstalk performance and bass response, maximising stereo effects, and allowing the removal of large and expensive headphone capacitors. The headphone outputs can also be configured to drive an ear speaker. A fully differential path to these outputs direct from the input pins is available to maximise signal quality and minimise power consumption. Stereo 24-bit sigma-delta DACs provide hi-fi quality audio playback, with a flexible digital audio interface supporting most commonly-used clocking schemes. An integrated low power PLL provides additional flexibility. The WM8959 is supplied in very small and thin 42-ball WCSP package, ideal for portable systems. WM8959 FEATURES • • • DAC SNR 99dB (‘A’ weighted), THD -84dB at 48kHz, 3.3V Stereo microphone interface 1W Speaker driver - 1W into 8Ω BTL speaker at 0.546 fs +/- 0.03dB -6dB 0.454 fs 0.546 fs -50 dB 0 0.5 fs +/- 0.03 dB 0.454 fs TEST CONDITIONS MIN TYP MAX Pre-Production UNIT DAC FILTERS MODE Normal Sloping Stopband GROUP DELAY 18 / fs 18 / fs w PP, May 2008, Rev 3.1 148 Pre-Production WM8959 DAC FILTER RESPONSES DAC STOPBAND ATTENUATION The DAC digital filter type is selected by the DAC_SB_FILT register bit as shown in Table 82. REGISTER ADDRESS R10 (0Ah) BIT 8 LABEL DAC_SB_FI LT DEFAULT 0b DESCRIPTION Selects DAC filter characteristics 0 = Normal mode 1 = Sloping stopband mode Table 82 DAC Filter Selection M AGNITUDE(dB) 10 -10 0 -30 -50 -70 0.5 1 1.5 2 2.5 3 M AGNITUDE(dB) 0.04 0.035 0.03 0.025 0.02 0.015 -90 -110 -130 -150 Frequency (fs) 0.01 0.005 0 -0.005 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Frequency (fs) Figure 87 DAC Digital Filter Frequency Response (Normal Mode) M AGNITUDE(dB) 10 -10 0 -30 -50 -70 -90 -110 -130 -150 Frequency (fs) 0.5 1 1.5 2 2.5 3 Figure 88 DAC Digital Filter Ripple (Normal Mode) M AGNITUDE(dB) 0.05 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3 -0.35 -0.4 -0.45 -0.5 Frequency (fs) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Figure 89 DAC Digital Filter Frequency Response (Sloping Stopband Mode) Figure 90 DAC Digital Filter Ripple (Sloping Stopband Mode) w PP, May 2008, Rev 3.1 149 WM8959 DE-EMPHASIS FILTER RESPONSES M AGNITUDE(dB) 0.3 M AGNITUDE(dB) Pre-Production 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 Frequency (Hz) 0 5000 10000 15000 20000 0.25 0.2 0.15 0.1 0.05 0 -0.05 -0.1 -0.15 Frequency (Hz) 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 Figure 91 De-Emphasis Digital Filter Response (32kHz) Figure 92 De-Emphasis Error (32kHz) M AGNITUDE(dB) 0.2 M AGNITUDE(dB) 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 Frequency (Hz) 0 5000 10000 15000 20000 25000 0.15 0.1 0.05 0 0 -0.05 -0.1 Frequency (Hz) 5000 10000 15000 20000 25000 Figure 93 De-Emphasis Digital Filter Response (44.1kHz) M AGNITUDE(dB) 0 0 -2 -4 -6 -8 -10 -12 Frequency (Hz) 5000 10000 15000 20000 25000 30000 Figure 94 De-Emphasis Error (44.1kHz) M AGNITUDE(dB) 0.15 0.1 0.05 0 0 -0.05 5000 10000 15000 20000 25000 30000 -0.1 -0.15 Frequency (Hz) Figure 95 De-Emphasis Digital Filter Response (48kHz) Figure 96 De-Emphasis Error (48kHz) w PP, May 2008, Rev 3.1 150 Pre-Production WM8959 APPLICATIONS INFORMATION SPEAKER SELECTION For filterless operation, it is important to select a speaker with appropriate internal inductance. The internal inductance and the speaker's load resistance create a low-pass filter with a cut-off frequency of: fc = RL / 2πL e.g. for an 8Ω speaker and required cut-off frequency of 20kHz, the speaker should be chosen to have an inductance of: L = RL / 2πfc = 8Ω / 2π * 20kHz = 64µH 8Ω speakers typically have an inductance in the range 20µH to 100µH. Care should be taken to ensure that the cut-off frequency of the speaker's internal filtering is low enough to prevent speaker damage. The class D outputs of the WM8959 operate at much higher frequencies than is recommended for most speakers, and the cut-off frequency of the filter should be low enough to protect the speaker. Figure 97 Speaker Equivalent Circuit PCB LAYOUT CONSIDERATIONS The efficiency of the speaker drivers is affected by the series resistance between the WM8959 and the speaker (e.g. inductor ESR) as shown in Figure 98. This resistance should be as low as possible to maximise efficiency. Figure 98 Speaker Connection Losses w PP, May 2008, Rev 3.1 151 WM8959 Pre-Production The distance between the WM8959 and the speakers should be kept to a minimum to reduce series resistance, and also to reduce EMI. Further reductions in EMI can be achieved by additional passive filtering and/or shielding as shown in Figure 99. When additional passive filtering is used, low ESR components should be chosen to minimise series resistance between the WM8959 and the speaker, maximising efficiency. LC passive filtering will usually be effective at reducing EMI at frequencies up to around 30MHz. To reduce emissions at higher frequencies, ferrite beads placed as close to the device as possible will be more effective. SPKP WM8959 SPKN SPKP EMI WM8959 SPKN Long, exposed tracks emit more EMI SPKP WM8959 SPKN SPKP WM8959 SPKN Short connection reduces EMI LOW ESR LOW ESR Shielding using PCB ground plane (or Vdd) reduces EMI SPKP WM8959 SPKN LC Filtering reduces EMI LC filtering is more effective at removing EMI at frequencies below ~30MHz Ferrite beads are more effective at removing EMI at frequencies above ~30MHz Ferrite beads reduce EMI Figure 99 EMI Reduction Techniques w PP, May 2008, Rev 3.1 152 Pre-Production WM8959 RECOMMENDED EXTERNAL COMPONENTS DVDD Vbatt AVDD 0.1 F 0.1 F 4.7 F 4.7 F 4.7 F WM8959 AVDD HPVDD SPKVDD DCVDD DBVDD MODE CSB/ADDR SCLK SDIN MCLK BCLK DACLRC DACDAT AGND HPGND SPKGND DGND MICBIAS CONTROL INTERFACE (2, 3 or 4-wire via GPIO) MICBIAS VMID 4.7 F 4.7 F AGND LOUT ROUT OUT3 220 F 220 F 16 or 32 OHM HEADPHONES 16 or 32 OHM EAR SPEAKER 8 OHM LOUDSPEAKER LINE OUTPUTS AUDIO INTERFACE MICBIAS 2k2 2k2 GPIO GPIO1 GPIO3/BCLK2 GPIO4/DACLRC2 GPIO5/DACDAT2 OUT4 SPKP SPKN HEADSET MIC HANDSET MIC 1F 1F 1F 1F LIN1 ROP LIN2 RON LIN3/GPI7 LOP LIN4/RXN LON RIN1 RIN2 RIN3/GPI8 RIN4/RXP 1F 1F 1F 1F 1F 1F LINE INPUT (FM Radio) LINE INPUT (Melody Chip) 1F 1F BB (Voice CODEC) Notes: 1. Wolfson recommends using a single, common ground reference. Where this is not possible care should be taken to optimise split ground configuration for audio performance. 2. Supply decoupling capacitors on DCVDD, DBVDD, SPKVDD, HPVDD and AVDD should be positioned as close to the WM8959 as possible. Values indicated are minimum requirements. 3. Capacitor types should be carefully chosen. Capacitors with very low ESR are recommended for optimum performance. 4. The loudspeaker should be connected as close as possible to the WM8959. When this is not possible, filtering should be placed on the speaker outputs close to the WM8959. 5. The 2k2 MICBIAS resistors on each of the MIC inputs are typical values and will be suitable for many electret type microphones. However, it is recommended that engineers refer to individual microphone specifications prior to finalising the value of this component. w PP, May 2008, Rev 3.1 153 WM8959 PACKAGE DIMENSIONS B: 42 BALL W-CSP PACKAGE 3.226 X 3.440 X 0.7mm BODY, 0.50 mm BALL PITCH Pre-Production DM049.C 6 D 2 G A2 A B C e D 5 E F G 2X 0.10 Z 0.10 Z E1 E A 6 5 4 3 2 1 DETAIL 1 4 A1 CORNER DETAIL 2 e D1 2X TOP VIEW BOTTOM VIEW f SOLDER BALL bbb Z f h 1 Z A1 DETAIL 2 Symbols A A1 A2 D D1 E E1 e f g h MIN 0.615 0.225 0.355 Dimensions (mm) NOM MAX 0.7 0.785 0.250 0.275 0.405 0.380 3.226 BSC 2.500 BSC 3.440 BSC 3.00 BSC 0.50 BSC 0.070 0.315 BSC 0.105 NOTE 5 0.060 BSC 0.035 NOTES: 1. PRIMARY DATUM -Z- AND SEATING PLANE ARE DEFINED BY THE SPHERICAL CROWNS OF THE SOLDER BALLS. 2. THIS DIMENSION INCLUDES STAND-OFF HEIGHT ‘A1’ AND BACKSIDE COATING. 3. A1 CORNER IS IDENTIFIED BY INK/LASER MARK ON TOP PACKAGE. 4. BILATERAL TOLERANCE ZONE IS APPLIED TO EACH SIDE OF THE PACKAGE BODY. 5. ‘e’ REPRESENTS THE BASIC SOLDER BALL GRID PITCH. 6. THIS DRAWING IS SUBJECT TO CHANGE WITHOUT NOTICE. 7. FOLLOWS JEDEC DESIGN GUIDE MO-211-C. w PP, May 2008, Rev 3.1 154 Pre-Production WM8959 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 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 PP, May 2008, Rev 3.1 155