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Stereo Digital Volume Control
DESCRIPTION
The WM8816 is a highly linear stereo volume control for audio systems. The design is based on resistor chains with external op-amps, which provides flexibility for the supply voltage, signal swing, noise floor and cost optimisation. The gain of each channel can be independently programmed from -111.5dB to +15.5dB through a digital serial control interface. Audible clicks on gain changes are eliminated by changing gains only when a zero crossing has been detected in the signal. The device also features peak level detection, which can be used for Automatic Gain Control. The WM8816 operates from a single +5V supply and accepts signal input levels up to 18V. The WM8816 is available in a 16-pin SOIC package. It is guaranteed over a temperature range of -20 to +60C.
WM8816
FEATURES
* * * * * * * * Gain range from -111.5dB to +15.5dB 0.5dB Gain step size Total Harmonic Distortion 0.001% (100dB) typical Crosstalk -110dB typical Input signals up to 18V Zero Detection for Gain Changes Hardware and Software Mute Power On/Off Transient Suppression
APPLICATIONS
* * * * Audio Amplifiers Consumer Audio / Entertainment Systems Mixing Desks Audio Recording Equipment
BLOCK DIAGRAM
LFO LIN
LMO LGND
LEFT OUT
Zero Crossing Detector
Peak Level Detector
+
CSB MUTEB DATA CCLK
External Opamps
WM8816
Control
DAC
Zero Crossing Detector
Peak Level Detector
RMO
+
RIGHT OUT
RGND
-
RFO RIN
AVDD
AGND
DVDD
DGND
WOLFSON MICROELECTRONICS plc www.wolfsonmicro.com
Product Preview, 2004, Rev 1.4
Copyright 2004 Wolfson Microelectronics plc
WM8816 TABLE OF CONTENTS
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DESCRIPTION .......................................................................................................1 FEATURES.............................................................................................................1 APPLICATIONS .....................................................................................................1 BLOCK DIAGRAM .................................................................................................1 PIN CONFIGURATION...........................................................................................3 ORDERING INFORMATION ..................................................................................3 PIN DESCRIPTION ................................................................................................3 ABSOLUTE MAXIMUM RATINGS.........................................................................4 RECOMMENDED OPERATING CONDITIONS .....................................................4 ELECTRICAL CHARACTERISTICS ......................................................................5
CONTROL INTERFACE TIMING DIAGRAM ................................................................. 6 REGISTER MAP ........................................................................................................... 8
PERFORMANCE GRAPHS....................................................................................9 RECOMMENDED EXTERNAL COMPONENTS ..................................................10
RECOMMENDED EXTERNAL COMPONENTS VALUES ........................................... 10 APPLICATION RECOMMENDATIONS ....................................................................... 11
PACKAGE DIMENSIONS ....................................................................................12 IMPORTANT NOTICE ..........................................................................................13
ADDRESS: .................................................................................................................. 13
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WM8816
PIN CONFIGURATION
AVDD LMO LFO LIN LGND CSB DVDD MUTEB
1 2 3 4 5 6 7 8
16 15 14 13 12 11 10 9
AGND RMO RFO RIN RGND DGND CCLK DATA
ORDERING INFORMATION
DEVICE XWM8816EDW/V XWM8816GEDW/V TEMPERATURE RANGE -20 to +60oC -20 to +60oC PACKAGE 16-pin SOIC (plastic) Wide 16-pin SOIC Wide MOISTURE SENSITIVITY LEVEL MSL3 MSL3 PEAK SOLDERING TEMPERATURE 240C 260C
PIN DESCRIPTION
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 NAME AVDD LMO LFO LIN LGND CSB DVDD MUTEB DATA CCLK DGND RGND RIN RFO RMO AGND TYPE Supply Analogue Output Analogue Input Analogue Input Analogue Input Digital Input Supply Digital Input Digital In / Out Digital Input Supply Analogue Input Analogue Input Analogue Input Analogue Output Supply DESCRIPTION Supply Voltage for Analogue Circuitry External Op-amp Inverting Input (Left Channel) External Op-amp Feedback Signal (Left Channel) Input Signal (Left Channel) Input Signal Ground (Left Channel) Chip Select (active low) Supply Voltage for Digital Circuitry Mute (active low) Serial Interface Data Input / Output (tri-state) Serial Interface Clock Digital Ground Input Signal Ground (Right Channel) Input Signal (Right Channel) External Op-amp Feedback Signal (Right Channel) External Op-amp Inverting Input (Right Channel) Analogue Ground
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WM8816 ABSOLUTE MAXIMUM RATINGS
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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 susceptible to damage from excessive static voltages. To optimise the distortion and noise performance of pins 3, 4, 13 and 14, the on-chip ESD protection circuitry has been restricted, and consequently only achieves 300V when characterised to the Human Body Model. 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 <30C / 85% Relative Humidity. Not normally stored in moisture barrier bag. MSL2 = out of bag storage for 1 year at <30C / 60% Relative Humidity. Supplied in moisture barrier bag. MSL3 = out of bag storage for 168 hours at <30C / 60% Relative Humidity. Supplied in moisture barrier bag. CONDITION Input signal voltage Positive supply voltage (AVDD to AGND, DVDD to DGND) Input voltage (all other pins) Operating temperature Storage temperature MIN -20V -0.5V -0.5V -40C -55C MAX +20V 6V AVDD + 0.5V 85C 125C
RECOMMENDED OPERATING CONDITIONS
PARAMETER Input signal voltage Positive supply voltage Negative supply voltage Input signal grounds Operating temperature AVDD, DVDD AGND, DGND LGND, RGND -20 SYMBOL TEST CONDITIONS MIN -18 4.5 5 0 0 60 60 TYP MAX +18 5.5 UNIT V V V V C
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WM8816
ELECTRICAL CHARACTERISTICS
TEST CONDITIONS AVDD=5.0V, AGND = 0V, TA = 25C, unless otherwise stated. PARAMETER Analogue Inputs / Outputs Input resistance Input capacitance Input offset voltage (note 1) Supply current Power supply rejection ratio (Note 2) Gain Control Gain range Gain step size Gain error (Note 2) G D DE Lowest gains guaranteed by design, not tested in production. Between channels 113 Gain = 0dB N Gain = -60dB Gain = mute THD+N DNR CR Between channels, gain=0dB, fIN=1kHz All digital inputs All digital inputs ILoad = 2mA ILoad = 2mA DVDD -0.4 1 VIH to VIH VIL to VIL VIL to VIH VIH to VIL 20 100 100 100 Load = 100pF Load = 3.3k 20 200 200 500 500 100 100 0.7 DVDD 0.4 VIN= 1Vrms, gain=0dB, VOUT with OP275, DC to 20 kHz 120 -100 4 2.5 0.001 (100) 130 -110 % (dB) dB dB 13 Vrms -111.5 0.5 0.5 +15.5 dB dB dB RIN CIN Voffset IDD PSRR For any gain For any gain Op-amp gain = -15.5 Op-amp gain = 1 Op-amp gain = 15.5 From AVDD / AGND From AVDD 7 10 2 0.8 3 12 2.5 80 5 k pF mV mV mV mA dB SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
Gain match error (Note 2) Mute attenuation Audio Performance Noise (Note 2) VIN = 0V, VOUT with OP275, A-weighed Total Harmonic Distortion plus Noise Dynamic Range (Note 2) Crosstalk (Note 2) Digital Inputs / Outputs Input low voltage Input high voltage Output low voltage Output high voltage Control Interface Timing Clock Frequency Period of CCLK high Period of CCLK low Rise time of CCLK Fall time of CCLK Hold time, CCLK high to CSB low Setup time, CSB low to CCLK high Setup time, valid DATA to CCLK high Hold time, CCLK high to invalid DATA Setup time, CCLK low to valid DATA Hold time, CSB high or 16th CCLK low to invalid DATA
ME MATT
0.2
dB dB
VIL VIH VOL VOH fCCLK tWHC tWLC tRC tFC tHCSH tSSLCH tSDCH tHCHD tDCLD tDSZ
0.3 DVDD
V V V V MHz ns ns ns ns ns ns ns ns ns ns
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WM8816
TEST CONDITIONS AVDD=5.0V, AGND = 0V, TA = 25C, unless otherwise stated. PARAMETER Hold time, 16th CCLK high to CSB high Setup time, CSB high to CCLK high Note: 1. 2. External MC33078 op-amp. Will vary depending on op-amp input bias current and input offset voltage. Guaranteed by design. SYMBOL tHLCHS tSSHCH TEST CONDITIONS MIN 200 200 TYP MAX
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UNIT ns ns
CONTROL INTERFACE TIMING DIAGRAM
tWLC CCLK tHCSH tSSLCH CSB tSDCH tHCHD DATA (IN) A7 A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 tDCLD DATA (OUT) ADDRESS BYTE D7 D6 D5 D4 D3 D2 D1 D3 D2 D1 D0 tDSZ D0 tHLCHS tSSHCH tWHC tRC tFC
DATA BYTE
Figure 1 Control Interface Timing Diagram
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WM8816
DEVICE DESCRIPTION
The WM8816 is a stereo digital volume control designed for audio systems. The levels of the left and right analogue channels can be programmed independently through the serial interface. The resistor values in the internal resistor chains are decoded to 0.5 dB resolution with multiplexers, giving a gain range of -111.5 to +15.5 dB. The code for -112 dB activates mute for maximum attenuation. The WM8816 has two constant impedance signal inputs. The left channel input is between LIN and LGND, and the right channel between RIN and RGND. The output pins LFO, LMO (left) and RFO, RMO (right) are designed to interface directly to two external op-amps, which produce the volume controlled output signals. This provides flexibility for the supply voltage and signal swing; while the WM8816 runs at 5V, the output signal swing depends solely on the op-amp supply.
INTERFACES
Control information is written into or read back from the internal register via the serial control port. This port consists of a bi-directional data pin (DATA), an active low chip select pin (CSB) and the control clock (CCLK). Control data is shifted into the serial input register on the rising edges of CCLK pulses, while CSB is low. All control instructions require two bytes of data. The first byte contains a 4bit register address and a read/write bit, and the second byte is the control word. CSB must return to high at the end of each word. When reading from the control registers, data is shifted out on the falling edges of CCLK. When CSB is high, the DATA pin is in a high impedance state. In a multi-channel system, the same DATA and CCLK lines can thus be connected to several WM8816 volume controllers, and each device can be independently addressed by pulling its CSB pin low.
OPERATING MODES
When power is first applied, a power-on reset initialises the control registers and mutes the WM8816. To activate the device, the MUTEB pin must be high and a non-zero value must be written to the gain register. After that the device can be muted again either by pulling the MUTEB pin low or by writing zero (00hex) to the gain register.
CHANGING THE GAIN OF THE CHANNEL
The WM8816 has two gain registers for the left and right channels respectively. There is also an alias register address to update both gain registers simultaneously. When a new gain value is written into a gain register the WM8816 will wait until the next falling edge zero crossing in the input signal before changing the gain. This ensures that no audible click is produced at the output. If there are no zero crossings in the signal after 23ms internal delay generators change the gain regardless, right channel followed by the left channel. If both gain registers are changed simultaneously, the gain is changed first on the right and then the left channel. Note: The block diagrams in this datasheet only show a representation of the feedback resistor paths and should be thought of as the exact internal device structure. As the internal structure is different, it is not possible to correlate the measured impedance between input and output, and the actual gain attenuation.
PEAK LEVEL DETECTION
The WM8816 has an on-chip 8-bit digital-to-analogue converter (DAC) used for monitoring the peak level of the output signal. The DAC input value is programmed via the serial interface. The reference value VREF is calculated from VREF = k/256 x 18V, where k is the DAC input code. When a positive peak signal level exceeds this value, the peak detector sets Bit 1 (for the left channel) or Bit 0 (right channel) of the status register. These bits remain set until the status register is read.
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WM8816
REGISTER MAP
REGISTER 7 Peak Detector Status R4 X 6 1 ADDRESS BYTE BITS 5 0 4 1 3 1 2 R/W 1 X 0 X MSB...LSB Output code 00000000 00000001 00000010 00000011 Input code 11111111 11111110 11111101 : 00000010 00000001 00000000 Input code 11111111 11111110 11111101 : 11100000 00000010 00000001 00000000 Input code 11111111 11111110 11111101 : 11100000 00000010 00000001 00000000 DATA BYTE
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Function No overload Right overload Left overload Both overload DAC output 255/256 x 18V 254/256 x 18V 253/256 x 18V : 2/256 x 18V 1/256 x 18V AGND Gain dB +15.5 +15.0 +14.5 : 0.0 -111.0 -111.5 mute Gain dB +15.5 +15.0 +14.5 : 0.0 -111.0 -111.5 mute
Peak Detector Reference R3
X
1
1
0
0
R/W
X
X
Left Channel Gain R2
X
1
1
0
1
R/W
X
X
Right Channel Gain R1
X
1
1
1
0
R/W
X
X
Both Channel Gains R5
X
1
0
0
1
W
X
X
Write to both gain registers
Table 1 Register Map Description Notes: 1. 2. 3. Address bit 2 is the read / write bit (1 for read, 0 for write). X represents `do not care' entries. Set to 1 for minimum power consumption. All registers are set to their default value (all zeros) during power-on reset, except R3 which is set to 255.
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WM8816
PERFORMANCE GRAPHS
-70
-80
-90 THD+N (dB) -100
-110
-120 -60
-50
-40
-30
-20
-10
+0
+10
Input Signal Level (dBV)
Figure 2 THD + Noise versus input level at gains of +6dB, 0dB, -6dB, -12dB and mute
+0 -20 -40 d B V -60 -80 -100 -120 -140
5k
10k
15k
20k
25k
30k
Frequency (Hz)
Figure 3 FFT of output signal with 1kHz, 1Vrms sine wave input
+0 -20 -40 d B V -60 -80 -100 -120 -140 5k 10k 15k 20k 25k 30k Frequency (Hz)
Figure 4 FFT of output signal with 10kHz, 1Vrms sine wave input
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WM8816 RECOMMENDED EXTERNAL COMPONENTS
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LFO 3 4 LIN LMO 2 5 LGND -18V + +18V
LEFT CHANNEL INPUT
RFO 14 13 RIN RMO 15 12 RGND -18V + +18V
RIGHT CHANNEL INPUT
WM8816
6 9 10 8 CSB DATA CCLK MUTEB AVDD AGND DVDD DGND 1 16 7 11 C2 C1
+5V DC
Micro Controller
+
C3
Note: Connect signal ground and non-inverting opamp input together on the PCB
Figure 5 Typical Application.
RECOMMENDED EXTERNAL COMPONENTS VALUES
COMPONENT REFERENCE C1 C2 C3 SUGGESTED VALUE 220nF 220nF 10F DESCRIPTION Analogue Supply Decoupling Digital Supply Decoupling General Supply Decoupling
Table 2 Recommended External Components Values
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WM8816
APPLICATION RECOMMENDATIONS
1. For best audio performance, all digital activities should be minimised during analogue signal processing. Special attention should be paid to power and ground decoupling. Decoupling capacitors should be located as close to the WM8816 as possible. A clean analogue power supply should always be used. Damage can be caused to the internal delay generators if AVDD and DVDD supply voltages differ to any degree. The AVDD and DVDD pins must therefore be tied together in all designs. During operation of the hardware MUTEB function between setting mute and then un-mute, the device may either not un-mute or the gain setting after un-mute will be incorrect. It is advised to re-write the gain settings immediately following hardware un-mute to guarantee faultless operation. Voltage greater than 500mV on the digital pins while the device is powered down may prevent successful POR of the device when power is re-applied. It is preferable that all digital pins are pulled low during power up or alternatively ensure that there are no residual voltages held on the digital pins during power down. The WM8816 output offset voltage can vary dependent upon the op-amp used usually with the largest level of offset voltage occurring at +15.5dB gain. Output offset voltage has linear relationship on input bias current and offset voltage amplitudes. Using differing op-amp types causes a large variation in offset voltage. Below is a list of recommended op-amps which are found to give the least offset issues when used with the WM8816. Channel matching is also important factor and not necessarily only the absolute offset value.
2.
3.
4.
5.
DEVICE OP275 MC33078/9 AD8610 LT1793 OP1177 OP277
MANUFACTURER Analog Devices On-Semi/ST Analog Devices Linear Analog Devices BurrBrown
OFFSET IN MV 8.55 28.4 1.49 18.5 0.505 0.228
Table 3 Recommended Op-amps
LFO 3 4 LIN LMO 2 5 + LGND +18V 2K 2K
DAC Balanced Output
WM8816
RFO 14
+18V -18V +18V + 2K + -18V
13
RIN RMO 15
12 RGND
-18V
2K
Figure 6 Configuration for Double Balanced Output (One Channel)
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WM8816 PACKAGE DIMENSIONS
DW: 16 PIN SOICW 7.5mm (0.3") Wide Body, 1.27mm Lead Pitch
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DM019.A
e
B
16
9
E
H
L
1 8
D
h x 45o
A1 -CA
SEATING PLANE
C
0.10 (0.004)
Symbols A A1 B C D e E h H L REF:
Dimensions (mm) MIN MAX 2.35 2.65 0.10 0.30 0.33 0.51 0.23 0.32 10.10 10.50 1.27 BSC 7.40 7.60 0.25 0.75 10.00 10.65 0.40 1.27 0o 8o
Dimensions (Inches) MIN MAX 0.0926 0.1043 0.0040 0.0118 0.0130 0.0200 0.0091 0.0125 0.3465 0.3622 0.0500 BSC 0.2914 0.2992 0.0100 0.0290 0.3940 0.4190 0.0160 0.0500 0o 8o
JEDEC.95, MS-013
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-013, VARIATION = AA. REFER TO THIS SPECIFICATION FOR FURTHER DETAILS.
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WM8816
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, that information being relied on is current. All products are sold subject to the WM terms and conditions of sale supplied at the time 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 failure 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 perform 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 property 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 26 Westfield Road Edinburgh EH11 2QB United Kingdom
Tel :: +44 (0)131 272 7000 Fax :: +44 (0)131 272 7001 Email :: sales@wolfsonmicro.com
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