SSM-2005 [ADI]
Decoder 5.1-Channel Soundfield Generator; 解码器5.1声道声场发生器
| 型号： | SSM-2005 |
| 厂家： | 
ADI |
| 描述： | Decoder 5.1-Channel Soundfield Generator |
| 文件： | 总15页 (文件大小：130K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
® Decoder
a
5.1-Channel Soundfield Generator
SSM2005
PIN CONFIGURATIONS
FEATURES
Generates 5.1-Channel Soundfield from All Stereo Sources
No Pre-Encoding Required
Excellent Decoding of Pre-Encoded Sources
4- or 5-Speaker Operation
48-Lead SSOP
(RS Suffix)
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
1
CENTER OUT
LF OUT
R FILTER IN
R FILTER OUT
L FILTER IN
L FILTER OUT
L OUT
Subwoofer Output
2
Full Bandwidth on All Channels
Optimized Modes for Video and Music
Excellent Surround Image at All Positions
Independent Left and Right Surround Steering
No Surround Channel Delay Required
Built-In White Noise Generator
3
RF OUT
4
LS OUT
5
RS OUT
6
NOISE IN
NOISE OUT
L OUT A
7
L IN
8
R OUT
LOAD
9
RESET
DATA IN
R OUT A
R IN
APPLICATIONS
Home Theater Receivers
VCD/DVD Players
Auto Sound Receivers and Amplifiers
Surround Sound Decoders
Karaoke
Computer Audio Boards
Video Games
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
V
V
CC
EE
SSM2005
TOP VIEW
(Not to Scale)
ACOM AUDIO GND
GND
ACOM AUDIO GND
GND
V
V
EE
CC
(L+R) OUT
(L–R) OUT
WRITE
33 CLOCK IN
32 FRONT/REAR TC FILTER
31 LOW BAND TC FILTER
30 HIGH BAND TC FILTER
29 FRONT/REAR DET.
(L–R) HIGH IN
(L–R) LOW IN
GENERAL DESCRIPTION
R HIGH BAND DET.
L HIGH BAND DET.
HIGH BAND DET. OUT
R LOW BAND DET.
L LOW BAND DET.
LOW BAND DET. OUT
The SSM2005 Circle Surround® decoder produces true 5.1-channel
surround soundfield from any stereo source, including VCD, DVD,
VCR, CD and FM stereo broadcasts. The SSM2005 is also compat-
ible with encoded sources, such as Dolby ProLogic® and Circle
Surround encoded movies and music. External delays and noise
reduction processors are not required for the surround channels.
28 FRONT/REAR (L–R) DET.
27 FRONT/REAR (L+R) DET.
26 AUTOBALANCE LOCKOUT
25 AUTOBALANCE TC
Circle Surround encoded stereo signals will produce a full 360º
soundfield when played through the SSM2005. Recording engi-
neers can encode sounds to any of the five speakers surrounding
the listener. Left Front, Right Front, Center, and differentiated
Left and Right surround channels are generated, providing a realis-
tic ambiance effect with either 4- or 5-speaker configurations.
INPUTS
OUTPUTS
LEFT
LEFT
ANALOG
SIGNAL
PROCESSING
RIGHT
STEERING MATRIX
AND OUTPUT
AMPLIFIERS
CENTER
RIGHT
LEFT
SURROUND
RIGHT
SURROUND
The SSM2005 is available from Analog Devices, subject to the
License and Royalty requirements as described on the following
page of the data sheet.
L+R FOR
SUBWOOFER
STEERING
CONTROL
GENERATOR
MODE CONTROL
LOGIC AND NOISE
GENERATOR
RESET
SERIAL BUS
Figure 1. Simplified Block Diagram
and
are registered trademarks of SRS Labs, Inc. and ValenceTechnology Ltd.
Circle Surround is a registered trademark of SRS Labs, Inc. and Valence Technology Ltd.
Dolby ProLogic is a registered trademark of Dolby Laboratories Licensing Corporation, San Francisco, California.
Circle Surround technology is protected under one or more of the following U.S. Patents and corresponding patents
worldwide: 5,319,713; 5,333,201; 5,638,452; 5,771,295.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 1999
SSM2005–SPECIFICATIONS
(VS = ±6.0 V, TA = ؉25؇C, f = 2 kHz, Modes: Video, 5-2-5, Center On, Sound Spread Off,
Autobalance Off, Noise Off)
ELECTRICAL CHARACTERISTICS
Parameter
Symbol
Conditions
Min
Typ Max
Units
INPUT CHARACTERISTICS
Level1
Input Impedance
VL, VR
ZIN
ZSOURCE < 10 Ω
L and R Inputs
0
10
dBd
kΩ
OUTPUT CHARACTERISTICS
Level
Left Front
Right Front
Center
LT = 0 dBd, RT = Off
RT = 0 dBd, LT = Off
LT = RT = 0 dBd, In Phase,
Video Mode
0
0
dBd
dBd
+6
+3
dBd
dBd
Left Rear, Right Rear
Channel Separation
LT = RT = 0 dBd, Out of Phase
Left Front and Right Front / Center
Left Rear and Right Rear / Center
Left Rear, Left Front
Left Rear, Right Rear
Output Impedance
LT = RT, In Phase, Video Mode
LT = RT, Out of Phase
LT = RT, Out of Phase
30
40
30
30
10
dBd
dBd
dBd
dBd
Ω
LT = RT, Out of Phase
ZOUT
DYNAMIC PERFORMANCE
Total Harmonic Distortion + Noise
Signal-to-Noise Ratio
Dynamic Range, Output
Headroom
THD+N
SNR
DR
All Channels
0.04
88
100
12
%
dB
dB
dB
Noise Floor to 1% THD
All Channels
HR
NOISE GENERATOR
Output Level2
Matching
Noise Mode On, A-Weighted
All Channels
–10
dBd
dB
0.5
±4
5
1.5
AUTOBALANCE
Capture Range
|
| – |
|
dB
s
VH
VL
Capture Time
VL = VR > –10 dBd,
|VLEFT – VRIGHT| < 3 dB
CONTROL LOGIC
Logic Thresholds
High (1)
Low (0)
Input Current
Timing Characteristics
Logic Levels Referenced to ACOM
See Timing Diagrams
2.4
V
V
µA
0.8
1
POWER SUPPLIES
Operating Voltage Range3
VS
+VS, –VS
IS
Single Supply
Dual Supply
VL = VR = ACOM, VS = 12 V
+10
±5
+12
±6
30
V
V
mA
Current
18
NOTES
10 dBd = 300 mV rms.
2With filter shown in Figure 8.
3Specifications apply for VS = ± 6 V.
Specifications subject to change without notice.
LICENSING INFORMATION
TheCIRCLESURROUND® TECHNOLOGYrightsincorporatedintheSSM2005areownedbySRSLabs, Inc. andbyValenceTechnologyLtd., andlicensed
to Analog Devices, Inc.
Users of any SSM2005 Circle Surround decoder must first sign a free use license to purchase OEM quantities for consumer electronics applications which
may be granted upon submission of a preproduction sample to, and the satisfactory passing of performance verification tests performed by SRS Labs, Inc.
or Valence Technology Ltd. SRS Labs, Inc. and Valence Technology Ltd. reserve the right to decline a use license for any submission that does not pass
performance specifications or is not in the consumer electronics classification.
All equipment manufactured using any SSM2005 Circle Surround decoder must carry the Circle Surround logo on the front panel in a manner approved
in writing by SRS Labs, Inc. or Valence Technology Ltd. If the Circle Surround logo is printed in users manuals, service manuals or advertisements, it
must appear in a form approved in writing by SRS Labs, Inc. or Valence Technology Ltd. The rear panel of Circle Surround products, users manuals,
service manuals, and all advertisements must all carry the Circle Surround legend as specified in the Circle Surround trademark manual published by SRS
Labs, Inc. and Valence Technology Ltd.
–2–
REV. 0
SSM2005
ABSOLUTE MAXIMUM RATINGS*
1
Package Type
Units
JA
JC
Supply Voltage, VS . . . . . . . . . . . . . . . . . . . . . . ±8 V or +16 V
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VS
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Operating Temperature Range . . . . . . . . . . . –20°C to +70°C
Junction Temperature Range . . . . . . . . . . . . . . . . . . . .+150°C
Lead Temperature Range (Soldering, 60 sec) . . . . . . .+300°C
48-Lead SSOP (RS)
100
50
°C/W
NOTE
1θJA is specified for worst case conditions.
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum rating condi-
tions for extended periods may affect device reliability.
ORDERING GUIDE
Temperature
Range
Package
Description
Package
Option
Model
SSM2005RS-Reel
–20°C to +70°C
48-Lead SSOP
RS-48
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the SSM2005 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. 0
–3–
SSM2005–Typical Performance Characteristics
10
10
V
V
R
= ±6V
= 300mV rms
= 100k⍀
V
V
R
= ±6V
= 1kHz
= 100k⍀
SY
IN
SY
IN
L
L
0dBr = 300mV rms
1
1
LF, RF OUT
0.1
0.1
0.01
CENTER OUT
LF, RF OUT
CENTER OUT
5
0.01
20
100
1k
FREQUENCY – Hz
10k 20k
؊35
؊25
؊15
؊5
15
AMPLITUDE – dBr A
Figure 2. THD + N vs. Frequency; Front Channels
Figure 4. THD + N vs. Amplitude; Front Channels
10
10
V
L
R
= ±6V
V
V
R
= ±6V
= 300mV rms
= 100k⍀
SY
SY
IN
= R = 1kHz; OUT OF PHASE
T
= 100k⍀
T
L
L
0dBr = 300mV rms
1
1
LS, RS OUT
0.1
0.1
LS OUT
RS OUT
0.01
؊35
0.01
؊25
؊15
؊5
20
100
1k
10k 20k
5
15
FREQUENCY – Hz
FREQUENCY – dBr A
Figure 3. THD + N vs. Frequency; Surround Channels
Figure 5. THD + N vs. Frequency; Surround Channels
–4–
REV. 0
SSM2005
PIN CONFIGURATIONS
48-Lead SSOP
(RS Suffix)
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
1
CENTER OUT
LF OUT
R FILTER IN
R FILTER OUT
L FILTER IN
L FILTER OUT
L OUT
2
3
RF OUT
4
LS OUT
5
RS OUT
6
NOISE IN
NOISE OUT
L OUT A
7
L IN
8
R OUT
LOAD
9
RESET
DATA IN
R OUT A
R IN
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
V
V
CC
EE
SSM2005
TOP VIEW
(Not to Scale)
ACOM AUDIO GND
GND
ACOM AUDIO GND
GND
V
V
EE
CC
(L+R) OUT
(L–R) OUT
WRITE
33 CLOCK IN
32 FRONT/REAR TC FILTER
31 LOW BAND TC FILTER
30 HIGH BAND TC FILTER
29 FRONT/REAR DET.
(L–R) HIGH IN
(L–R) LOW IN
R HIGH BAND DET.
L HIGH BAND DET.
HIGH BAND DET. OUT
R LOW BAND DET.
L LOW BAND DET.
LOW BAND DET. OUT
28 FRONT/REAR (L–R) DET.
27 FRONT/REAR (L+R) DET.
26 AUTOBALANCE LOCKOUT
25 AUTOBALANCE TC
REV. 0
–5–
SSM2005
PIN FUNCTION DESCRIPTION
Connected to / Function:
Pin #
Name
1
2
3
4
R Filter In
R Filter Out
L Filter In
L Filter Out
L Out
3-Pole Active Low-Pass Filter Output; used for Center Cancelling Correction
3-Pole Active Low-Pass Filter Input
3-Pole Active Low-Pass Filter Output; used for Center Cancelling Correction
3-Pole Active Low-Pass Filter Input
Connect to Pin 6
5
6
7
8
L Out A
L In
R Out
Connect to Pin 5
Left Stereo Source Line Input; Should be 0 dBd (300 mV rms)
Connect to Pin 9
9
R Out A
R In
VEE
ACOM Audio GND
GND
VCC
(L+R) Out
(L–R) Out
(L–R) High In
(L–R) Low In
R High Band Det.
L High Band Det.
High Band Det. Out
R Low Band Det.
L Low Band Det.
Low Band Det. Out
Autobalance TC
Autobalance Lockout
Front/Rear (L+R) Det.
Front/Rear (L–R) Det.
Front/Rear Det.
High Band TC Filter
Low Band TC Filter
Front/Rear TC Filter
Clock In
WRITE
VEE
GND
ACOM Audio GND
VCC
Data In
Reset
LOAD
Noise Out
Noise In
RS Out
LS Out
RF Out
LF Out
Center Out
Connect to Pin 8
Right Stereo Source Line Input; Should be 0 dBd (300 mV rms)
Negative Supply
Audio Ground
Power Ground
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Positive Supply
RC to Front/Rear Detector Input
RC to Front/Rear Detector Input and Input of Crossover
Output of High-Pass Crossover
Output of Low-Pass Crossover
RC Network Fed by Right Stereo Source Line Input
RC Network Fed by Left Stereo Source Line Input
Capacitor to ACOM; Controls Rear High Frequency Output Steering
Right Input, used for Autobalance and Low Band Steering
Left Input, used for Autobalance and Low Band Steering
Capacitor to ACOM; Controls Left-to-Right Output Steering
RC Network to ACOM
RC Network to ACOM
RC Network Fed by (L+R) Out (Pin 15)
RC Network Fed by (L-R) Out (Pin 16)
Capacitor to ACOM; Controls Front-to-Back Output Steering
RC Network to ACOM
RC Network to ACOM
RC Network to ACOM
Clock from Serial Bus
Chip Select from Serial Bus
Negative Supply
Power Ground
Audio Ground
Positive supply
Data from Serial Bus
Reset from Serial Bus
Load from Serial Bus
Connect to RC Filter; White Noise Output
Connect to RC Filter Output; Filtered White Noise
Connect to Right Surround (Rear) Amplifier Input
Connect to Left Surround (Rear) Amplifier Input
Connect to Right Front Amplifier Input
Connect to Left Front Amplifier Input
Connect to Center Amplifier Input
–6–
REV. 0
SSM2005
Table I. Abbreviations and Notations Used in the Text
L
R
LT
RT
Left
Right
LF
RF
LS
RS
Left Front Output
C
dBd
ACOM
VCA
Center Output
0 dBd = 300 mV rms
Quality Audio Ground
Voltage Controlled Amplifier
Right Front Output
Left Surround Output
Right Surround Output
Surround Encoded Left Input
Surround Encoded Right Input
SIMPLIFIED THEORY OF OPERATION
General
Output Amplifier
The Output Amplifiers receive signals from the VCAs and the
internal Noise Generator. Each amplifier has a multiplexer switch
which will enable it to output a white noise waveform under
control of the Serial Bus. This simplifies balancing of the listening
system. The output amplifiers provide load drive capability with
typically 12 dBd of headroom. The overall gain from L and R
inputs to Circle Surround Outputs is unity; the Noise Generator
gives an output level of –10 dBd (100 mV rms).
The SSM2005 Circle Surround decoder processes stereo input
signals, and outputs 5 channels of surround sound, plus an L+R
output for a subwoofer low-pass filter. The SSM2005 provides
signal processing, steering control, input autobalance, and a digital
interface for mode control. This device uses analog circuits such as
amplifiers, rms detectors, VCAs and digital logic to carry out the
circle surround algorithm in real time. No artificial reverberation
or delay effects are used, preserving the natural sound of the
original stereo recording.
Mode Control Logic
The various SSM2005 modes are shown in Figure 7. There are
modes for different types of source material, such as video sound
tracks or music. Other modes include 5.2.5/4.2.4, Sound Spread,
Phantom Center mode, autobalance, and Noise Generation. Each
mode’s status is stored in the Mode Control Logic, as determined
by the data sent via the serial bus. Refer to the Typical Outputs In
Various Modes section for a more detailed explanation of the vari-
ous modes.
The SSM2005 can decode any existing media including CD,
VCD, DVD, cassette tapes, VHS, FM radio and television stereo
broadcasts. For convenience in balancing the system, an on-chip
digital noise generator is available. The net result is outstanding
5.1 channel surround sound from all stereo sources, which re-
veals the hidden ambiance already contained in existing music
and cinematic recordings. The listening experience is greatly
enhanced and made more enjoyable when compared to ordinary
stereo. In the following description, please refer to Figure 6.
Applying a logic low to the Reset input will override the Mode
Control Logic and put the SSM2005 into its Default mode. De-
fault modes for the device are video/5.2.5/center active/sound
spread on/autobalance on/noise off. See Figure 9 for logic timing
diagrams.
Input Signal Processing
Stereo inputs L and R are fed to both the Steering Control
Generator, and the Autobalance circuitry. The balanced signals
are passed through the Center Channel Cancel circuitry to the
Channel Steering VCAs.
Autobalance Feature
The autobalance circuitry is activated when the SSM2005 is placed
into autobalance On Mode. In this mode, the device will adjust the
gains of its input amplifiers to balance the stereo inputs to equal
loudness. With a mono input signal, the autobalance circuitry will
typically balance L and R to within ±0.5 dB. A 22 µF external ca-
pacitor connected to Pin 25 sets a 5 second averaging period for
comparing the levels between the stereo inputs.
The autobalance output signals also feed the Precision Sum and
Difference Amplifiers. The sum (L+R) and difference (L–R)
signals form the basis for the center and surround channels,
respectively. The center channel signal is fed to the center chan-
nel cancel circuitry, and to the channel steering VCAs. The
surround channel signal is separated by an external Crossover
Network into the Surround High and Surround Low bands and
fed to the channel steering VCAs.
Using autobalance will slightly degrade the maximum channel
separation from the SSM2005. The autobalance mode can be
left off without fear of degrading the soundfield, unless the
stereo input signal is expected to be off balance by more than
±1.5 dB. Most CD, VCD and DVD player outputs are specified
to within ±0.25 dB balance.
Steering Control Generator
The purpose of the steering control generator is to analyze the dy-
namic characteristics of music, dialog, or special effects, using pro-
prietary high speed analog computing circuits. Control voltages for
all VCAs are then computed, and the soundfield expansion per-
formed in accordance with the circle surround decoding algorithm.
The control signals depend upon the SSM2005 modes selected, and
will differ for video mode vs. music mode, 5.2.5 mode vs. 4.2.4
mode, etc.
Noise Generator
When the noise mode is selected, the audio inputs are muted.
Noise will be available from the output of the channel determined
by the mode control logic. The noise generator uses a feedback
shift register that generates a pseudo-random digital output wave-
form with a repeat time of three seconds. This digital noise wave-
form is band-pass filtered externally to approximate white noise.
Channel Steering VCAs
Command signals from the steering control generator are fed to
the channel steering VCAs, which control the amplitude of the
five output channels. High performance, low distortion VCAs
with typically 12 dBd headroom are used for all channels.
Power Supplies
The SSM2005 may be operated from regulated ±5 V to ±6 V
supplies that can supply 45 mA each. The recommended operating
voltage is ± 6 V, which will give a typical headroom of 12 dBd.
REV. 0
–7–
SSM2005
Power-Up
The shift register clock at CLOCK IN is enabled when the
WRITE input is low. The WRITE pin can therefore be used as a
chip select input. However, the shift register contents are not
transferred into the register banks until the rising edge of LOAD.
For a traditional 3-wire serial interface, WRITE and LOAD
should be tied together. Figure 7 shows the timing diagram and
minimum timing requirements for the digital interface.
The SSM2005 will be in an undefined mode on power-up. Reset
should be applied to the SSM2005, or the mode control logic
should be loaded to put the device into a definite mode state.
Serial Data Control Inputs
The SSM2005 provides a simple 3- or 4-wire serial interface to
control the mode settings for the device. Data is input on the
DATA IN pin, while CLOCK IN is the serial clock. Data can be
shifted into the SSM2005 at clock rates up to 1 MHz.
To enable a data transfer, the WRITE and LOAD inputs are
driven low. The 8-bit serial data, formatted MSB first, should
be fed to DATA IN and clocked into the shift register on the
rising edge of CLOCK IN. The new mode setting will then
activate on the rising edge of WRITE and LOAD.
CIRCLE
SURROUND
OUTPUTS
STEREO
INPUTS
LEFT
RIGHT
L
L
CENTER CHANNEL
CANCEL
AUTO BALANCE
AND MUTE
R
R
AMPLIFIERS
CENTER
OUTPUT
C
AMPLIFIERS
CHANNEL
L+R = CENTER
PRECISION
SUM AND
STEERING
VCAs
SURROUND
HIGH BAND
DIFFERENCE
AMPLIFIERS
L–R = SURROUND
L
S
CROSSOVER
NETWORK
R
S
SURROUND
LOW BAND
STEERING CONTROL GENERATOR
MODE CONTROL LOGIC
7X
NOISE
GENERATOR
TO SUBWOOFER
FILTER
RESET
CLOCK
DATA
SERIAL BUS
+V GND ؊V ACOM
SELECT
LOAD
INPUT POWER
Figure 6. Block Diagram
Table II. Modes List
Modes
Effect
Center Channel Cancellation Active
Center Cancel Cancellation Off; Center Reduced by –4 dB.
Video
Music
5-2-5
4-2-4
5-Channel Circle Surround Enabled
4-Channel Matrix Enabled
Center On
Phantom Center
Center Channel Output On
Center Channel Output Off; Divided and Added to LF and RF
Sound Spread On
Sound Spread Off
Hard Panned Input Steered to Front and Rear Side
Hard Panned Input Steered to Front Side Only
Autobalance On
Autobalance Off
Balances L and R to ±1 dB
Autobalance Disabled
Noise Off
Noise On
Noise Generator Disabled
Noise Generator On; Inputs Muted
–8–
REV. 0
SSM2005
Table III. Data Decoding Truth Table
LSB
MSB
D0
Reset
D1
D2
D3
D4
D5
D6
D7
Mode
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
1
1
0
1
0
1
1
1
1
1
1
1
1
1
1
X
0
0
1
1
0
0
1
1
1
1
1
1
1
1
1
1
X
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
1
X
X
X
X
X
X
X
1
X
X
X
X
X
X
X
X
1
X
X
X
X
X
X
X
X
X
X
1
X
X
X
X
X
X
X
X
X
X
X
X
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1
C Noise On
LF Noise On
RF Noise On
LS Noise On
RS Noise On
All Mute
Autobalance On
Autobalance Off
Center Active
Phantom Center
Sound Spread On
Sound Spread Off
5.2.5 Mode
4.2.4 Mode
Video Mode
Music Mode
Noise Off, Autobalance On, Center Active,
Sound Spread On, 5.2.5 Mode, Video Mode
0
X
X
X
X
X
X
X
X
X
0
X
X
X
X
X
X
X
0
X
X
X
X
X
0
X
X
X
0
X
REV. 0
–9–
SSM2005
Table IV. Timing Description
Timing Symbol
Description
Min
Typ
Max
Units
tCL
tCH
tDS
tDH
tCW
tWC
tLW
tWL
tL
Input Clock Pulsewidth
Input Clock Pulsewidth
Data Setup Time
Data Hold Time
Positive CLK Edge to End of Write
Write to Clock Setup Time
End of Load Pulse to Next Write (4-Wire Mode)
End of Write to Start of Load (4-Wire Mode)
Load Pulsewidth (4-Wire Mode)
Load Pulsewidth (3-Wire Mode)
50
50
25
35
25
35
20
20
250
250
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
tW3
NOTES:
1. An idle HI (CLK-HI) or idle LO (CLK-LO) clock may be used. Data is latched on the positive edge.
2. For SPITM or MICROWIRETM 3-wire bus operation, tie LD to WRITE and use WRITE pulse to drive both pins. (This generates an automatic
internal LD signal.)
3. If an idle HI clock is used, tCW and tWL are measured from the final negative transition to the idle state.
4. The first data byte selects an address (MSB HI), and subsequent MSB LO states set gain levels. Refer to the Address/Data Decoding Truth Table.
5. Data must be sent MSB first.
1
CLK
0
1
D7
D6
D5
D4
D3
D2
D1
D0
DATA
0
1
WRITE & LOAD
0
tCL
tCH
1
0
CLK
tDH
tDS
1
0
DATA
tCW
tW3
tWC
1
0
WRITE & LOAD
Figure 7. Logic Timing Diagram
SPI is a trademark of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corporation.
–10–
REV. 0
SSM2005
TYPICAL OUTPUTS IN VARIOUS MODES
Table VI. Video/5.2.5/Sound Spread ON/Center ON
The SSM2005 Circle Surround decoder uses ambiance and
directional information already present in a stereo signal, and
does not require the audio signal to be encoded. The device
requires no delay generators or noise reduction. Fully differenti-
ated rear channels provide rear stereo separation for enhanced
spatial perception, a feature unique to Circle Surround.
Input
|LT| – |RT|
Output
(dB)
dB Є φ
|LF|
|RF|
|C|
|LS|
|RS|
0 Є 0°
– 30
–35
0
–60
0
–30
–35
–60
0
–15
–36
+6
–40
+6
0
–30
0
–40
+6
–30
0
–25
–15
0 Є 180°
LT Only
RT Only
–6 Є 0°
–6 Є 180°
–45
–30
–30
–4
Video mode provides the highest degree of channel separation
between the front and center speakers. Video mode cancels com-
mon center channel material from the left and right front chan-
nels. This restores a wide stereo image to matrix encoded sound
tracks, while maintaining a solid center channel for dialogue and
mono information.
–30
–26
0
Table VII. Music/5.2.5/Sound Spread ON/Center ON
The Music mode is optimized for unencoded stereo music repro-
duction, with full bandwidth on all channels. The steering for the
LF and RF channels is deactivated to prevent any stereo image
wandering. The independent two-band rear channel steering
provides excellent surround imaging, even in car audio applica-
tions. Well balanced sound is obtained everywhere within a 4- or
5-speaker setup.
Input
|LT| – |RT|
Output
(dB)
dB Є φ
|LF|
|RF|
|C|
|LS|
|RS|
0 Є 0°
0
0
0
–60
0
0
0
0
–60
0
–6
–6
+2
–40
+6
0
–30
0
–40
+6
–30
0
–25
–15
0 Є 180°
LT Only
RT Only
–6 Є 0°
–6 Є 180°
–45
–30
–30
–4
The 5.2.5 mode provides the maximum channel separation to
the surround channels, and should be used with any encoded
stereo input signal. The 4.2.4 mode can be used to reduce the
dynamic steering of the surround channels, allowing the
SSM2005 to simulate a 4-channel surround sound decoder.
–26
0
Sound Spread OFF allows the maximum channel separation
between the surround and front speakers. With Sound Spread
OFF, a hard panned left input signal will produce an output
only in the left front output. In Sound Spread ON mode, a hard
panned left input signal will produce equal output from the left
front and left surround outputs.
Table VIII. Video/5.2.5/Sound Spread ON/Phantom Center
Input
|LT| – |RT|
Output
(dB)
dB Є φ
|LF|
|RF|
|C|
|LS|
|RS|
0 Є 0°
+3
–35
0
–60
0
+3
Off
Off
Off
Off
Off
Off
–40
+6
0
–30
0
–40
+6
–30
0
–25
–15
The following tables demonstrate the differences between the
modes of the SSM2005 under various input conditions. The LT
and RT inputs are at 2 kHz, and are shown in terms of their
differences in magnitude (in dB) and phase (in degrees). For
example, a 0 Є 180° input means LT is exactly equal in magni-
tude, but opposite in phase to RT.
0 Є 180°
LT Only
RT Only
–6 Є 0°
–6 Є 180°
–35
–60
0
–15
–36
–30
0
Table V. Video/5.2.5/Sound Spread OFF/Center ON
Table IX. Video/4.2.4/Sound Spread OFF/Center ON
Input
|LT| – |RT|
Output
(dB)
Input
|LT| – |RT|
Output
(dB)
dB Є φ
|LF|
|RF|
|C|
|LS|
|RS|
dB Є φ
|LF|
|RF|
|C|
|LS|
|RS|
0 Є 0°
– 30
–35
0
–60
0
–30
–35
–60
0
–15
–36
+6
–40
+6
–30
–35
–25
0
–40
+6
–35
–30
–30
–15
0 Є 0°
– 30
–35
0
–60
0
–30
–35
–60
0
–15
–36
+6
–40
+6
–32
–32
–26
0
–40
+6
–32
–32
–26
–2
0 Є 180°
LT Only
RT Only
–6 Є 0°
–6 Є 180°
–45
–30
–30
–4
0 Є 180°
LT Only
RT Only
–6 Є 0°
–6 Є 180°
–45
–30
–30
–4
–30
–26
–30
–26
REV. 0
–11–
SSM2005
0.01F
5.9k⍀
0.1F
48.7k⍀
105k⍀
10F
SSM2275-A
4.7nF
1
2
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
C
OUT
+
LF
OUT
10F
0.01F
3
RF
LS
5.9k⍀
0.1F
OUT
+
4
48.7k⍀
OUT
105k⍀
0.1F
100⍀
SSM2275-B
5
4.7nF
RS
OUT
0.47F
6
10F
+
3.82k⍀
7
LEFT IN
1F
33.2k⍀
0.1F
100⍀
8
LOAD
9
RESET
10F
+
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
RIGHT IN
DATA
؉6V
؊6V
؉6V
0.1F
0.1F
SSM2005
؊6V
WRITE
40.2k⍀
274k⍀
0.1F
CLK IN
10F
+
0.1F
100k⍀
1F
0.22F
1F
1nF
1nF
10F
SSM2275-A
+
787⍀
162k⍀
0.01F
787⍀
7.87k⍀
274k⍀
0.1F
1F
787k⍀
100pF
909⍀
0.22F
0.1F
1F
1k⍀
SSM2275-B
0.1F
0.1F
0.1F
909⍀
1F
453⍀
453⍀
0.1F
1F
1F
DENOTES CONTROL
GROUND
453⍀
0.1F
453⍀
1k⍀
+
22F
4.7M⍀
1F
10k⍀
DENOTES SIGNAL
GROUND
1F
DENOTES CONNECTION
L ؉ R OUT
TO SUBWOOFER FILTER
(OPTIONAL)
Figure 8. Typical Application Schematic
–12–
REV. 0
SSM2005
APPLICATION NOTES
SSM2005*
OUTPUTS
10F
10F
Figure 8 shows a typical SSM2005 application schematic. The
stereo source signal is connected to the SSM2005 audio signal
inputs at Pins 7 and 10, as well as the Left/Right level detectors
at Pins 19, 20, 22, and 23. The input signal goes through the
autobalance circuitry and can be accessed at Pins 6 and 9.
A sum (L+R) and difference (L–R) signal is available at Pins 15
and 16, respectively. These signals are fed into the Front/Rear
level detector at Pins 27 and 28.
7
CENTER
48
LEFT IN
47
46
45
44
L
F
10
R
RIGHT IN
F
S
L
R
S
39
SUBWOOFER
1F
2.05k⍀
4.23k⍀
The L+R signal is also fed internally to the center channel VCA
to produce the center channel output at Pin 48. In addition, the
L–R signal is fed into two external filters, creating a low-band and
high-band signal with a crossover frequency of 2 kHz. The cross-
over filters are both 3rd order Bessel filters, providing a minimum
group delay to the surround channels. The L–R high-band signal
is connected to Pin 17, and the L–R low-band signal is connected
to Pin 18. These two pins provide the multiband steering to the
two surround outputs.
0.47F
SSM2275
= 100Hz
*ADDITIONAL PINS
OMITTED FOR CLARITY
f
C
Figure 9. Adding a Subwoofer Output
Implementing a Stereo Bypass Mode
Figure 10 shows a schematic for implementing a clickless stereo
bypass around the SSM2005. The stereo bypass mode allows
the user to defeat the Circle Surround decoding and listen to
two-channel stereo from the left front and right front speakers.
Low-pass filters are inserted between Pins 1 and 2, and Pins 3
and 4. These filters are used for the center-canceling circuitry,
which removes center channel information from the left front
and right front outputs. This circuitry is only active in Video
mode, providing maximum channel separation between the
center and front outputs. In an application that will only use
Music mode, these active filters can be removed and replaced
with a 1 µF capacitor between Pins 1 and 2, and Pins 3 and 4.
The SSM2402 is a clickless dual audio single-pole single-throw
(SPST) switch. When the control voltage, VBYP, is low (below
+0.8 V) the switch is open, and the five channel outputs are
connected to the outputs of the SSM2005. When VBYP goes
high (above +2.0 V) the SSM2402 switch closes, connecting the
LF and RF outputs to Left In and Right In respectively. At the
same time, a data byte should be loaded into the SSM2005,
placing the Circle Surround decoder into Mute Mode. The data
byte required for Mute Mode can be found in Table III, and the
logic timing diagrams can be found in Figure 7.
The capacitors and resistors connected to Pins 21, 24, 25, 26, 29,
30, 31 and 32 are used to create the time constants for the steer-
ing circuitry. The values shown in Figure 8 are strongly recom-
mended. Variation from these values will result in improper
operation of the Circle Surround decoder, and may result in the
assembled unit failing SRS Labs approval.
The noise generator output is at Pin 42, and the input to the noise
steering circuit is at Pin 43. The R-C network connected between
Pins 42 and 43 is used to remove dc voltage and high frequencies,
which could damage speakers. Other noise-shaping circuitry could
be used here to create noise patterns other than white, or to further
attenuate the noise output with a resistor divider.
+6V
SSM2402
1
2
3
4
5
6
7
14
13
12
11
10
9
V
BYP
V
HIGH =
BYP
STEREO MODE
Adding a Subwoofer Output
V
LOW = CIRCLE
SURROUND MODE
BYP
The SSM2005 provides an output of the summed Left In and
Right In signals. This L+R signal is used to drive the center chan-
nel output, and it can also be used to provide a subwoofer chan-
nel by connecting the output from Pin 15 to a low-pass filter. The
schematic for such a configuration is shown in Figure 9.
8
؊6V
SSM2005*
OUTPUTS
CENTER
10F
10F
Here, Pin 15 is connected to a 2nd order Bessel low-pass filter.
The circuit uses the SSM2275, a low noise audio op amp that
can run from the same ±6 V that power the SSM2005. Using
the component values shown in Figure 9, the filter’s cutoff
frequency is 100 Hz.
LEFT IN
7
48
47
46
45
44
L
F
10
39
RIGHT IN
R
F
S
L
R
S
DATA IN
*ADDITIONAL PINS
OMITTED FOR CLARITY
V
LOW = CS MODE
0 0 0 x x x xx
BYP
x DENOTES A DON'T CARE BIT
Figure 10. Implementing a Clickless Stereo Bypass Mode
REV. 0
–13–
SSM2005
Using the SSM2005 for Karaoke
10k⍀
+6V
2.2k⍀
In Video mode, the SSM2005 removes centered vocal informa-
tion from the LF and RF speakers. This allows the device to be
used in Karaoke applications, where the user can sing along with
any music recording. Figure 11 shows a circuit diagram for such
an application.
+6V
0.1F
1k⍀
MIC
+5V
OP179
+6V
؊6V
SSM2402
The OP179 is the microphone preamplifier with a gain of +20 dB.
A 2.2 kΩ resistor connects the microphone to the +6 V supply rail,
providing proper biasing for an electret microphone.
CIRCLE
SURROUND
MODE
1
2
3
4
5
6
7
14
13
12
11
10
9
7404
SW-2
KARAOKE
MODE
The SSM2402 is used as a clickless switch, connecting the
center output to either the center out from the SSM2005 or the
microphone. In Circle Surround mode, the control voltages to
the SSM2402 connect the output from the SSM2005 to the
center output.
8
SSM2005*
In Karaoke Mode, this connection is opened, and the micro-
phone is directed to the center output. At the same time, the
SSM2005 should be loaded with data byte (MSB first):
1 1 1 0 1 0 1 1. This activates the center canceling circuitry in
the SSM2005, removing centered vocal information from the
left front and right front speakers.
؊6V
OUTPUTS
CENTER
10F
10F
48
7
LEFT IN
47
46
45
44
L
F
10
RIGHT IN
R
F
S
L
R
S
The overall result is the microphone output comes out of the
center speaker, with the vocals-removed music coming from the
remaining speakers.
39
FOR KARAOKE, LOAD DATA
BYTE: 1 1 1 0 1 0 1 1
*ADDITIONAL PINS OMITTED
FOR CLARITY
Figure 11. Using the SSM2005 for Karaoke
–14–
REV. 0
SSM2005
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
48-Lead SSOP
(RS Suffix)
0.630 (16.00)
0.620 (15.75)
25
48
0.299 (7.59)
0.292 (7.42)
0.410 (10.41)
0.400 (10.16)
1
24
PIN 1
0.110 (2.79)
0.095 (2.41)
0.092 (2.34)
0.088 (2.24)
8؇
0؇
0.0135 (0.343)
0.008 (0.203)
0.025 (0.635)
BSC
0.040 (1.02)
0.024 (0.61)
0.016 (0.41)
0.008 (0.20)
SEATING
PLANE
0.010 (0.254)
0.005 (0.127)
REV. 0
–15–
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