SSM2135_03 [ADI]
Dual Single-Supply Audio Operational Amplifier; 双路单电源音频运算放大器
| 型号： | SSM2135_03 |
| 厂家： | 
ADI |
| 描述： | Dual Single-Supply Audio Operational Amplifier |
| 文件： | 总16页 (文件大小：469K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Dual Single-Supply
Audio Operational Amplifier
SSM2135*
FEATURES
PIN CONNECTIONS
Excellent Sonic Characteristics
High Output Drive Capability
5.2 nV/÷Hz Equivalent Input Noise @ 1 kHz
0.001% THD+N (VO = 2.5 V p-p @ 1 kHz)
3.5 MHz Gain Bandwidth
Unity-Gain Stable
8-Lead Narrow-Body SOIC
(S Suffix)
V+
OUT A
–IN A
OUT B
–IN B
+IN B
SSM-2135
+IN A
Low Cost
V–/GND
APPLICATIONS
Multimedia Audio Systems
Microphone Preamplifier
Headphone Driver
Differential Line Receiver
Balanced Line Driver
Audio ADC Input Buffer
Audio DAC l-V Converter and Filter
Pseudo-Ground Generator
GENERAL DESCRIPTION
Particularly well suited for computer audio systems and portable
digital audio units, the SSM2135 can perform preamplification,
headphone and speaker driving, and balanced line driving and
receiving. Additionally, the device is ideal for input signal condi-
tioning in single-supply, sigma-delta, analog-to-digital converter
subsystems such as the AD1878/AD1879.
The SSM2135 Dual Audio Operational Amplifier permits excel-
lent performance in portable or low power audio systems, with
an operating supply range of +4 V to +36 V or ±2 V to ±18 V.
The unity gain stable device has very low voltage noise of
4.7 nV/÷Hz, and total harmonic distortion plus noise below 0.01%
over normal signal levels and loads. Such characteristics are
enhanced by wide output swing and load drive capability. A unique
output stage* permits output swing approaching the rail under
moderate load conditions. Under severe loading, the SSM2135
still maintains a wide output swing with ultralow distortion.
The SSM2135 is available in an 8-lead plastic SOIC package
and is guaranteed for operation over the extended industrial
temperature range of –40∞C to +85∞C.
FUNCTIONAL BLOCK DIAGRAM
V+
OUT
+IN
9V 9V
–IN
V–/GND
*Protected by U.S. Patent No. 5,146,181.
REV. E
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, norforanyinfringementsofpatentsorotherrightsofthirdpartiesthat
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
www.analog.com
© 2003 Analog Devices, Inc. All rights reserved.
(VS = 5 V, –40؇C < TA < +85؇C, unless otherwise noted.
SSM2135–SPECIFICATIONS Typical specifications apply at TA = +25؇C.)
Parameter
Symbol
Conditions
Min Typ Max
Unit
AUDIO PERFORMANCE
Voltage Noise Density
Current Noise Density
Signal-To-Noise Ratio
Headroom
en
in
f = 1 kHz
f = 1 kHz
5.2
0.5
121
5.3
nV/÷Hz
pA/÷Hz
dBu
SNR
HR
THD+N
20 Hz to 20 kHz, 0 dBu = 0.775 V rms
Clip Point = 1% THD+N, f = 1 kHz, RL = 10 kW
AV = +1, VO = 1 V p-p, f = 1 kHz, 80 kHz LPF
RL = 10 kW
dBu
Total Harmonic Distortion
0.003
0.005
%
%
RL = 32 W
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
Settling Time
SR
GBW
tS
RL = 2 kW, TA = 25∞C
0.6
0
0.9
3.5
5.8
V/ms
MHz
ms
To 0.1%, 2 V Step
INPUT CHARACTERISTICS
Input Voltage Range
Input Offset Voltage
Input Bias Current
Input Offset Current
VCM
VOS
IB
4.0
2.0
750
50
V
mV
nA
VOUT = 2 V
VCM = 0 V, VOUT = 2 V
VCM = 0 V, VOUT = 2 V
0.2
300
IOS
nA
Differential Input Impedance
Common-Mode Rejection
Large Signal Voltage Gain
ZIN
CMR
AVO
4
112
MW
0 V £ VCM £ 4 V, f = dc
0.01 V £ VOUT £ 3.9 V, RL = 600 W
87
2
dB
V/mV
OUTPUT CHARACTERISTICS
Output Voltage Swing High
VOH
VOL
ISC
RL = 100 kW
RL = 600 W
RL = 100 kW
RL = 600 W
4.1
3.9
V
V
mV
mV
mA
Output Voltage Swing Low
3.5
3.0
Short Circuit Current Limit
±30
POWER SUPPLY
Supply Voltage Range
VS
Single Supply
Dual Supply
VS = 4 V to 6 V, f = dc
VOUT = 2.0 V, No Load
VS = 5 V
4
±2
90
36
±18
V
V
dB
Power Supply Rejection Ratio
Supply Current
PSRR
ISY
120
2.8
3.7
6.0
7.6
mA
mA
VS = ±18 V, VOUT = 0 V, No Load
Specifications subject to change without notice.
–2–
REV. E
SSM2135
THERMAL CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
Thermal Resistance*
Single Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V
Dual Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±VS
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 10 V
Output Short Circuit Duration . . . . . . . . . . . . . . . . . Indefinite
Storage Temperature Range . . . . . . . . . . . . . –65∞C to +150∞C
Operating Temperature Range . . . . . . . . . . . . –40∞C to +85∞C
Junction Temperature Range (TJ) . . . . . . . . . –65∞C to +150∞C
Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . 300∞C
8-Lead SOIC
qJA
qJC
158∞C/W
43∞C/W
*qJA is specified for worst case conditions, i.e., qJA is specified for device sol-
dered in circuit board for SOIC package.
ORDERING GUIDE
Temperature
Range
Package
Description
Package
Option
Model
ESD RATINGS
883 (Human Body) Model . . . . . . . . . . . . . . . . . . . . . . . . 1 kV
EIAJ Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 V
SSM2135S –40∞C to +85∞C 8-Lead SOIC
SOIC-8
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
SSM2135 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.
REV. E
–3–
SSM2135–Typical Performance Characteristics
10
1
V
A
= 5V
S
= +1, F = 1kHz
= 1V p-p
= 10k⍀
V
V
IN
R
L
5V
WITH 80kHz FILTER
500F
0.1
R
L
0.01
2.5Vdc
0.001
10
100
1k
10k
LOAD RESISTANCE – ⍀
Test Circuit 1. Test Circuit for TPCs 1, 2, and 3
TPC 3. THD+N vs. Load (See Test Circuit)
AUDIO PRECISION
1
THD+N(%) VS. AMPL(V p-p)
1
V
= 5V
S
R
= 100k⍀
L
V
= 2.5V p-p
OUT
NONINVERTING
f = 1kHz
WITH 80kHz FILTER
0.1
R
= 32⍀
L
0.1
R
= 10k⍀
0.010
INVERTING
L
0.01
0.001
0.001
0.0005
0
10
20
30
GAIN – dB
40
50
60
50m
0.1
1
5
TPC 1. THD+N vs. Amplitude (See Test Circuit 1; AV = +1,
VS = 5 V, f = 1 kHz, with 80 kHz Low-Pass Filter)
TPC 4. THD+N vs. Gain
AUDIO PRECISION
1
THD+N(%) VS. FREQ(Hz)
1
V
= 5V
S
A
= +1, f = 1kHz
= 1V p-p
V
V
IN
R
= 10k⍀
L
WITH 80kHz FILTER
0.1
0.010
0.001
0.1
R
= 32⍀
L
0.01
R
= 10k⍀
L
0.001
0.0005
20
5
10
15
20
25
30
100
1k
10k 20k
SUPPLY VOLTAGE – V
TPC 5. THD+N vs. Supply Voltage
TPC 2. THD+N vs. Frequency (See Test Circuit 1;
AV = +1, VIN = 1 V p-p, with 80 kHz Low-Pass Filter)
–4–
REV. E
SSM2135
AUDIO PRECISION
10
SMPTE(%) VS AMPL(V p-p)
5
4
V
T
= 5V
= 25؇C
S
A
1
3
2
0.1
0.010
0.001
1
0
1
10
100
FREQUENCY – Hz
1k
50m
0.1
1
5
TPC 6. SMPTE Intermodulation Distortion (AV = +1,
VS = 5 V, f = 1 kHz, RL = 10 kW)
TPC 9. Current Noise Density vs. Frequency
AUDIO PRECISION
2.0000
AMPL(dBu) VS FREQ(Hz)
1.5000
1.0000
0.5000
0.0
1S
100
90
–0.500
–1.000
–1.500
10
0%
–2.000
20
100
1k
10k
100k
TPC 7. Input Voltage Noise (20 nV/div)
TPC 10. Frequency Response (AV = +1, VS = 5 V,
VIN = 1 V p-p, RL = 10 kW)
30
V
T
= 5V
= 25؇C
S
A
25
20
15
10
5
5µs
5µs
100
90
10
0%
20mV
20mV
0
1
10
100
FREQUENCY – Hz
1k
TPC 8. Voltage Noise Density vs. Frequency
TPC 11. Square Wave Response (VS = 5 V, AV = +1,
RL = •)
REV. E
–5–
SSM2135
50
40
30
60
V
T
= 5V
= 25؇C
S
A
V
T
= 5V
= 25؇C
S
A
40
20
AV = +100
AV = +10
AV = +1
0
–20
–40
–60
–80
–100
–120
20
10
0
105
–10
–20
10
100
1k
10k
100k
1M
10M
1k
10k
100k
1M
10M
FREQUENCY – Hz
FREQUENCY - Hz
TPC 12. Crosstalk vs. Frequency (RL = 10 kW)
TPC 15. Closed-Loop Gain vs. Frequency
100
80
140
V
T
= 5V
= 25؇C
V
T
= 5V
= 25؇C
S
S
A
A
120
100
80
0
60
45
90
135
GAIN
40
PHASE
60
20
40
0
180
225
20
0
–20
1k
10k
100k
FREQUENCY – Hz
1M
10M
100
1k
10k
100k
1M
FREQUENCY – Hz
TPC 13. Common-Mode Rejection vs. Frequency
TPC 16. Open-Loop Gain and Phase vs. Frequency
50
140
V
= 5V
= +1
= 25؇C
S
V
R
= 5V
= 2k⍀
= 100mV p-p
= 25؇C
= +1
S
45
40
35
30
25
20
15
10
5
120
100
80
A
V
A
L
T
V
IN
A
T
A
V
NEGATIVE
EDGE
+PSRR
60
–PSRR
40
POSITIVE
EDGE
20
0
–20
0
10
100
1k
10k
100k
1M
0
100
200
300
400
500
FREQUENCY – Hz
LOAD CAPACITANCE –pF
TPC 14. Power Supply Rejection vs. Frequency
TPC 17. Small Signal Overshoot vs. Load Capacitance
–6–
REV. E
SSM2135
50
45
40
35
V
A
R
= 5V
= +1
= 10k⍀
V
T
= 5V
= 25؇C
S
S
V
A
L
40
35
30
25
20
15
10
5
f = 1kHz
30
25
20
15
10
THD+N = 1%
AVCL = +100
T
= 25؇C
A
AVCL = +10
5
0
AVCL = +1
0
10
100
1k
10k
100k
1M
0
5
10
15
20
25
30
35
40
FREQUENCY – Hz
SUPPLY VOLTAGE – V
TPC 18. Output Impedance vs. Frequency
TPC 21. Output Swing vs. Supply Voltage
5
5.0
4.5
2.0
V
T
A
= 5V
= 25؇C
= +1
V
= 5.0V
S
A
S
V
4
3
2
1
0
f = 1kHz
THD+N = 1%
1.5
1.0
+SWING
= 2k⍀
R
L
4.0
+SWING
= 600⍀
+SWING
L
R
L
R
= 2k⍀
3.5
3.0
0.5
0
+SWING
= 600⍀
R
L
1
10
100
1k
10k
100k
–75
–50
–25
0
25
50
75
100
125
LOAD RESISTANCE – ⍀
TEMPERATURE – ؇C
TPC 19. Maximum Output Voltage vs. Load Resistance
TPC 22. Output Swing vs. Temperature and Load
6
2.0
V
= 5V
S
V
0.5V
= 5V
S
R
= 2k⍀
= 25؇C
= +1
L
V
4.0V
OUT
5
4
3
2
T
A
A
V
1.5
1.0
+SLEW RATE
–SLEW RATE
0.5
0
1
0
1k
10k
100k
1M
10M
–75
–50
–25
0
25
50
75
100
125
FREQUENCY – Hz
TEMPERATURE – ؇C
TPC 20. Maximum Output Swing vs. Frequency
TPC 23. Slew Rate vs. Temperature
REV. E
–7–
SSM2135
5
4
3
2
1
0
20
V
= 5.0V
= 3.9V
S
18
T
O
16
14
12
10
8
R
= 2k⍀
L
V
= ؎18V
S
V = ؎15V
S
R
= 600⍀
L
V
= +5.0V
S
6
4
2
0
–75
–75
–50
–25
0
25
50
75
100
125
–50
–25
0
25
50
75
100
125
TEMPERATURE – ؇C
TEMPERATURE – ؇C
TPC 26. Supply Current vs. Temperature
TPC 24. Open-Loop Gain vs. Temperature
500
400
300
200
100
0
70
65
5
4
V
= 5V
S
V
= +5.0V
S
GBW
60
3
V
= ؎15V
S
m
55
50
2
1
–75
–50
–25
0
25
50
75
100
125
–75
–50
–25
0
25
50
75
100
125
TEMPERATURE – ؇C
TEMPERATURE – ؇C
TPC 27. Input Bias Current vs. Temperature
TPC 25. Gain Bandwidth Product and Phase Margin
vs. Temperature
The SSM2135 is fully protected from phase reversal for inputs
going to the negative supply rail. However, internal ESD protec-
tion diodes will turn on when either input is forced more than
0.5 V below the negative rail. Under this condition, input cur-
rent in excess of 2 mA may cause erratic output behavior, in
which case a current limiting resistor should be included in the
offending input if phase integrity is required with excessive input
voltages. A 500 W or higher series input resistor will prevent
phase inversion even with the input pulled 1 V below the nega-
tive supply.
APPLICATION INFORMATION
The SSM2135 is a low voltage audio amplifier that has excep-
tionally low noise and excellent sonic quality even when driving
loads as small as 25 W. Designed for single supply use, the
SSM2135’s inputs common-mode and output swing to 0 V.
Thus with a supply voltage at 5 V, both the input and output
will swing from 0 V to 4 V. Because of this, signal dynamic
range can be optimized if the amplifier is biased to a 2 V reference
rather than at half the supply voltage.
The SSM2135 is unity-gain stable, even when driving into a fair
amount of capacitive load. Driving up to 500 pF does not cause
any instability in the amplifier. However, overshoot in the fre-
quency response increases slightly.
“Hot” plugging the input to a signal generally does not present a
problem for the SSM2135, assuming the signal does not have
any voltage exceeding the device’s supply voltage. If so, it is
advisable to add a series input resistor to limit the current, as
well as a Zener diode to clamp the input to a voltage no higher
than the supply.
The SSM2135 makes an excellent output amplifier for 5 V only
audio systems such as a multimedia workstation, a CD output
amplifier, or an audio mixing system. The amplifier has large
output swing even at this supply voltage because it is designed
to swing to the negative rail. In addition, it easily drives load
impedances as low as 25 W with low distortion.
–8–
REV. E
SSM2135
APPLICATION CIRCUITS
Low Noise Microphone Preamplifier
Low Noise Stereo Headphone Driver Amplifier
The SSM2135’s 4.7 nV/÷Hz input noise in conjunction with
low distortion makes it an ideal device for amplifying low level
signals such as those produced by microphones. Figure 3 illus-
trates a stereo microphone input circuit feeding a multimedia
sound codec. As shown, the gain is set at 100 (40 dB), although
it can be set to other gains depending on the microphone output
levels. Figure 4 shows the preamplifier’s harmonic distortion
performance with 1 V rms output while operating from a single
5 V supply.
Figure 1 shows the SSM2135 used in a stereo headphone driver
for multimedia applications with the AD1848, a 16-bit stereo
codec. The SSM2135 is equally well suited for the serial-bused
AD1849 stereo codec. The headphone’s impedance can be as
low as 25 W, which covers most commercially available high fidel-
ity headphones. Although the amplifier can operate at up to ±18 V
supply, it is just as efficient powered by a single 5 V. At this
voltage, the amplifier has sufficient output drive to deliver
distortion-free sound to a low impedance headphone.
The SSM2135 is biased to 2.25 V by the VREF pin of the AD1848
codec. The same voltage is buffered by the 2N4124 transistor to
provide “phantom power” to the microphone. A typical electret
condenser microphone with an impedance range of 100 W to 1 kW
works well with the circuit. This power booster circuit may be
omitted for dynamic microphone elements.
10k⍀
8.66k⍀
40
L
OUT
2
3
35/36
470F
+5V
0.1F
V
1
1/2
SSM2135
CC
34/37
32
GND
10F
L CH.
R CH.
V
REF
10k⍀
0.1F
10F
8
4
0.1F
+5V
8
10F
5
6
AGND
7
1/2
SSM2135
100⍀
AD1848
L CHANNEL
MIC IN
2
3
470F
1
1/2
29
10F
LMIC
35/36
+5V
V
SSM2135
CC
41
4
10k⍀
+5V
R
2k⍀
OUT
0.1F
10k⍀
8.66k⍀
34/37
32
GND
2N4124
Figure 1. A Stereo Headphone Driver for Multimedia
Sound Codec
V
REF
10F
0.1F
10k⍀
10F
R CHANNEL
MIC IN
AD1848
2k⍀
Figure 2 shows the total harmonic distortion characteristics
versus frequency driving into a 32 W load, which is a very
typical impedance for a high quality stereo headphone. The
SSM2135 has excellent power supply rejection, and as a result,
is tolerant of poorly regulated supplies. However, for best sonic
quality, the power supply should be well regulated and heavily
bypassed to minimize supply modulation under heavy loads. A
minimum of 10 mF bypass is recommended.
5
6
28
7
1/2
RMIC
SSM2135
100⍀
10k⍀
Figure 3. Low Noise Microphone Preamp for Multimedia
Sound Codec
AUDIO PRECISION
1
THD+(%) VS FREQ(Hz)
AUDIO PRECISION
1
THD+(%) VS FREQ(Hz)
0.1
0.010
0.001
0.1
0.010
20
0.0005
20
100
1k
10k 20k
100
1k
10k 20k
Figure 4. MIC Preamp THD+N Performance (VS = 5 V,
AV = 40 dB, VOUT = 1 V rms, with 80 kHz Low-Pass Filter)
Figure 2. Headphone Driver THD+N vs. Frequency into a
32 W Load (VS = 5 V, with 80 kHz Low-Pass Filter)
REV. E
–9–
SSM2135
5V SUPPLY
AD1868
VBL
18-BIT
DAC
V
L
220F
LEFT
CHANNEL
OUTPUT
1/2
DL
LL
SSM2135
9.76k⍀
7.68k⍀
18-BIT
SERIAL
REG.
47k⍀
VOL
AGND
VOR
V
330pF
REF
100pF
CK
7.68k⍀
DR
LR
V
REF
18-BIT
SERIAL
REG.
7.68k⍀
100pF
DGND
VBR
9.76k⍀
7.68k⍀
220F
RIGHT
CHANNEL
OUTPUT
1/2
SSM2135
18-BIT
DAC
V
S
330pF
47k⍀
Figure 5. 5 V Stereo 18-Bit DAC
18-Bit Stereo CD-DAC Output Amplifier
Single-Supply Differential Line Receiver
The SSM2135 makes an ideal single-supply stereo output
amplifier for audio D/A converters because of its low noise and
distortion. Figure 5 shows the implementation of an 18-bit
stereo DAC channel. The output amplifier also provides low-pass
filtering for smoothing the oversampled audio signal. The filter’s
cutoff frequency is set at 22.5 kHz and has a maximally flat
response from dc to 20 kHz.
Receiving a differential signal with minimum distortion is achieved
using the circuit in Figure 7. Unlike a difference amplifier (a
subtractor), the circuit has a true balanced input impedance
regardless of input drive levels. That is, each input always pre-
sents a 20 kW impedance to the source. For best common-mode
rejection performance, all resistors around the differential amplifier
must be very well matched. Best results can be achieved using a
10 kW precision resistor network.
As mentioned above, the amplifier’s outputs can drive directly
into a stereo headphone that has impedance as low as 25 W with
no additional buffering required.
10k⍀
+5V
10F+0.1F
Single Supply Differential Line Driver
Signal distribution and routing is often required in audio systems,
particularly portable digital audio equipment for professional
applications. Figure 6 shows a single supply line driver circuit
that has differential output. The bottom amplifier provides a 2 V
dc bias for the differential amplifier in order to maximize the
output swing range. The amplifier can output a maximum of
0.8 V rms signal with a 5 V supply. It is capable of driving into
600 W line termination at a reduced output amplitude.
20k⍀
1/2
SSM2135
20k⍀
DIFFERENTIAL
AUDIO IN
20k⍀
10F
10⍀
1/2
SSM2135
2.0V
AUDIO
OUT
+5V
1F
7.5k⍀
+5V
100⍀
1/2
SSM2135
1k⍀
5k⍀
+5V
10F+0.1F
0.1F
2.5k⍀
1/2
SSM2135
100F
AUDIO IN
Figure 7. Single-Supply Balanced Differential
Line Receiver
DIFFERENTIAL
AUDIO OUT
1k⍀
Pseudo-Reference Voltage Generator
1k⍀
For single-supply circuits, a reference voltage source is often
10k⍀
1/2
SSM2135
required for biasing purposes or signal offsetting purposes. The
circuit in Figure 8 provides a supply splitter function with low
output impedance. The 1 mF output capacitor serves as a charge
reservoir to handle a sudden surge in demand by the load as
well as providing a low ac impedance to it. The 0.1 mF feedback
capacitor compensates the amplifier in the presence of a heavy
capacitive load, maintaining stability.
2.0V
2.5k⍀
+5V
0.1F
100⍀
+5V
1/2
SSM2135
7.5k⍀
1F
5k⍀
The output can source or sink up to 12 mA of current with a
5 V supply, limited only by the 100 W output resistor. Reducing
the resistance will increase the output current capability.
Alternatively, increasing the supply voltage to 12 V also
improves the output drive to more than 25 mA.
Figure 6. Single-Supply Differential Line Driver
–10–
REV. E
SSM2135
V + = 5V Æ 12V
Logarithmic Volume Control Circuit
S
Figure 10 shows a logarithmic version of the volume control
function. Similar biasing is used. With an 8-bit bus, the AD7111
provides an 88.5 dB attenuation range. Each bit resolves a
0.375 dB attenuation. Refer to the AD7111 data sheet for attenua-
tion levels for each input code.
R3
2.5k⍀
C1
0.1F
R1
5k⍀
R4
100k⍀
+5V
0.1F
1/2
V +
S
2
OUTPUT
SSM2135
C2
1F
+5V
R2
5k⍀
10F+0.1F
3
14
47F
DGND
V
FB
OUTA
DD
1
2
L AUDIO
IN
V
IN
1/2
SSM2135
L AUDIO
OUT
AD7111
Figure 8. Pseudo-Reference Generator
Digital Volume Control Circuit
47F
AGND
10
Working in conjunction with the AD7528/PM7528 dual 8-bit
D/A converter, the SSM2135 makes an efficient audio attenuator,
as shown in Figure 9. The circuit works off a single 5 V supply.
The DACs are biased to a 2 V reference level, which is sufficient
to keep the DACs’ internal R-2R ladder switches operating prop-
erly. This voltage is also the optimal midpoint of the SSM2135’s
common-mode and output swing range. With the circuit as
shown, the maximum input and output swing is 1.25 V rms.
Total harmonic distortion measures a respectable 0.01% at 1 kHz
and 0.1% at 20 kHz. The frequency response at any attenuation
level is flat to 20 kHz.
+5V
0.1F
3
14
V
47F
DGND
FB
OUTA
DD
1
2
R AUDIO
IN
V
IN
1/2
R AUDIO
OUT
AD7111
SSM2135
47F
AGND
2k
10
DATA IN
AND
CONTROL
10
+5V
+5V
0.1F
100⍀
7.5k
2.0V
1/2
SSM2135
2.0V
Each DAC can be controlled independently via the 8-bit parallel
data bus. The attenuation level is linearly controlled by the
binary weighting of the digital data input. Total attenuation
ranges from 0 dB to 48 dB.
1F
5k
Figure 10. Single-Supply Logarithmic Volume Control
3
AD7528/PM7528
+5V
10F+0.1F
FB
OUTA
2
L AUDIO
IN
REFA
DAC A
1/2
SSM2135
L AUDIO
OUT
47F
DATA IN
6
DACA/
DACB
CONTROL
SIGNAL
15
16
CS
19
WR
FB
OUTB
20
1
18
R AUDIO
IN
REFB
DACB
1/2
SSM2135
R AUDIO
OUT
47F
2k⍀
V
DGND
5
DD
+5V
+5V
17
0.1F
100⍀
7.5k⍀
1/2
SSM2135
0.1F
2.0V
2.0V
+5V
1F
5k⍀
Figure 9. Digital Volume Control
REV. E
–11–
SSM2135
*
SPICE MACROMODEL
* CMRR STAGE & POLE AT 6 kHZ
*
*
SSM2135 SPICE Macro-Model
9/92, Rev. A
JCB/ADI
ECM
CCM
RCM1 50
50
50
4
POLY(2)
26.5E–12
1E6
3
60
2
60
0
1.6 1.6
51
51
4
*Copyright 1993 by Analog Devices, Inc.
*
*Node Assignments
*
*
*
*
*
*
RCM2 51
1
*
*
Noninverting Input
Inverting Input
Positive Supply
Negative Supply
OUTPUT STAGE
R12 37 36 1E3
R13 38 36 500
C4 37
6
20E–12
Output
C5 38 39 20E–12
M1 39 36 4 4 MN L=9E–6 W=1000E–6 AD=15E–9 AS=15E–9
M2 45 36 4 4 MN L=9E–6 W=1000E–6 AD=15E–9 AS=15E–9
.SUBCKT SSM2135
*
3
2
7
4
6
5
39 47 DX
* INPUT STAGE
D6 47 45 DX
Q3 39 40 41 QPA 8
R3
R4
C1
I1
IOS
EOS 12
4
4
19
7
2
19
20
20
18
3
1.5E3
1.5E3
5.311E–12
106E–6
25E–09
POLY(1) 51
VB
R14 7 41 375
Q4 41 43 QNA 1
R17 7 43 15
7
40 DC 0.861
7
5
4
25E–06
1
Q5 43 39
Q6 46 45
6
6
15
4
QNA 20
QPA 20
Q1
Q2
CIN
D1
D2
EN
GN1
GN2
*
19
20
3
3
2
5
0
0
3
12
2
1
1
2
2
3
18
18
3E–12
DY
DY
22
PNP1
PNP1
R18 46
4
Q7 36 46
QNA 1
M3
*
6
36 4 4 MN L=9E–6 W=2000E–6 AD=30E–9 AS=30E–9
0
0
0
1
* NONLINEAR MODELS USED
25
28
1E–5
1E–5
*
.MODEL DX D (IS=1E–15)
.MODEL DY D (IS=1E–15 BV=7)
.MODEL PNP1 PNP (BF=220)
* VOLTAGE NOISE SOURCE WITH FLICKER NOISE
DN1 21
DN2 22
VN1 21
22
23
0
DEN
DEN
DC 2
DC 2
.MODEL DEN D(IS=1E–12 RS=1016 KF=3.278E–15 AF=1)
.MODEL DIN D(IS=1E–12 RS=100019 KF=4.173E–15 AF=1)
.MODEL QNA NPN(IS=1.19E–16 BF=253 VAF=193 VAR=15 RB=2.0E3
+ IRB=7.73E–6 RBM=132.8 RE=4 RC=209 CJE=2.1E–13 VJE=0.573
+ MJE =0.364 CJC=1.64E–13 VJC=0.534 MJC=0.5 CJS=1.37E–12
+ VJS=0.59 MJS=0.5 TF=0.43E–9 PTF=30)
.MODEL QPA PNP(IS=5.21E–17 BF=131 VAF=62 VAR=15 RB=1.52E3
+ IRB=1.67E 5–RBM=368.5 RE=6.31 RC=354.4 CJE=1.1E–13
+ VJE=0.745 MJE=0.33 CJC=2.37E–13 VJC=0.762 MJC=0.4
+ CJS=7.11E–13 VJS=0.45 MJS=0.412 TF=1.0E–9 PTF=30)
.MODEL MN NMOS(LEVEL=3 VTO=1.3 RS=0.3 RD=0.3 TOX=8.5E–8
+ LD=1.48E–6WD=1E–6 NSUB=1.53E16UO=650 DELTA= 10VMAX=2E5
+ XJ=1.75E–6 KAPPA=0.8 ETA=0.066 THETA=0.01TPG=1 CJ=2.9E–4
+ PB=0.837 MJ=0.407 CJSW=0.5E–9 MJSW=0.33)
*
VN2
*
0
23
* CURRENT NOISE SOURCE WITH FLICKER NOISE
DN3 24
DN4 25
VN3 24
25
26
0
DIN
DIN
DC 2
DC 2
VN4
*
0
26
* SECOND CURRENT NOISE SOURCE
DN5 27
DN6 28
VN5 27
28
29
0
DIN
DIN
DC 2
DC 2
VN6
*
0
29
.ENDS SSM-2135
* GAIN STAGE & DOMINANT POLE AT .2000E+01 HZ
G2
R7
V3
D4
VB2 34
*
34
34
35
36
36
36
4
35
4
19
39E+06
DC
DX
1.6
20 2.65E–04
6
* SUPPLY/2 GENERATOR
ISY
R10
R11
C3
7
7
60
60
4
60
4
0.2E–3
40E+3
40E+3
1E–9
0
–12–
REV. E
SSM2135
OUTLINE DIMENSIONS
8-Lead Standard Small Outline Package [SOIC]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
5.00 (0.1968)
4.80 (0.1890)
8
1
5
4
6.20 (0.2440)
5.80 (0.2284)
4.00 (0.1574)
3.80 (0.1497)
0.50 (0.0196)
0.25 (0.0099)
1.27 (0.0500)
BSC
؋
45؇ 1.75 (0.0688)
1.35 (0.0532)
0.25 (0.0098)
0.10 (0.0040)
8؇
0.51 (0.0201)
0.33 (0.0130)
0؇ 1.27 (0.0500)
COPLANARITY
0.10
0.25 (0.0098)
0.19 (0.0075)
SEATING
PLANE
0.41 (0.0160)
COMPLIANT TO JEDEC STANDARDS MS-012AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
REV. E
–13–
SSM2135
Revision History
Location
Page
2/03—Data Sheet changed from REV. D to REV. E.
Removed 8-Lead Plastic DIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Universal
Edits to THERMAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Edits to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
–14–
REV. E
–15–
–16–
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