Page 1
Mono 1.5 W/Stereo 250 mW
RIGHT IN
RIGHT OUT
56
GND
BYPASS
47
LEFT IN
SHUTDOWN
LEFT OUT/BTL–
V
DD
1
2
3
10
9
8 BTL+
SSM2250
SE/BTL
LEFT IN
LEFT SE/
MONO BTL
OUT–
MONO BTL
OUT+
RIGHT
SE OUT
V
DD
RIGHT IN
BYPASS
CAP
V
DD
CLICK AND POP
REDUCTION
BIAS
V
DD
GND
SHUTDOWN
SWITCHING
CIRCUITRY
BTL/SE
SELECT
A1
A2
A3
NC
LEFT IN
SHUTDOWN
1GND
RIGHT IN
NC
LEFT OUT/BTL
V
DD
BTL1
NC
RIGHT OUT
NC
BYPASS
114
78
SSM2250
NC = NO CONNECT
SE/BTL
a
FEATURES
Part of SoundMax
Mono 1.5 W Differential or Stereo 250 mW Output
Single-Supply Operation: 2.7 V to 6 V
Low Shutdown Current = 60 A
PC 99 Compliant
Low Distortion: 0.2% THD at 1.5 W
Wide Bandwidth: 4 MHz
Unity-Gain Stable
APPLICATIONS
Desktop, Portable or Palmtop Computers
Sound Cards
Communication Headsets
2-Way Communications
Handheld Games
GENERAL DESCRIPTION
The SSM2250 is intended for use in desktop computers that have
basic audio functions. It is also ideal for any audio system that needs
to provide both an internal monaural speaker and a stereo line or
headphone output. Combined with an AC’97 Codec it provides a
PC audio system that meets the PC 99 requirements. The SSM2250
is compact and requires a minimum of external components.
The SSM2250 features an audio amplifier capable of delivering
1.5 W of low distortion power into a mono 4 Ω bridged-tied load
(BTL) or 2 ⫻ 90 mW into stereo 32 Ω single-ended load (SE)
headphones. Both amplifiers provide rail-to-rail outputs for maximum dynamic range from a single supply. The balanced output
provides maximum output from 5 V supply and eliminates the
need for a coupling capacitor.
The SSM2250 can automatically switch between an internal
mono speaker and external headphones. The device can run from
a single supply, ranging from 2.7 V to 6 V, with an active supply
current of 9␣ mA typical. The ability to shut down the amplifiers,
(60 µA shutdown current) makes the SSM2250 an ideal speaker
amplifier for battery-powered applications.
The SSM2250 is specified over the industrial (–40°C to +85°C)
temperature range. It is available in 14-lead TSSOP and 10-lead
MSOP surface mount packages.
®
Audio Solution for Desktop Computers
Power Amplifier
SSM2250
PIN CONFIGURATIONS
10-Lead MSOP
(RM Suffix)
14-Lead TSSOP
(RU Suffix)
SoundMax is a registered trademark of Analog Devices, Inc.
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.
Figure 1. Functional Block Diagram
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1999
Page 2
SSM2250–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
(VS = 5.0 V, VCM = 2.5 V, TA = 25ⴗC unless otherwise noted)
Parameter Symbol Conditions Min Typ Max Unit
DEVICE CHARACTERISTICS␣
Output Offset Voltage V
Large Signal Voltage Gain A
Output Power P
Output Impedance Z
OS
VO
OUT
OUT
BTL Mode; AV = 2; BTL+ to BTL– 4 100 mV
R
= 2 kΩ 2 V/mV
L
SE Mode: R
BTL Mode: R
= 32 Ω, THD < 1% 90 mW
L
= 8 Ω, THD < 1% 1,000 mW
L
0.1 Ω
SHUTDOWN INPUT
Input Voltage High V
Input Voltage Low V
IH
IL
I
< 100 µA 2.0 V
S
IS > 1 mA 0.8 V
POWER SUPPLY␣
Supply Current I
S
BTL Mode 6.4 mA
SE Mode 6.4 mA
Supply Current/Amplifier I
S
60 µA
DYNAMIC PERFORMANCE␣
Slew Rate SR R
= 100 kΩ, CL = 50 pF 4 V/µs
L
Gain Bandwidth Product GBP 4 MHz
Phase Margin Φo 84 Degrees
NOISE PERFORMANCE␣
Voltage Noise Density e
Specifications subject to change without notice.
n
f = 1 kHz 45 nV/√Hz
ELECTRICAL CHARACTERISTICS
(VS = 2.7 V, VCM = 1.35 V, TA = 25ⴗC unless otherwise noted)
Parameter Symbol Conditions Min Typ Max Unit
DEVICE CHARACTERISTICS␣
Output Offset Voltage V
Large Signal Voltage Gain A
Output Power P
Output Impedance Z
OS
VO
OUT
OUT
BTL Mode; AV = 2; BTL+ to BTL– 4 100 mV
R
= 2 kΩ 2 V/mV
L
SE Mode: R
BTL Mode: R
= 32 Ω, THD < 1% 25 mW
L
= 8 Ω, THD < 1% 300 mW
L
0.1 Ω
SHUTDOWN INPUT
Input Voltage High V
Input Voltage Low V
IH
IL
I
< 100 µA 2.0 V
S
IS > 1 mA 0.8 V
POWER SUPPLY␣
Supply Current I
S
BTL Mode 6.4 mA
SE Mode 6.4 mA
Supply Current/Amplifier I
S
32 µA
DYNAMIC PERFORMANCE␣
Slew Rate SR R
= 100 kΩ, CL = 50 pF 4 V/µs
L
Gain Bandwidth Product GBP 4 MHz
Phase Margin Φo 84 Degrees
NOISE PERFORMANCE␣
Voltage Noise Density e
Specifications subject to change without notice.
n
f = 1 kHz 45 nV/√Hz
–2– REV. 0
Page 3
ABSOLUTE MAXIMUM RATINGS
WARNING!
ESD SENSITIVE DEVICE
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Differential Input Voltage
2
. . . . . . . . . . . . . . . . . . . . . . . . ±5 V
Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . ±6 V
ESD Susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000 V
Storage Temperature Range
RM, RU Packages . . . . . . . . . . . . . . . . . . –65°C to +150°C
Operating Temperature Range
SSM2250 . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
Junction Temperature Range
RM, RU Packages . . . . . . . . . . . . . . . . . . –65°C to +165°C
Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300°C
NOTES
1
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 conditions for extended periods may affect device reliability.
2
Differential Input Voltage or ± VS, whichever is lower.
1
Package Type
10-Lead MSOP (RM) 200 44 °C/W
14-Lead TSSOP (RU) 180 35 °C/W
NOTE
1
θJA is specified for worst-case conditions, i.e., θ
in circuit board for surface mount packages.
ORDERING GUIDE
Temperature Package Package
Model Range Description Option
SSM2250RM –40°C to +85°C 10-Lead MSOP RM-10
SSM2250RU –40°C to +85°C 14-Lead TSSOP RU-14
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 SSM2250 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.
SSM2250
1
JA
JC
is specified for device soldered
JA
Unit
–3–REV. 0
Page 4
SSM2250
10
VS = 5V
BTL MODE
R
= 8V
L
= 1mF
C
B
P
= 1W
OUT
AV = 2
1
TOTAL HARMONIC DISTORTION – %
0.1
20 20k100 1k 10k
FREQUENCY – Hz
Figure 2. BTL Out THD + N vs. Frequency
10
VS = 2.7V
BTL MODE
R
= 8V
L
= 1mF
C
B
P
= 0.25W
OUT
AV = 2
1
1
VS = 5V
SE MODE
R
= 32V
L
= 1mF
C
B
P
= 60mW
OUT
AV = 1
0.1
TOTAL HARMONIC DISTORTION – %
0.01
20 20k100
FREQUENCY – Hz
1k
Figure 5. SE Out THD + N vs. Frequency
1
VS = 2.7V
SE MODE
R
= 32V
L
= 1mF
C
B
P
= 15mW
OUT
AV = 1
0.1
10k
TOTAL HARMONIC DISTORTION – %
0.1
20 20k100 1k 10k
FREQUENCY – Hz
Figure 3. BTL Out THD + N vs. Frequency
10
VS = VARIES
BTL MODE
R
= 8V
L
= 1mF
C
B
VIN = 1kHz
AV = 2
1
TOTAL HARMONIC DISTORTION – %
0.1
10m 2100m
OUTPUT POWER – W
2.7V
3.3V
Figure 4. THD + N vs. Output Power
TOTAL HARMONIC DISTORTION – %
0.01
20 20k100
FREQUENCY – Hz
1k
10k
Figure 6. SE Out THD + N vs. Frequency
10
SE MODE
R
= 32V
L
C
= 1mF
B
= 1kHz
V
IN
1
0.1
5V
1
TOTAL HARMONIC DISTORTION – %
0.01
10 200100
2.7V
3.3V
OUTPUT POWER – mW
5V
Figure 7. BTL Out THD + N vs. Output Power
–4– REV. 0
Page 5
TOTAL HARMONIC DISTORTION – %
OUTPUT POWER – mW
10
1
0.01
10 200100
TOTAL HARMONIC DISTORTION – %
0.1
VS = 5V
SE MODE
R
L
= 32V
C
B
= 1mF
VIN = 20Hz
AV = 1
OUTPUT POWER – mW
10
1
0.01
10 200100
TOTAL HARMONIC DISTORTION – %
0.1
VS = 5V
SE MODE
R
L
= 8V
C
B
= 1mF
VIN = 20kHz
AV = 1
10
1
VS = 5V
BTL MODE
R
= 8V
L
= 1mF
C
B
VIN = 20Hz
AV = 2
SSM2250
0.1
10m 2100m
OUTPUT POWER – W
1
Figure 8. BTL Out THD + N vs. Output Power at 20 Hz
10
VS = 5V
BTL MODE
RL = 8V
= 1mF
C
B
VIN = 20kHz
AV = 2
1
TOTAL HARMONIC DISTORTION – %
0.1
10m 2100m
OUTPUT POWER – W
1
Figure 9. BTL Out THD + N vs. Output Power at 20 kHz
Figure 10. SE Out THD + N vs. Output Power at 20 Hz
Figure 11. SE Out THD + N vs. Output Power at 20 kHz
–5–REV. 0
Page 6
SSM2250
PRODUCT OVERVIEW
The SSM2250 is a low distortion power amplifier that can drive a
set of stereo headphones or a single 8 Ω loudspeaker. It contains
three rail-to-rail output op amps, click and pop reduction biasing,
and all necessary switching circuitry. In SE (Single-Ended) Mode,
the device automatically mutes the internal 8 Ω speaker. In BTL
(Bridge-Tied Load) Mode, the internal speaker is activated.
The SSM2250 can operate from a 2.7 V to 5.5 V single supply.
The rail-to-rail outputs can be driven to within 400 mV of either
supply rail while supplying a sustained output current of 350 mA
into 8 Ω. The device is unity-gain stable and requires no external compensation capacitors. The SSM2250 can be configured
for gains of up to 40␣ dB.
TYPICAL APPLICATION
In SE Mode, the device operates similar to a high current output,
dual op amp. A1 and A3 are independent amplifiers with a gain of
–R2/R1. The outputs of A1 and A3 are used to drive the external
headphones plugged into the headphone jack. Amplifier A2 is shut
down to a high output impedance state. This prevents current from
flowing through the 8 Ω internal speaker, thereby muting it.
Although the gains of A1 and A3 can be set independently, it is
recommended that the feedback and feedforward resistor around
both amplifiers be equal. This will prevent one channel from
becoming louder than the other.
In BTL mode, the current into the Right In pin is directed to
the input of A1. This effectively sums the Left and Right In
audio signals. The A2 amplifier is activated and configured with
a fixed gain of A
␣ =␣ –1. This produces a balanced output con-
V
figuration that drives the internal speaker. Because the BTL
output voltages swing opposite to each other, the gain to the
speaker in BTL mode is twice the gain of SE mode. The voltage
across the internal speaker can be written:
R
VVV
SPEAKER LEFT RIGHT
=+
()
×× 2
2
(1)
R
1
The bridged output configuration offers the advantage of a more
efficient power transfer from the input to the speaker. Because
both outputs are symmetric, the dc voltage bias across the 8 Ω
internal speaker is zero. This eliminates the need for a coupling
capacitor at the output. In BTL mode, the A3 amplifier is shut
down to conserve power.
R2
20kV
In BTL Mode, the SSM2250 can achieve 1␣ W continuous output
into 8␣ Ω at ambient temperatures up to 40°C. The power derating
curve shown in Figure 15 should be observed for proper operation at
higher ambient temperatures. For a standard 14-lead TSSOP package, typical junction-to-ambient temperature thermal resistance (θ
)
JA
is 180°C/W on a 2-layer board, and 140°C/W on a 4-layer board.
Internal Speaker/External Headphones Automatic Switching
Pin 4 on the SSM2250 controls the switching between BTL and
SE Modes. Logic low to Pin 4 activates BTL Mode, while logic
high activates SE Mode. The configuration shown in Figure 12
provides the appropriate logic voltages to Pin 4, muting the
internal speaker when headphones are plugged into the jack.
A stereo headphone jack with a normalizing pin is required for
the application. With no plug inserted, a mechanical spring
connects the normalizing pin to the output pin in the jack.
Once a plug is inserted, this connection is broken.
Referring to Figure 12, Pin 4 of the SSM2250 is connected to the
normalizing pin for the right channel output. This is the pin in
the headphone jack that will hit the ring on the headphone plug.
A 100 kΩ pull-up resistor to 5 V is also connected at this point.
With a headphone plug inserted, the normalizing pin disconnects
from the output pin, and Pin 4 is pulled up to 5 V, activating SE
Mode on the SSM2250. This mutes the internal speaker while
driving the stereo headphones.
Once the headphone plug is removed, the normalizing pin connects to the output pin. This drives the voltage at Pin 4 to 50 mV,
as this point is pulled low by the 1 kΩ resistor now connected to
the node. The SSM2250 goes into BTL mode, deactivating the
right SE amplifier to prevent the occurrence of any false mode
switching.
It is important to connect Pin 4 and the 100 kΩ pull up resistor
to the normalizing pin for the right output in the headphone
jack. Connecting them to the left output normalizing pin will
result in improper operation from the device. The normalizing
pin to the left output in the headphone jack should be left open.
Coupling Capacitors
Output coupling capacitors are not required to drive the internal
speaker from the BTL outputs. However, coupling capacitors are
required between the amplifier’s SE outputs and the headphone
jack to drive external headphones. This prevents dc current from
flowing through the headphone speakers, whose resistances are
typically on the order of 80 Ω.
LEFT IN
SHUTDOWN
RIGHT IN
1mF
1mF
20kV
R1
20kV
R1
1
NC
2
3
SSM2250
4
5
6
7
NC
NC = NO CONNECT
R2
20kV
14
13
12
11
10
9
8
Figure 12. Typical Application
–6– REV. 0
NC
10mF
NC
220mF
+
–
1kV
BTL
5V
OUT
+
220mF
+
5V
100kV
NC
1kV
Page 7
SSM2250
The output coupling capacitor creates a high-pass filter with a
cutoff frequency of:
f
dB
−=3
2
π
1
(2)
RC
LC
Where, RL is the resistance of the headphone, and
C
is the output coupling capacitor.
C
Although a majority of headphones have around 80 Ω of resistance,
this resistance can vary between models and manufacturers. Headphone resistances are commonly between 32 Ω to 600 Ω. Using a
220 µF capacitor as shown in Figure 12, the worst-case –3 dB corner
frequency would be 22 Hz, with a 32 Ω headphone load. Smaller
output capacitors could be used at the expense of low frequency
response to the headphones.
An input coupling capacitor should be used to remove dc bias
from the inputs to the SSM2250. Again, the input coupling
capacitor in combination with the input resistor will create a
high-pass filter with a corner frequency of:
f
dB−=3
1
211
(3)
π
RC
Using the values shown in Figure 2, where R1␣ =␣ 20 kΩ and
C1␣ =␣ 1 µF, will create a corner frequency of 8 Hz. This is
acceptable, as the PC 99 audio requirement specifies the computer audio system bandwidth to be 20 Hz to 20 kHz.
Pin 10 on the SSM2250 provides the proper bias voltage for the
amplifiers. A 0.1 µF capacitor should be connected here to
reduce sensitivity to noise on the power supply. A larger capacitor can be used should more rejection from power supply noise
be required.
The SSM2250 has excellent phase margin and is stable even
under heavy loading. Therefore, a feedback capacitor in parallel
with R2 is not required, as it is in some competitors’ products.
Power Dissipation
An important advantage in using a bridged output configuration
is the fact that bridged output amplifiers are more efficient than
single-ended amplifiers in delivering power to a load.
1.5
VDD = 5V
1.25
1.0
0.75
RL = 4V
RL = 8V
2
V
2
P
DISS MAX
,
DD
=
(4)
2
π
R
L
Using Equation 4 and the power derating curve in Figure 15,
the maximum ambient temperature can be easily found. This
ensures that the SSM2250 will not exceed its maximum junction temperature of 150°C.
The power dissipation for a single-ended output application where
an output coupling capacitor is used is shown in Figure 14.
0.35
VDD = 5V
0.3
0.25
0.2
0.15
0.1
POWER DISSIPATION – W
0.05
0
0
RL = 8V
RL = 16V
0.2 0.3
OUTPUT POWER – W
RL = 4V
0.40.1
Figure 14. Power Dissipation vs. Single-Ended Output
Power (V
␣ = 5␣ V)
DD
The maximum power dissipation for a single-ended output is:
2
V
P
DISS MAX
,
DD
=
(5)
2
R
2
π
L
Because the SSM2250 is designed to drive two single-ended
loads simultaneously, the worst-case maximum power dissipation
in SE Mode is twice the value of Equation␣ 5.
A thorough mathematical explanation behind Equation␣ 4 and
Equation␣ 5 is given in the SSM2211 data sheet, which can be
downloaded at http://www.analog.com.
Example: Given worst-case stereo headphone loads of 32 Ω,
the maximum power dissipation of the SSM2250 in SE Mode
with a 5 V supply would be:
2
V
5
P
DISS MAX,
()
2
232
πΩ
=
79
=
mW
(6)
With an 8 Ω internal speaker attached, the maximum power
dissipation in BTL mode is (from Equation 4):
0.5
POWER DISSIPATION – W
0.25
0
0
0.25
RL = 16V
0.5 0.75 1.0 1.25 1.5
OUTPUT POWER – W
Figure 13. Power Dissipation vs. Output Power in BTL Mode
2
×
V
25
P
DISS MAX,
()
2
πΩ
8
=
633
=
mW
(7)
It can be easily seen that power dissipation from BTL Mode
operation is of greater concern than SE Mode.
Solving for Maximum Ambient Temperature
To protect the SSM2250 against thermal damage, the junction
temperature of the die should not exceed 150°C. The maximum
allowable ambient temperature of the application can be easily
found by solving for the expected maximum power dissipation in
Equation␣ 4 and Equation␣ 5, and using Equation␣ 8.
–7–REV. 0
Page 8
SSM2250
Continuing from the previous example, the θ
of the SSM2250
JA
14-lead TSSOP package on a 4-layer board is 140°C/W. To ensure
the SSM2250 die junction temperature stays below 150°C, the
maximum ambient temperature can be solved using Equation 8.
T 150 C P
AMB, MAX JA DISS, MAX
=+ ° − ×θ
=+ ° − ° ×
150 140 0 633C C/W W. (8)
=+ °61 C
()
So the maximum ambient temperature must remain below 61°C
to protect the device against thermal damage.
Another method for finding the maximum allowable ambient
temperature is to use the power derating curve in Figure 15.
The y-axis corresponds to the expected maximum power dissipation, and the x-axis is the corresponding maximum ambient
temperature. Either method will return the same answer.
1.0
14-LEAD TSSOP
0.8
= 1408C/W
u
JA
10-LEAD MSOP
0.6
= 1808C/W
u
JA
0.4
POWER DISSIPATION – W
0.2
0
0
AMBIENT TEMPERATURE – 8C
50 75
T
= 1508C/W
J,MAX
FREE AIR
NO HEAT SINK
10025
Figure 15. Maximum Power Dissipation vs. Ambient
Temperature
Maximum Output Power
The maximum amount of power that can be delivered to a
speaker is a function of the supply voltage and the resistance of
the speaker. Figure 15 shows the maximum BTL output power
possible from the SSM2250. Maximum output power is defined
as the point at which the output has greater than 1% distortion.
1.6
1.4
1.2
RL = 4V
The output power in SE mode is exactly one-fourth the equivalent
output power in BTL mode. This is because twice the voltage swing
across the two BTL outputs results in 4⫻ the power delivered to the
load. Figure 17 shows the maximum output power in SE mode vs.
supply voltage for various headphone loads.
100
75
50
25
MAXIMUM OUTPUT @ THD 1% – mW
0
1.5 5.02.0 2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE – V
Figure 17. Maximum SE Output Power vs. V
RL = 32V
RL = 64V
R
= 128V
L
S
Example: An application requires only 500␣ mW to be output in
BTL Mode into an 8␣ Ω speaker. By inspection, the minimum
supply voltage required is 3.3␣ V.
Speaker Efficiency and Loudness
The effective loudness of 1 W of power delivered into an 8 Ω
speaker is a function of the efficiency of the speaker. The efficiency
of a speaker is typically rated at the sound pressure level (SPL) at
1 meter in front of the speaker with 1 W of power applied to the
speaker. Most speakers are between 85 dB and 95 dB SPL at one
meter at 1 W of power. Table I shows a comparison of the relative
loudness of different sounds.
Table I. Typical Sound Pressure Levels
Source of Sound dB SPL
Threshold of Pain 120
Heavy Street Traffic 95
Cabin of Jet Aircraft 80
Average Conversation 65
Average Home at Night 50
Quiet Recording Studio 30
Threshold of Hearing 0
1.0
0.8
0.6
0.4
MAXIMUM OUTPUT @ THD 1% – W
0.2
0
1.5 5.02.0 2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE – V
Figure 16. Maximum BTL Output Power vs. V
R
= 16V
L
RL = 8V
S
To find the minimum supply voltage needed to achieve a specified maximum undistorted output power, simply use Figure 16.
–8– REV. 0
It can be easily seen that 1␣ W of power into a speaker can produce
quite a bit of acoustic energy.
Shutdown Feature
The SSM2250 can be put into a low power consumption shutdown mode by connecting Pin␣ 3 to V
. In shutdown mode, the
DD
SSM2250 has low supply current of 60 µA.
Pin␣ 3 should be connected to ground for normal operation. Con-
necting Pin␣ 3 to V
will shut down all amplifiers and put all outputs
DD
into a high impedance state, effectively muting the SSM2250. A
pull-up or pull-down resistor is not required. Pin 3 should never be
left floating as this could produce unpredictable results.
PC 99 Compliant Computer Audio Reference Design
The schematic shown in Figure 18 is a reference design for a
complete audio system in a computer. The design is compliant
with the PC 99 standard for computer audio.
Page 9
SSM2250
The AD1881 is an AC’97 Ver. 2.1 audio codec available from
Analog Devices. The stereo output from the AD1881 is coupled
into the SSM2250, which is used to drive a mono internal
speaker and stereo headphones. The internal speaker switching
is controlled by the SSM2250 through the normalizing pin on
the headphone jack. The AD1881 controls the shutdown pin on
the SSM2250, and is activated through the power management
software drivers installed on the computer.
= 5V
AV
DD
AC CLK
SDATA
OUT
BITCLK
SDATA
IN 0
SYNC
RST#
PCBEEP
MONO
PHONE
AUX
LEFT
AUX IN
10mF
C20
27pF
0.1mF
C6
R10
10kV
C23
C7
0.1mF
C8
22pF
C11
22pF
Y1
24.576MHz
SMT
R8
47V
R12
4.7kV
R16
4.7kV
AVDD = 5V
C22
1mF
R11
1kV
C2
10mF
NC
NCNCNC NC NC NC NC
48 47 46 45 44 43 42 41 40 39 38 37
1
2
3
4
5
6
7
8
9
10
11
12
13 14 15 16 17 18 19 20 21 22 23 24
NC
NC NC
C26
1mF
C29
1mF
R14
4.7kV
C31
1mF
R17
4.7kV
NC = NO CONNECT
AD1881
C3
0.1mF
For more information on the AD1881, the data sheet
can be downloaded from the Analog Devices web site at
http://www.analog.com.
R1
AV
R2
100kV
MONO OUT
C9
36
1mF
35
34
33
32
31
30
29
28
27
26
25
C24
1mF
C27
1mF
C30
1mF
C32
1mF
C33
1mF
20kV
= 5V
DD
0.1mF
C21
SSM2250
1
NC NC
2
3
4
5
6
7
NC
R5
20kV
R6
20kV
C10
1mF
C14
1mF
AVDD = 5V
C25
1mF
C28
0.001mF
R15
4.7kV
R19
4.7kV
4.7kV
4.7kV
R7
20kV
C12
0.1mF
C15
1mF
R13
R18
14
13
12
11
10
9
8
AVDD = 5V
NC
C13
0.047mF
C16
270pF
C16
10mF
R9
2kV
C1
100mF
+
1kV
C4
10mF
+
C17
270pF
LINE IN RIGHT
LINE IN LEFT
MIC IN
CD RIGHT
CD GND
CD LEFT
TO SPEAKER2
TO SPEAKER+
R3
NC
C5
100mF
+
R4
1kV
LINE OUT RIGHT
LINE OUT LEFT
C19
0.1mF
Figure 18. PC 99 Compliant Audio System Reference Design
–9–REV. 0
Page 10
SSM2250
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
10-Lead MSOP
(RM Suffix)
0.124 (3.15)
0.112 (2.84)
0.124 (3.15)
0.112 (2.84)
0.038 (0.97)
0.030 (0.76)
0.177 (4.50)
0.169 (4.30)
10 6
1
PIN 1
0.0197 (0.50) BSC
0.122 (3.10)
0.110 (2.79)
0.006 (0.15)
0.002 (0.05)
0.201 (5.10)
0.193 (4.90)
14
1
0.199 (5.05)
0.187 (4.75)
5
0.043 (1.09)
0.037 (0.94)
0.016 (0.41)
0.006 (0.15)
SEATING
PLANE
14-Lead TSSOP
(RU Suffix)
8
0.256 (6.50)
0.246 (6.25)
7
0.011 (0.28)
0.003 (0.08)
0.120 (3.05)
0.112 (2.84)
68
08
C3729–2.5–10/99
0.022 (0.56)
0.021 (0.53)
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
PIN 1
0.0256
(0.65)
BSC
0.0118 (0.30)
0.0075 (0.19)
0.0433
(1.10)
MAX
0.0079 (0.20)
0.0035 (0.090)
88
08
0.028 (0.70)
0.020 (0.50)
–10– REV. 0
PRINTED IN U.S.A.
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