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Filterless High Efficiency
Mono 1.4 W Class-D Audio Amplifier
SSM2301
FEATURES
Filterless Class-D amplifier with Σ-Δ modulation
No sync necessary when using multiple Class-D amplifiers
from Analog Devices, Inc.
1.4 W into 8 Ω at 5.0 V supply with less than 1% THD + N
85% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
Greater than 98 dB SNR (signal-to-noise ratio)
Single-supply operation from 2.5 V to 5.0 V
20 nA ultralow shutdown current
Short-circuit and thermal protection
Available in 8-lead, 3 mm × 3 mm LFCSP and MSOP packages
Pop-and-click suppression
Built-in resistors reduce board component count
Fixed and user-adjustable gain configurations
The SSM2301 operates with 85% efficiency at 1.4 W into 8 Ω
from a 5.0 V supply and has a signal-to-noise ratio (SNR) that
is greater than 98 dB. Spread-spectrum modulation is used to
provide lower EMI-radiated emissions compared with other
Class-D architectures.
The SSM2301 has a micropower shutdown mode with a maximum
shutdown current of 30 nA. Shutdown is enabled by applying
a logic low to the SD pin.
The device also includes pop-and-click suppression circuitry.
This minimizes voltage glitches at the output during turn-on
and turn-off, thus reducing audible noise on activation and
deactivation.
The fully differential input of the SSM2301 provides excellent
rejection of common-mode noise on the input. Input coupling
capacitors can be omitted if the dc input common-mode voltage
is approximately V
DD
/2.
The SSM2301 also has excellent rejection of power supply noise,
including noise caused by GSM transmission bursts and RF
rectification. PSRR is typically 63 dB at 217 Hz.
The gain can be set to 6 dB or 12 dB by utilizing the gain control
select pin connected respectively to ground or to VDD. Gain
can also be adjusted externally by inserting a resistor in series
with each input pin.
The SSM2301 is specified over the commercial temperature range
(−40°C to +85°C). It has built-in thermal shutdown and output
short-circuit protection. It is available in both an 8-lead, 3 mm ×
3 mm lead-frame chip scale package (LFCSP) and an 8-lead
MSOP package.
APPLICATIONS
Mobile phones
MP3 players
Portable gaming
Portable electronics
Educational toys
GENERAL DESCRIPTION
The SSM2301 is a fully integrated, high efficiency, Class-D audio
amplifier designed to maximize performance for mobile phone
applications. The application circuit requires a minimum of
external components and operates from a single 2.5 V to 5.0 V
supply. It is capable of delivering 1.4 W of continuous output
power with less than 1% THD + N driving an 8 Ω load from
a 5.0 V supply.
The SSM2301 features a high efficiency, low noise modulation
scheme that does not require external LC output filters. The modu-
lation provides high efficiency even at low output power.
FUNCTIONAL BLOCK DIAGRAM
10µF
0.1µF
0.01µF
1
AUDIO IN+
AUDIO IN–
0.01µF
1
VBATT
2.5V TO 5.0V
VDD
OUT+
GAIN
CONTROL
MODULATOR
FET
DRIVER
OUT–
SSM2301
IN+
IN–
GAIN
SD
BIAS
SHUTDOWN
OSCILLATOR
GND
POP/CLICK
SUPPRESSION
NOTES
1
INPUT CAPS ARE OPTIONAL IF INPUT DC COMMON-MODE
VOLTAGE IS APPROXIMATELY V
DD
/2.
Figure 1.
Rev. A
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 that may result from its use. Specifications subject to change without notice. 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 owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
06163-001
SSM2301
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
Thermal Resistance ...................................................................... 4
ESD Caution.................................................................................. 4
Pin Configurations and Function Descriptions ........................... 5
Typical Performance Characteristics ............................................. 6
Typical Application Circuits ......................................................... 10
Applications Information .............................................................. 12
Overview ..................................................................................... 12
Gain Selection............................................................................. 12
Pop-and-Click Suppression ...................................................... 12
Layout .......................................................................................... 12
Input Capacitor Selection.......................................................... 12
Proper Power Supply Decoupling ............................................ 13
Outline Dimensions ....................................................................... 14
Ordering Guide .......................................................................... 14
REVISION HISTORY
10/07—Rev. 0 to Rev. A
Added MSOP Package .......................................................Universal
Changes to Features.......................................................................... 1
Changes to General Description .................................................... 1
Changes to Table 1............................................................................ 3
Deleted Evaluation Board Information Section ......................... 14
Updated Outline Dimensions ....................................................... 14
Changes to Ordering Guide .......................................................... 14
1/07—Revision 0: Initial Version
Rev. A | Page 2 of 16
SSM2301
SPECIFICATIONS
V
DD
= 5.0 V, T
A
= 25
o
C, R
L
= 8 Ω + 33 μH, unless otherwise noted.
Table 1.
Parameter
DEVICE CHARACTERISTICS
Output Power
Symbol
P
O
Conditions
V
DD
= 5.0 V, R
L
= 8 Ω, THD = 1%
f = 1 kHz, 20 kHz BW
V
DD
= 5.0 V, R
L
= 8 Ω, THD = 10%
f = 1 kHz, 20 kHz BW
V
DD
= 3.6 V, R
L
= 8 Ω, THD = 1%
f = 1 kHz, 20 kHz BW
V
DD
= 3.6 V, R
L
= 8 Ω, THD = 10%
f = 1 kHz, 20 kHz BW
V
DD
= 2.5 V, R
L
= 8 Ω, THD = 1%
f = 1 kHz, 20 kHz BW
V
DD
= 2.5 V, R
L
= 8 Ω, THD = 10%
f = 1 kHz, 20 kHz BW
P
OUT
= 1.4 W, 8 Ω, V
DD
= 5.0 V
P
O
= 1 W into 8 Ω, f = 1 kHz, V
DD
= 5.0 V
P
O
= 0.5 W into 8 Ω, f = 1 kHz, V
DD
= 3.6 V
1.0
V
CM
= 2.5 V ± 100 mV at 217 Hz
G = 6 dB; G = 12 dB
Guaranteed from PSRR test
V
DD
= 2.5 V to 5.0 V, dc input floating/ground
V
RIPPLE
= 100 mV at 217 Hz, inputs are ac grounded,
C
IN
= 0.01 μF, input referred
V
IN
= 0 V, no load, V
DD
= 5.0 V
V
IN
= 0 V, no load, V
DD
= 3.6 V
V
IN
= 0 V, no load, V
DD
= 2.5 V
SD = GND
GAIN pin = 0 V
GAIN pin = V
DD
SD = V
DD
, SD = GND
2.5
70
55
1.8
2.0
5.0
85
63
4.2
3.5
2.9
20
6
12
150
210
1.2
0.5
30
5
>100
35
98
Min
Typ
1.22
1.52
590
775
275
345
85
0.1
0.04
V
DD
− 1.0
Max
Unit
W
W
mW
mW
mW
mW
%
%
%
V
dB
MHz
mV
V
dB
dB
mA
mA
mA
nA
dB
dB
kΩ
kΩ
V
V
ms
μs
kΩ
μV
dB
Efficiency
Total Harmonic Distortion + Noise
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
Average Switching Frequency
Differential Output Offset Voltage
POWER SUPPLY
Supply Voltage Range
Power Supply Rejection Ratio
η
THD + N
V
CM
CMRR
GSM
f
SW
V
OOS
V
DD
PSRR
PSRR
GSM
I
SY
Supply Current
Shutdown Current
GAIN CONTROL
Closed-Loop Gain
Differential Input Impedance
SHUTDOWN CONTROL
Input Voltage High
Input Voltage Low
Turn-On Time
Turn-Off Time
Output Impedance
NOISE PERFORMANCE
Output Voltage Noise
Signal-to-Noise Ratio
I
SD
A
V
0
A
V
1
Z
IN
V
IH
V
IL
t
WU
t
SD
Z
OUT
e
n
SNR
I
SY
≥ 1 mA
I
SY
≤ 300 nA
SD rising edge from GND to V
DD
SD falling edge from V
DD
to GND
SD = GND
V
DD
= 2.5 V to 5.0 V, f = 20 Hz to 20 kHz, inputs are
ac grounded, sine wave, A
V
= 6 dB, A weighting
P
OUT
= 1.4 W, R
L
= 8 Ω
Rev. A | Page 3 of 16
SSM2301
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings apply at 25°C, unless otherwise noted.
Table 2.
Parameter
Supply Voltage
Input Voltage
Common-Mode Input Voltage
Storage Temperature Range
Operating Temperature Range
Junction Temperature Range
Lead Temperature (Soldering, 60 sec)
Rating
6V
V
DD
V
DD
−65°C to +150°C
−40°C to +85°C
−65°C to +165°C
300°C
THERMAL RESISTANCE
θ
JA
is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3. Thermal Resistance
Package Type
8-lead, 3 mm × 3 mm LFCSP
8-lead MSOP
θ
JA
62
210
θ
JC
20.8
45
Unit
°C/W
°C/W
ESD CAUTION
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Rev. A | Page 4 of 16
