ANALOG DEVICES SSM2335 Service Manual
Filterless, High Efficiency,
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FEATURES
Filterless Class-D amplifier with Σ-Δ modulation
No sync necessary when using multiple Class-D amplifiers
from Analog Devices, Inc.
3 W into 3 Ω load and 1.4 W into 8 Ω load at 5.0 V supply
with <1% total harmonic distortion (THD + N)
93% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
>96 dB signal-to-noise ratio (SNR)
Single-supply operation from 2.5 V to 5.5 V
20 nA ultralow shutdown current
Short-circuit and thermal protection
Available in 9-ball, 1.5 mm × 1.5 mm WLCSP
Pop-and-click suppression
Built-in resistors reduce board component count
Default fixed 18 dB or user-adjustable gain setting
APPLICATIONS
Mobile phones
MP3 players
Portable gaming
Portable electronics
Educational toys
GENERAL DESCRIPTION
The SSM2335 is a fully integrated, high efficiency, Class-D audio
amplifier. It is 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 5.5 V
supply. It is capable of delivering 3 W of continuous output power
with <1% THD + N driving a 3 Ω load from a 5.0 V supply.
Mono 3 W Class-D Audio Amplifier
SSM2335
The SSM2335 features a high efficiency, low noise modulation
scheme that requires no external LC output filters. The modulation continues to provide high efficiency even at low output
power. It operates with 93% efficiency at 1.4 W into 8 Ω or 85%
efficiency at 3 W into 3 Ω from a 5.0 V supply and has an SNR
of >96 dB. Spread-spectrum pulse density modulation is used
to provide lower EMI-radiated emissions compared with other
Class-D architectures.
The SSM2335 has a micropower shutdown mode with a typical
shutdown current of 20 nA. Shutdown is enabled by applying
a logic low to the
The device also includes pop-and-click suppression circuitry.
This suppression circuitry minimizes voltage glitches at the
output during turn-on and turn-off, reducing audible noise
on activation and deactivation.
The fully differential input of the SSM2335 provides excellent
rejection of common-mode noise on the input. Input coupling
capacitors can be omitted if the input dc common-mode voltage
is approximately V
The default gain of the SSM2335 is 18 dB, but users can reduce the
gain by using a pair of external resistors (see the Gain section).
The SSM2335 is specified over the industrial temperature range
of −40°C to +85°C. It has built-in thermal shutdown and output
short-circuit protection. It is available in a 9-ball, 1.5 mm ×
1.5 mm wafer level chip scale package (WLCSP).
SD
DD
pin.
/2.
FUNCTIONAL BLOCK DIAGRAM
SSM2335
AUDIO IN+
AUDIO IN–
SHUTDOWN
*INPUT CAPACITORS ARE O PTIONAL IF INPUT DC COMMON-MO DE
VOLTAGE IS APPROXIMATELY V
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 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.
47nF*
47nF*
IN+
IN–
SD
20kΩ
20kΩ
/2.
DD
MODULATOR
BIAS
10µF
160kΩ
(Σ-Δ)
160kΩ
Figure 1.
0.1µF
VDD
FET
DRIVER
INTERNAL
OSCILLATOR
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 ©2008 Analog Devices, Inc. All rights reserved.
POP-AND-CLICK
SUPPRESSION
GND
VBATT
2.5V TO 5.5V
OUT–
OUT+
7551-001
SSM2335
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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 Configuration and Function Descriptions ............................. 5
Typical Performance Characteristics ............................................. 6
REVISION HISTORY
10/08—Revision 0: Initial Version
Typical Application Circuits ......................................................... 11
Theory of Operation ...................................................................... 12
Overview ..................................................................................... 12
Gain .............................................................................................. 12
Pop-and-Click Suppression ...................................................... 12
Output Modulation Description .............................................. 12
Layout .......................................................................................... 13
Input Capacitor Selection .......................................................... 13
Power Supply Decoupling ......................................................... 13
Outline Dimensions ....................................................................... 14
Ordering Guide .......................................................................... 14
Rev. 0 | Page 2 of 16
SSM2335
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SPECIFICATIONS
VDD = 5.0 V, TA = 25°C, RL = 8 Ω +33 μH, unless otherwise noted.
Table 1.
Parameter Symbol Test Conditions/Comments
DEVICE CHARACTERISTICS
Output Power P
O
R
R
R
R
R
R
R
R
R
R
R
f = 1 kHz, 20 kHz BW
RL = 8 Ω, THD = 1%, VDD = 5.0 V 1.48 W
= 8 Ω, THD = 1%, VDD = 3.6 V 0.75 W
L
= 8 Ω, THD = 10%, VDD = 5.0 V 1.84 W
L
= 8 Ω, THD = 10%, VDD = 3.6 V 0.94 W
L
= 4 Ω, THD = 1%, VDD = 5.0 V 2.72 W
L
= 4 Ω, THD = 1%, VDD = 3.6 V 1.38 W
L
= 4 Ω, THD = 10%, VDD = 5.0 V 3.40
L
= 4 Ω, THD = 10%, VDD = 3.6 V 1.72 W
L
= 3 Ω, THD = 1%, VDD = 5.0 V
L
= 3 Ω, THD = 1%, VDD = 3.6 V 1.72 W
L
= 3 Ω, THD = 10%, VDD = 5.0 V
L
= 3 Ω, THD = 10%, VDD = 3.6 V 2.14 W
L
Efficiency η PO = 1.4 W, 8 Ω, VDD = 5.0 V 93 %
Total Harmonic Distortion + Noise THD + N PO = 1 W into 8 Ω, f = 1 kHz, VDD = 5.0 V 0.01 %
P
= 0.5 W into 8 Ω, f = 1 kHz, VDD = 3.6 V 0.01 %
O
Input Common-Mode Voltage Range VCM 1.0 VDD − 1.0 V
Common-Mode Rejection Ratio CMRR
GSM VCM
= 2.5 V ± 100 mV at 217 Hz, output referred 60 dB
Average Switching Frequency fSW 300 kHz
Differential Output Offset Voltage V
OOS
Gain = 18 dB 2.0 mV
POWER SUPPLY
Supply Voltage Range V
DD
Guaranteed from PSRR test 2.5 5.5 V
Power Supply Rejection Ratio PSRRDC VDD = 2.5 V to 5.0 V, dc input floating 60 85 dB
PSRR
Supply Current I
SY
V
V
V
V
V
Shutdown Current ISD
V
GSM
= 100 mV at 217 Hz, inputs ac GND, CIN = 0.1 μF 65 dB
RIPPLE
VIN = 0 V, no load, VDD = 5.0 V 3.2 mA
= 0 V, no load, VDD = 3.6 V 2.8 mA
IN
= 0 V, no load, VDD = 2.5 V 2.4 mA
IN
= 0 V, load = 8 Ω + 33 μH, VDD = 5.0 V 3.3 mA
IN
= 0 V, load = 8 Ω + 33 μH, VDD = 3.6 V 2.9 mA
IN
= 0 V, load = 8 Ω + 33 μH, VDD = 2.5 V 2.4 mA
IN
SD
= GND
GAIN CONTROL
Closed-Loop Gain Gain 18 dB
Differential Input Impedance Z
IN
SD
= VDD
SHUTDOWN CONTROL
Input Voltage High V
Input Voltage Low V
Turn-On Time t
Turn-Off Time t
Output Impedance Z
WU
SD
IH
IL
OUT
ISY ≥ 1 mA 1.2 V
ISY ≤ 300 nA 0.5 V
SD
rising edge from GND to VDD
SD
falling edge from VDD to GND
SD
= GND
NOISE PERFORMANCE
Output Voltage Noise en V
= 3.6 V, f = 20 Hz to 20 kHz, inputs are
DD
ac-grounded, gain = 18 dB, A-weighted
Signal-to-Noise Ratio SNR PO = 1.4 W, RL = 8 Ω 96 dB
1
Although the SSM2335 has good audio quality above 3 W, continuous output power beyond 3 W must be avoided due to device packaging limitations.
2
This value represents measured performance; packaging limitations must not be exceeded.
1
Min Typ Max Unit
2
W
2
3.43
4.28
W
2
W
20 nA
20 kΩ
7 ms
5 μs
>100 kΩ
44 μV rms
Rev. 0 | Page 3 of 16
SSM2335
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ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings apply at 25°C, unless otherwise noted.
Table 2.
Parameter Rating
Supply Voltage 6 V
Input Voltage V
Common-Mode Input Voltage V
Continuous Output Power 3 W
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +85°C
Junction Temperature Range −65°C to +165°C
Lead Temperature (Soldering, 60 sec) 300°C
ESD Susceptibility 2.5 kV
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.
DD
DD
THERMAL RESISTANCE
θJA 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 PCB θJA θJB Unit
9-Ball, 1.5 mm × 1.5 mm WLCSP 1S0P 162 39 °C/W
2S0P 76 21 °C/W
ESD CAUTION
Rev. 0 | Page 4 of 16
SSM2335
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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
BALL A1
CORNER
A
B
C
SSM2335
TOP VIEW
BALL SIDE DOW N
(Not to Scale)
Figure 2. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1A IN+ Noninverting Input.
1B VDD Power Supply.
1C IN− Inverting Input.
2A GND Ground.
2B PVDD Power Supply.
2C
SD
Shutdown Input. Active low digital input.
3A OUT− Inverting Output.
3B GND Ground.
3C OUT+ Noninverting Output.
321
07551-002
Rev. 0 | Page 5 of 16
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