Filterless, High Efficiency,
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 modu-
lation 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.
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
The SSM2335 has a micropower shutdown mode with a typical
shutdown current of 20 nA. Shutdown is enabled by applying
SD
a logic low to the
pin.
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.
APPLICATIONS
Mobile phones
MP3 players
Portable gaming
Portable electronics
Educational toys
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 VDD/2.
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).
GENERAL DESCRIPTION
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).
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.
FUNCTIONAL BLOCK DIAGRAM
0.1µF
10µF
VBATT
2.5V TO 5.5V
VDD
SSM2335
160kΩ
47nF*
20kΩ
20kΩ
IN+
IN–
OUT–
OUT+
AUDIO IN+
AUDIO IN–
MODULATOR
FET
DRIVER
(Σ-Δ)
47nF*
160kΩ
SD
INTERNAL
OSCILLATOR
POP-AND-CLICK
SUPPRESSION
BIAS
SHUTDOWN
GND
*INPUT CAPACITORS ARE OPTIONAL IF INPUT DC COMMON-MODE
VOLTAGE IS APPROXIMATELY V /2.
DD
Figure 1.
Rev. 0
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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.
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