Filterless High Efficiency
Class-D Stereo Audio Amplifier
SSM2302
Rev. 0
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FEATURES
Filterless Class-D amplifier with built-in output stage
1.4 W into 8 Ω at 5.0 V supply with less than 1% THD
85% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
Better 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 16-lead, 3 mm × 3 mm LFCSP
Pop-and-click suppression
Built-in resistors reduce board component count
Fixed and user-adjustable gain configurations
APPLICATIONS
Mobile phones
MP3 players
Portable gaming
Portable electronics
Educational toys
GENERAL DESCRIPTION
The SSM2302 is a fully integrated, high efficiency, Class-D stereo
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 5.0 V supply. It is capable of delivering 1.4 W of con-
tinuous output power with less than 1% THD + N driving an
8 Ω load from a 5.0 V supply.
The SSM2302 features a high efficiency, low noise modulation
scheme. It 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 better
than 98 dB. PDM modulation is used to provide lower EMI-
radiated emissions compared with other Class-D architectures.
The SSM2302 has a micropower shutdown mode with a typical
shutdown current of 20 nA. Shutdown is enabled by applying a
logic low to the SD pin.
The architecture of the device allows it to achieve a very low level
of pop and click. 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 SSM2302 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 VDD/2.
The SSM2302 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 utilizing the gain control
select pin connected respectively to ground or VDD. Gain can
also be adjusted externally by using an external resistor.
The SSM2302 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 a 16-lead, 3 mm × 3 mm
lead-frame chip scale package (LFCSP).
FUNCTIONAL BLOCK DIAGRAM
GAIN
CONTROL
FET
DRIVER
MODULATOR
0.1F
VDD
GND
INTERNAL
OSCILLATOR
OUTR+
OUTR–
OUTL+
OUTL–
GAIN
CONTROL
BIAS
FET
DRIVER
MODULATOR
INR+
VBATT
2.5V TO 5.0V
INR–
GAIN
SD
GAIN
SHUTDOWN
INL+
INL–
10F
0.01F1
1 INPUT CAPS ARE OPTIONAL IF INPUT DC COMMON-MODE
VOLTAGE IS APPROXIMATELY VDD/2.
0.01F1
LEFT IN+
LEFT IN–
RIGHT IN–
RIGHT IN+
SSM2302
06
05
1-
0
01
Figure 1.