Filterless, High Efficiency,
Mono 3 W Class-D Audio Amplifier
SSM2319
Rev. 0
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FEATURES
Filterless Class-D amplifier with ultraefficient spread-
spectrum Σ-Δ modulation
Internal modulator synchronization (SYNC)
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)
90% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
Signal-to-noise ratio (SNR): 98 dB
Single-supply operation: 2.5 V to 5.5 V
Ultralow shutdown current: 20 nA
Short-circuit and thermal protection with autorecovery
Available in 9-ball, 1.5 mm × 1.5 mm WLCSP
Pop-and-click suppression
Built-in resistors reduce board component count
Default fixed 12 dB or user-adjustable gain setting
APPLICATIONS
Mobile phones
MP3 players
Portable gaming
Portable electronics
Educational toys
GENERAL DESCRIPTION
The SSM2319 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.
The SSM2319 features a high efficiency, low noise modulation
scheme that does not require any external LC output filters. The
modulation continues to provide high efficiency even at low output
power. It operates with 90% 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 98 dB. Spread-spectrum pulse density modulation is used to
provide lower EMI-radiated emissions compared with other
Class-D architectures.
SYNC can be activated in the event that end users are concerned
about clock intermodulation (beating effect) of several amplifiers in
close proximity.
The SSM2319 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 device also includes pop-and-click suppression circuitry.
This minimizes voltage glitches at the output during turn-on and
turn-off, reducing audible noise on activation and deactivation.
The default gain of the SSM2319 is 12 dB, but users can reduce
the gain by using a pair of external resistors (see the Gain section).
The SSM2319 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).
FUNCTIONAL BLOCK DIAGRAM
SHUTDOWN
0.1µF
VDD
POP/CLICK
SUPPRESSION
OUT+
OUT–
IN–
VBATT
2.5V TO 5.5V
IN+
MODULATOR
(
Σ
-
Δ
)
GND
SYNC OUTPUT
10µF
0.1µF*
*INPUT CAPACITORS ARE OPTIONAL IF INPUT DC COMMON-MODE
VOLTAGE IS APPROXIMATELY V
DD
/2.
0.1µF*
SD
AUDIO IN+
AUDIO IN–
SSM2319
40k
Ω
160k
Ω
160k
Ω
40k
Ω
FET
DRIVER
BIAS
INTERNAL
OSCILLATOR
07
55
0-
00
1
SYNCI
SYNCO
SYNC INPUT
SYNC
Figure 1.