SSM2317 Datasheet, PDF (1/20 Pages) Analog Devices – Filterless High Efficiency Mono 3 W Class-D Audio Amplifier

Filterless High Efficiency
Mono 3 W Class-D Audio Amplifier
SSM2317
FEATURES
Filterless Class-D amplifier with Σ-Δ modulation
Automatic level control (ALC) improves dynamic range and
prevents clipping
3 W into 3 Ω load and 1.4 W into 8 Ω load at 5.0 V supply
with <10% total harmonic distortion (ALC off)
700 mW into 8 Ω load at 4.2 V supply (ALC 80%)
93% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
>93 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 SSM2317 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 SSM2317 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 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
>93 dB. Spread-spectrum pulse density modulation is used to
provide lower EMI radiated emissions compared with other
Class-D architectures.
Automatic level control (ALC) can be activated to suppress
clipping and improve dynamic range. This feature only requires
one external resistor tied to GND via the VTH pin and an
activation voltage on the ALC_EN pin.
The SSM2317 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 SSM2317 is 18 dB, but users can reduce the
gain by using a pair of external resistors (see the Gain section).
The SSM2317 is specified over the commercial 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
0.1µF¹
IN+
10kΩ
AUDIO IN+
80kΩ
0.1µF¹
IN–
AUDIO IN–
10kΩ
80kΩ
10µF
SSM2317
0.1µF
VDD
VBATT
2.5V TO 5.5V
MODULATOR
(Σ-Δ)
FET
DRIVER
OUT+
OUT–
SHUTDOWN
SD
BIAS
ALC
INTERNAL
OSCILLATOR
POP-AND-CLICK
SUPPRESSION
ALC_EN
VTH
GND
R_TH
ALC ENABLE
1 _{INPUT CAPACITORS ARE OPTIONAL IF INPUT DC COMMON-MODE}
VOLTAGE IS APPROXIMATELY V_DD/2.
Figure 1.
Rev. A
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