SSM2377 Datasheet, PDF (1/16 Pages) Analog Devices – Filterless, High Efficiency, Mono 2.5 W Class-D Audio Amplifier Pop-and-click suppression

Filterless, High Efficiency,
Mono 2.5 W Class-D Audio Amplifier
SSM2377
FEATURES
Filterless, Class-D amplifier with spread-spectrum
Σ-Δ modulation
2.5 W into 4 Ω load and 1.4 W into 8 Ω load at 5.0 V supply
with <1% total harmonic distortion plus noise (THD + N)
92% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
>100 dB signal-to-noise ratio (SNR)
High PSRR at 217 Hz: 80 dB
Ultralow EMI emissions
Single-supply operation from 2.5 V to 5.5 V
Gain select function: 6 dB or 12 dB
Fixed input impedance of 80 kΩ
100 nA shutdown current
Short-circuit and thermal protection with autorecovery
Available in a 9-ball, 1.2 mm × 1.2 mm WLCSP
Pop-and-click suppression
APPLICATIONS
Mobile phones
MP3 players
Portable electronics
GENERAL DESCRIPTION
The SSM2377 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 2.5 W of continuous output power
with <1% THD + N driving a 4 Ω load from a 5.0 V supply.
The SSM2377 features a high efficiency, low noise modulation
scheme that requires no external LC output filters. The modu-
lation operates with high efficiency even at low output power.
The SSM2377 operates with 92% efficiency at 1.4 W into 8 Ω
from a 5.0 V supply and has an SNR of >100 dB.
Spread-spectrum pulse density modulation (PDM) is used to
provide lower EMI-radiated emissions compared with other
Class-D architectures. The inherent randomized nature of
spread-spectrum PDM eliminates the clock intermodulation
(beating effect) of several amplifiers in close proximity.
The SSM2377 produces ultralow EMI emissions that signifi-
cantly reduce the radiated emissions at the Class-D outputs,
particularly above 100 MHz. The SSM2377 passes FCC Class B
radiated emission testing with 50 cm, unshielded speaker cable
without any external filtering. The ultralow EMI emissions of the
SSM2377 are also helpful for antenna and RF sensitivity problems.
The device is configured for either a 6 dB or a 12 dB gain setting
by connecting the GAIN pin to the VDD pin or the GND pin,
respectively. Input impedance is a fixed value of 80 kΩ, indepen-
dent of the gain select operation.
The SSM2377 has a micropower shutdown mode with a typical
shutdown current of 100 nA. Shutdown is enabled by applying
a logic low to the SD pin.
The device also includes pop-and-click suppression circuitry,
which minimizes voltage glitches at the output during turn-on
and turn-off, reducing audible noise on activation and deactivation.
Built-in input low-pass filtering is also included to suppress out-
of-band noise interference to the PDM modulator.
The SSM2377 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 halide-free, 9-ball, 0.4 mm
pitch, 1.2 mm × 1.2 mm wafer level chip scale package (WLCSP).
FUNCTIONAL BLOCK DIAGRAM
AUDIO IN–
AUDIO IN+
22nF
22nF
SHUTDOWN
10µF
0.1µF
SSM2377
80kΩ
IN+
80kΩ
IN–
MODULATOR
(Σ-Δ)
POWER SUPPLY
2.5V TO 5.5V
VDD
FET
DRIVER
OUT+
OUT–
SD
BIAS
GAIN
INTERNAL
OSCILLATOR
POP/CLICK
AND EMI
SUPPRESSION
GND
GAIN SELECT
GAIN = 6dB OR 12dB
Figure 1.
Rev. 0
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