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

0.1µF*

SD

AUDIO IN+

AUDIO IN–

SSM2319

40kΩ

160kΩ

160kΩ

40kΩ

FET

DRIVER

BIAS

INTERNAL

OSCILLATOR

SYNCI

SYNCO

SYNC INPUT

SYNC

Figure 1.