2 W Filterless Class-D

Stereo Audio Amplifier

Preliminary Technical Data

SSM2304

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FEATURES

Filterless Class-D amplifier with built-in output stage

2 W into 4 Ω and 1.2 W into 8 Ω at 5.0 V supply with less than

10% THD

85% efficiency at 5.0 V, 2W into 4 Ω speaker

Better than 95dB SNR (signal-to-noise ratio)

Available in 16-lead 3 mm × 3 mm LFCSP

Single-supply operation from 2.2 V to 5.0 V

20 nA ultralow shutdown current

Short-circuit and thermal protection

Pop-and-click suppression

Built-in resistors reduce board component count

Default fixed 18dB gain and user-adjustable

APPLICATIONS

Notebooks and PCs

Mobile phones

MP3 players

Portable gaming

Portable electronics

Educational toys

GENERAL DESCRIPTION

The SSM2304 is a fully integrated, high efficiency, Class-D stereo

audio amplifier. It is designed to maximize performance for

portable applications. The application circuit requires a

minimum of external components and operates from a single

2.2 V to 5.0 V supply. It is capable of delivering 2 W of con-

tinuous output power with less than 10% THD + N driving a

4 Ω load from a 5.0 V supply.

The SSM2304 features a high efficiency, low noise modulation

scheme. It operates with 85% efficiency at 2 W into 4 Ω from a

5.0 V supply and has a signal-to-noise ratio (SNR) that is better

than 95 dB. PDM modulation is used to provide lower EMI-

radiated emissions compared with other Class-D architectures.

The SSM2304 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 SSM2304 provides excellent

rejection of common-mode noise on the input. Input coupling

capacitors can be omitted if the dc input common-mode voltage

The SSM2304 also has excellent rejection of power supply noise,

including noise caused by GSM transmission bursts and RF

rectification. PSRR is typically 70 dB at 217 Hz.

The gain can be set to 6 dB or 18 dB utilizing the gain control

also be adjusted externally by using an external resistor.

The SSM2304 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).

Rev. PrD