2 W, Filterless, Class-D Stereo Audio Amplifier

The SSM2306 is a fully integrated, high efficiency, Class-D stereo audio amplifier designed to maximize performance for portable applications. The application circuit requires minimum external components and operates from a single 2.5 V to 5.0 V supply. It is capable of delivering 2 W of continuous output power with less than 10% total harmonic distortion plus noise (THD + N) driving a 4 Ω load from a 5.0 V supply.

The SSM2306 features an ultralow idle current, high efficiency, and a low noise modulation scheme. It operates with >87% efficiency at 1.4 W into 8 Ω from a 5.0 V supply and has a signal-to-noise ratio (SNR) that is better than 96 dB. Pulse-density modulation (PDM) offers lower electromagnetic interference (EMI) radiated emissions compared to other Class-D architectures.

The SSM2306 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 to minimize voltage glitches at the output during turn-on and turn-off, thereby reducing audible noise on activation and deactivation. The fully differential input of the SSM2306 provides excellent rejection of common-mode noise on the input. Input coupling capacitors can be omitted if the dc input common-mode voltage is approximately VDD/2.

The SSM2306 also has excellent rejection of power supply noise, including noise caused by GSM transmission bursts and RF rectification.

The SSM2306 has a preset gain of 18 dB that can be reduced by using external resistors.

The SSM2306 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).

APPLICATIONS

* Mobile phones

* MP3 players

* Portable gaming

* Portable electronics

* Educational toys

* Notebook computers

* Filterless Class-D amplifier with built-in output stage

* 2 W into 4 Ω and 1.4 W into 8 Ω at 5.0 V supply

* Ultralow idle current with load resistance

* >87% efficiency at 5.0 V, 1.4 W into 8 Ω speaker

* Better than 96 dB signal-to-noise ratio (SNR)

* Available in a 16-lead, 3 mm × 3 mm LFCSP