2 x 2 W, Filterless, Stereo, Class-D Audio Amplifier with ALC + IC

The SSM2380 is a fully integrated, high efficiency, stereo, 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 W of continuous output power with <1% THD + N driving a 4 Ω load from a 5.0 V supply.

The SSM2380 features a highly flexible I2C interface with many useful settings. Using the I2C control interface, the gain of the SSM2380 can be selected from 1 dB to 24 dB (plus mute) in 47 steps with no external components. Other features accessed from the I2C interface include independent left/right channel shutdown, variable ultralow EMI emission control mode, auto-matic level control (ALC) for high quality speaker protection, and stereo-to-mono mixing operation.

The SSM2380 features a high efficiency, low noise modulation scheme that requires no external LC output filters. The modulation continues to provide high efficiency even at low output power. The SSM2380 operates with 93% efficiency at 1.4 W into 8 Ω or with 85% efficiency at 2 W into 4 Ω from a 5.0 V supply and has an SNR of >100 dB.

Spread-spectrum pulse density modulation is used to provide lower EMI-radiated emissions compared with other Class-D architectures. An added benefit of spread-spectrum Σ-Δ modu-lation is that no synchronization (SYNC) is needed when using multiple Class-D amplifiers. For applications that require long speaker cables (>10 cm), the SSM2380 includes a user-selectable ultralow EMI emissions mode that eliminates the need for EMI filters at the Class-D outputs.

The SSM2380 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 or through an optional independent channel soft shutdown via I2C.

The device also includes pop-and-click suppression circuitry. This suppression circuitry minimizes voltage glitches at the output during turn-on and turn-off, reducing audible noise on activation and deactivation.

The fully differential inputs of the SSM2380 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 SSM2380 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-ball, 2 mm × 2 mm wafer level chip scale package (WLCSP).

Applications

* Mobile phones

* MP3 players

* Portable electronics

* Filterless, stereo, Class-D amplifier with Σ-Δ modulation

* 2 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)

* Highly configurable I2C interface for gain adjust, automatic level control (ALC), and ultralow EMI emissions mode

* MODE pin can disable I2C interface for more traditional stereo amplifier configuration

* Stereo-to-mono mixer option via I2C control

* 93% efficiency at 5.0 V, 1.4 W into 8 Ω speaker

* Signal-to-noise ratio (SNR): >100 dB

* Single-supply operation from 2.5 V to 5.5 V

* Ultralow shutdown current: 20 nA

* Short-circuit and thermal protection

* Pop-and-click suppression

* Available in 16-ball, 2.0 mm × 2.0 mm WLCSP