The SSM2375 is a fully integrated, high efficiency, Class-D audioamplifier. It is designed to maximize performance for mobilephone applications. The application circuit requires a minimumof external components and operates from a single 2.5 V to 5.5 Vsupply. It is capable of delivering 3 W of continuous output powerwith <1% THD + N driving a 3 Ω load from a 5.0 V supply.

The SSM2375 features a high efficiency, low noise modulationscheme that requires no external LC output filters. The modulationcontinues to provide high efficiency even at low output power.The SSM2375 operates with 93% efficiency at 1.4 W into 8 Ωor with 85% efficiency at 3 W into 3 Ω from a 5.0 V supply andhas an SNR of >100 dB.

Spread-spectrum pulse density modulation (PDM) is used toprovide lower EMI-radiated emissions compared with otherClass-D architectures. The inherent randomized nature ofspread-spectrum PDM eliminates the clock intermodulation(beating effect) of several amplifiers in close proximity.

The SSM2375 includes an optional modulation select pin(ultralow EMI emissions mode) that significantly reduces theradiated emissions at the Class-D outputs, particularly above100 MHz. In ultralow EMI emissions mode, the SSM2375can pass FCC Class B radiated emission testing with 50 cm,unshielded speaker cable without any external filtering.

The device also includes a highly flexible gain select pin thatallows the user to select a gain of 0 dB, 3 dB, 6 dB, 9 dB, or12 dB. The gain selection feature improves gain matchingbetween multiple SSM2375 devices within a single applicationas compared to using external resistors to set the gain.

The SSM2375 has a micropower shutdown mode with a typicalshutdown current of 20 nA. Shutdown is enabled by applyinga logic low to the SD pin.

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

Other features that simplify system-level integration of theSSM2375 include input low-pass filtering to suppress out-of-bandDAC noise interference to the PDM modulator and fixed-inputimpedance to simplify component selection across multipleplatform production builds.

The SSM2375 is specified over the industrial temperature rangeof −40°C to +85°C. It has built-in thermal shutdown and outputshort-circuit protection. It is available in a halide-free, 9-ball,1.5 mm × 1.5 mm wafer level chip scale package (WLCSP).

Applications

• Mobile phones
• MP3 players
• Portable electronics

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.