Analog Devices’ Class-D Audio Amplifiers Reduce Design Complexity and Enhance Sound Quality in Portable Electronics

The SSM2380 low-power, stereo Class-D amplifier is the first in its class to incorporate an I²C interface, which allows gain stages to be set from 1 dB to 24 dB (plus mute) in 47 distinct steps with no other external components required. The programmable interface also enables independent L/R channel shutdown, a variable low-EMI (electro-magnetic interference) emission control mode, and programmable ALC (automatic level control) functions for speaker protection. The SSM2380 achieves a 100-dB SNR (signal-to-noise ratio) and extends battery life by achieving 93 percent power efficiency at 5 V while running at 1.4 W into an 8-ohm speaker.

The SSM2375 is a high-performance, fully-integrated Class-D amplifier with single-pin 5-level gain setting in 3-dB stages from 0 dB to 12 dB. The single-pin gain setting eliminates input resistors and ensures a better input match that reduces noise and improves audio quality. Operating from a single 2.5-V to 5-V supply, the amplifier delivers 3 W of continuous output power with less than 1 percent THD (total harmonic distortion) when driving a 3-ohm load from a 5-V supply.

The SSM2375 offers greater than 98-dB SNR performance and at 215 Hz achieves an 80-dB PSRR (power-supply rejection ratio) that is 10 dB higher than the closest competing Class-D amplifier. The amplifier’s low noise and EMI allow engineers more flexibility to place the speaker on the board in end product designs.