15W per channel high-integration class-D filter-less audio amp, from ADI

July 26, 2016 // By Graham Prophet
Analog Device recently posted details of the SSM3582, a fully integrated, high efficiency, digital input stereo Class-D audio amplifier. It can operate from a single supply, and requires only a few external components, significantly reducing the circuit bill of materials.

A proprietary, spread spectrum Σ-Δ modulation scheme enables direct connection to the speaker, and optiises analogue performance while lowering radiated emissions compared to other Class-D architectures. An optional ultra-low electromagnetic interference (EMI) mode significantly reduces radiated emissions above 100 MHz, enabling longer speaker cable lengths. Audio is transmitted digitally to the amplifier, minimizing the possibility of signal corruption in digital environments. The amplifier provides analog performance of over 106 dB signal-to-noise ratio and THD + N of 0.004%.


The SSM3582 operates from a single 4.5V to 16V supply, and is capable of delivering 2 × 15 W rms continuously into 8Ω and 4Ω loads at <1% total harmonic distortion (THD). The efficient modulation scheme maintains power efficiency over a wide range of impedances: 93% into an 8Ω load and 90% into a 4Ω load. Optimization of the output pulse maintains performance at impedances as low as 3Ω/5 μH, enabling its use with extended bandwidth tweeters. A mono mode is permitted, paralleling the two channels to increase drive to one speaker.

The pulse code modulation (PCM) audio serial port supports most common protocols, such as I ²S, left justified, and time division multiplexing (TDM), and can address up to 16 devices on a single interface, for up to 32 audio playback channels. IC operation is controlled through a dedicated I ²C interface. A micropower shutdown mode is triggered by removing the digital audio interface clock, with a typical current of <1 μA. A software power-down mode is also available.


An automatic power-down feature shuts down the amplifier and the digital-to-analog converter (DAC) when no signal is present at the input, minimizing power consumption during digital silence. The device restarts when nonzero data is present at the input. Mute and unmute transitions are pop/click free.


The SSM3582 is specified over the commercial temperature range of −40°C to +85C. The device has built-in thermal shutdown and output short-circuit