The MAX9742ETX+T from Maxim Integrated is a Class D stereo audio amplifier delivering 20.5W per channel into an 8Ω load. It operates from a single 20V to 40V supply or split ±10V to ±20V rails, suiting it for powered speakers, soundbars, automotive aftermarket head units, and industrial audio paging systems where efficiency and compact board area matter. The 36-TQFN (6x6 mm) exposed-pad package and surface-mount footprint fit dense PCB layouts common in consumer and commercial audio products.
Supply voltage and output power — matching the load
Rated at 20.5W x 2 into 8Ω, this amplifier is sized for mid-power stereo applications — think 2.0-channel desktop speakers or ceiling-speaker zones in a commercial audio distribution system. The wide supply range (20V to 40V single, or ±10V to ±20V split) gives the designer flexibility: a 24V industrial supply rail works, as does a ±15V audio bench supply. The Class D topology keeps heat dissipation low enough that the exposed pad on the 36-TQFN can handle the thermal load without a separate heatsink in many chassis designs, though forced air or a larger copper plane is worth verifying at sustained full output.
Protection features and operating range
Integrated short-circuit and thermal protection reduce the chance of field failures in unattended equipment like digital signage players or PA amplifiers. The depop circuitry suppresses power-up/power-down thumps, which saves the BOM the cost of an external muting relay. The mute and shutdown pins give the system controller a way to silence the output during idle or fault conditions.