Class D efficiency and output-stage architecture
The LM49450SQ/NOPB is a Class D stereo amplifier from the Boomer® family, delivering 2.5W per channel into a 4Ω load from a 2.7V–5.5V supply. Class D switching topology keeps quiescent losses low — important for battery-powered speakers where every milliwatt of idle current cuts into playtime. The output stage is configured as 2-channel (stereo) with a separate stereo headphone path, so a single IC drives both the main speakers and a headphone jack without an external mux.
Digital audio interface and system control
Digital audio enters via an I²S bus — the standard serial interface for codecs, DSPs, and Bluetooth audio modules. Volume, mute, 3D enhancement, and depop are set through an I²C control port, which also reports fault status from the short-circuit and thermal protection circuits. The depop feature suppresses the turn-on/turn-off thump that otherwise couples through the speaker. For a portable dock or smart speaker, this avoids the audible pop that users hear on power-up.
Thermal and layout for the 32-WQFN exposed pad
Housed in a 32-lead WFQFN with exposed pad (5×5 mm), the LM49450SQ/NOPB requires a thermal land on the PCB to sink heat from the Class D output stage. Surface-mount assembly follows standard QFN reflow profiles (MSL level not stated, but the exposed pad demands a solder paste stencil opening matching the datasheet land pattern). Tape & Reel or Cut Tape packaging is available for prototyping or production volume.