Class D mono amplifier for portable audio
The Texas Instruments LM4675SD/NOPB is a Class D mono audio amplifier from the Boomer® and PowerWise® series, delivering 2.7W into a 4Ω load from a single 2.4V to 5.5V supply. Typical applications include portable speakers, mobile phones, GPS units, and other battery-powered audio devices where efficiency and board space are tight.
The 2.7W output into 4Ω is the maximum continuous power before clipping at the rated supply and THD. For a 3.7V Li-ion battery, expect around 1.5W into 4Ω at lower distortion — still enough for a small enclosure. The 2.4V to 5.5V supply range covers single-cell Li-ion down to near-depletion and 5V USB rails, so the amplifier keeps running as the battery sags.
The NOPB suffix confirms lead-free soldering compatibility with standard reflow profiles.