The National Semiconductor LM4938MHX is a Boomer® series Class AB audio amplifier delivering 2.2W x 2 into a 3Ω load from a 5V supply. That 2.2W per channel figure is the headline rating that drives the speaker selection and the thermal design. Class AB topology gives you better linearity than Class D at the cost of lower efficiency — expect the exposed pad on the 28-HTSSOP package to need a solid thermal via stitch to the ground plane if you plan to sustain that output for more than a few seconds. The supply range of 2.7V to 5.5V means it runs comfortably from a single Li-ion cell or a 3.3V/5V regulated rail.
The RoHS compliance flag shows non-compliant — if your BOM requires RoHS-10/10, this part will not clear that gate, so check your exemption or plan for a lead-free alternate.
Rated for -20°C to 85°C ambient, which covers most indoor commercial and industrial equipment — think point-of-sale audio, intercoms, portable speakers, and conference-room sound bars. Not rated for automotive under-hood or outdoor telecom cabinets where -40°C excursions are common. The 28-TSSOP with exposed pad (HTSSOP) helps pull heat out of the die; a layout without the pad soldered to a copper pour will derate the output power well below the 2.2W figure.