3W into 3Ω — the output rating that sets the application
The LM4871MMX/NOPB is a Texas Instruments Boomer® series Class AB audio amplifier delivering 3W into a 3Ω load from a single channel. That 3W figure is the headline spec — it tells you this part is sized for a small speaker or transducer in a portable or battery-powered device, not a line-level preamp or a multi-channel home audio system.
Supply rails: 2V to 5.5V — fits 3.3V and 5V systems
The supply range runs from 2V to 5.5V, which means it runs cleanly off a single 3.3V or 5V rail without needing a separate audio supply. That simplifies the power tree on a portable PCB — one regulator feeds both the digital core and this amplifier. At 3.3V the output power will be lower than the rated 3W at 3Ω, but the part still operates within its linear region.