1.5W mono into 8Ω — the speaker-driver spec that matters
The Texas Instruments LM4991MAX/NOPB is a Boomer® series Class AB audio power amplifier delivering 1.5W into an 8Ω load from a single 2.2V to 5.5V supply. The part integrates depop circuitry to suppress turn-on/turn-off clicks, a low-power shutdown mode, and thermal protection — features aimed at battery-powered portable audio, speaker modules, and alert-tone generators where board space and BOM cost are tight.
Supply range and shutdown — battery-life decisions
The 2.2V to 5.5V supply range lets this amp run directly from a single Li-ion cell (3.0V–4.2V nominal) or a 3.3V/5.0V regulated rail. The shutdown pin (part of the feature set) pulls the quiescent current to near-zero when the audio path is idle — critical for extending standby life in a Bluetooth speaker or portable instrument. Thermal protection shuts the output stage before the die exceeds safe junction temperature, so a stalled speaker or high-ambient condition won't kill the part. The depop circuit ramps the output bias on startup, avoiding the thump that would otherwise couple through a small speaker.
Lifecycle: active, no LTB concern
It is ROHS3 compliant (lead-free).