1.5W mono into 8Ω — the headline rating
The LM4861MX delivers 1.5W continuous into an 8Ω load from a single supply — enough to drive a small speaker or piezo in a portable audio alert or voice playback circuit. The Class AB output stage keeps crossover distortion low at low signal levels, which matters when the audio content is a voice prompt or tone, not just a beep.
Supply range and shutdown
Runs on 2V to 5.5V, so it works directly from a single Li-ion cell (3.6V nominal) or a 3.3V/5V regulated rail — no extra boost converter needed. The shutdown pin pulls the quiescent current to near zero when the amplifier is idle, extending battery life in duty-cycled applications like doorbells or handheld testers. Thermal protection is built in — the die-level sensor pulls back drive if the junction exceeds the safe limit, so a shorted output or blocked heatsink path doesn't instantly destroy the part. The SOIC-8 package relies on the PCB copper for heat spreading; a solid ground-plane pour under the body helps keep the junction below 150°C at full output.
Temperature grade and environment
The SOIC-8 body is standard reflow-compatible; no moisture-sensitive bake required if stored per JEDEC MSL-1 guidelines.