Class AB mono amplifier for portable audio — 1W into 8Ω
The LM4889MAX/NOPB: Class AB topology gives a clean trade-off: lower crossover distortion than Class B and better efficiency than Class A, though not as power-efficient as Class D. For a battery-powered design where audio quality matters more than milliwatts of quiescent loss, this is the right choice. The built-in Depop circuitry suppresses the click and pop on power-up and shutdown — a feature that saves an external mute circuit on the BOM.
Supply voltage and output power — sizing the rail and speaker
Thermal Protection is included on-die: if the junction temperature exceeds the limit, the output stage reduces drive. In a sealed enclosure with limited airflow, this prevents catastrophic failure during a sustained high-volume test. The Shutdown pin lets a microcontroller put the amp into a low-power idle state when the audio path is silent, saving battery current.