Stereo Class AB amplifier for portable and line-powered audio
The Texas Instruments LM4817MHX/NOPB is a Boomer® series Class AB stereo audio amplifier delivering 1.5W per channel into an 8Ω load from a 3V to 5.5V supply. It comes in a 28-lead HTSSOP package with an exposed thermal pad for heat sinking. Typical applications include portable speakers, docking stations, LCD monitors, and automotive head units where a simple linear audio stage is preferred over a switching Class D design.
Supply headroom and thermal budget
Rated for 3V to 5.5V, this part runs comfortably from a single lithium-ion cell or a regulated 5V rail. The datasheet's thermal resistance numbers (not reproduced here) guide the PCB copper area needed to keep the junction below 150°C at maximum ambient.
Built-in depop, shutdown, and thermal protection
The LM4817MHX/NOPB integrates pop-suppression circuitry (depop), a shutdown pin for power-save, and thermal-overload protection. The shutdown feature is active-low — pulling the pin low mutes the outputs and drops quiescent current to microamp levels. No external mute transistor or click-elimination RC network is needed for basic operation, though a small capacitor on the bypass pin (per the app note) further reduces turn-on transients.