Class AB headphone driver for battery-powered audio
The LM4922TL/NOPB is a Texas Instruments Boomer® series Class AB audio amplifier designed to drive stereo headphones directly from a single lithium-ion cell. Rated 80 mW per channel into a 16 Ohm load, this part delivers enough level for consumer headphones without the crossover distortion of a Class B stage or the switching noise of a Class D. The Class AB topology keeps the output devices conducting through the zero-crossing region, so the distortion floor stays low at low listening levels — the real advantage over a Class D part in a quiet playback environment.
The 14-WFBGA (DSBGA) package is a wafer-level chip-scale ball grid array — the die itself is the package, with solder balls directly on the silicon pads. There is no plastic overmold, so the part is thin (under 1 mm seated height) but the balls are small and the pitch is tight. A hot-air rework station with a fine nozzle can handle it, but the board needs a solder mask defined pad pattern matching the TI recommended land layout. The part orientation mark is a small dot on the top surface — locate it under magnification before placing. Because the backside of the die is exposed, the package is sensitive to mechanical stress from board flex. Mount it near a stiffening feature or in a region of the PCB that sees minimal bending during assembly and field use.
Active production and compliance
The ROHS3 compliance (exemption-free) means no restricted substances above the threshold limits — no lead, no phthalates, no conflict minerals reporting issues for global shipments. If a BOM hedge is needed, the parametric search within TI's Boomer® family would target another Class AB headphone amp in a similar supply voltage and output power range, but the DSBGA footprint is specific to this part — a board spin would be required for any alternative package.