Class AB headphone driver with digital control
The LM48821TL/NOPB is a Texas Instruments Boomer® series Class AB stereo headphone amplifier in a 16-bump DSBGA package. It delivers 93 mW per channel into a 16 Ω load — enough to drive most consumer headphones to comfortable listening levels from a 2 V to 4 V supply rail. Class AB topology means the output stage operates in linear mode, avoiding the cross-over distortion of Class B while maintaining better efficiency than pure Class A. The trade-off is lower efficiency than a Class D amplifier — expect more heat dissipation in the package for the same output power.
I²C volume and feature set
An I²C interface provides volume control, mute, and shutdown — no external potentiometers or analog switches needed. The depop circuit suppresses the audible pop when the amplifier transitions from shutdown to active, a common annoyance in portable audio designs. Differential inputs reject common-mode noise picked up on the audio signal traces between the codec and the amplifier, which matters in a mixed-signal PCB where digital switching noise couples into analog paths.
Package and supply considerations
The 16-bump DSBGA (0.5 mm pitch) requires a PCB with fine-line routing and a solder mask defined pad layout. The small footprint saves board area but makes manual rework difficult — plan for optical inspection and X-ray of the solder joints during first-article validation. Supply range of 2 V to 4 V covers single-cell Li-ion (3.0-4.2 V) and two-cell alkaline (2.4-3.0 V) applications. Operating temperature from -40 °C to +85 °C suits both consumer portable devices and industrial audio equipment that sees temperature extremes.
ROHS3 compliant, with no restricted substances above the threshold limits. Suitable for new designs without obsolescence risk.