Class D audio amp in a 20-bump uSMD
The Texas Instruments LM49150TLX/NOPB is a Boomer® series Class D audio amplifier that delivers 2.1W into a 4Ω mono speaker load while simultaneously driving 42mW per channel into 32Ω stereo headphones from a single 2.7V to 5.5V supply. The output configuration — a mono speaker channel plus a separate stereo headphone channel — means a single IC handles both the main transducer and the headphone jack in portable audio products, eliminating a second amplifier IC. The 20-bump UFBGA package (supplier device package 20-uSMD) keeps the footprint under 4 mm², suiting it for space-constrained designs like smartphones, tablets, and portable gaming devices where board area is at a premium.
The 2.1W into 4Ω at the mono output is the Class D speaker channel's maximum continuous power — enough to drive a small internal speaker to audible levels in a handheld device without an external power stage. The 42mW per channel into 32Ω headphone output is a line-level headphone driver, not a high-power headphone amp — it drives standard earbuds or low-impedance headphones to comfortable listening levels but will clip with high-impedance studio monitors. The Class D architecture means the speaker channel operates at >85% efficiency at full power, so the 2.1W output draws roughly 2.5W from the battery — the thermal dissipation in the 20-uSMD package stays manageable without a heatsink.
Feature set for audio system integration
The integrated depop circuitry suppresses the pop and click noise that normally occurs when the amplifier powers up or switches modes — this eliminates the need for external muting FETs or series capacitors on the output. The I²C control interface allows volume adjustment, mute, shutdown, and E²S (Enhanced EMI Suppression) configuration from the system processor, saving GPIO pins compared to a parallel-controlled amplifier. Thermal protection shuts down the amplifier if the die temperature exceeds the safe operating limit — in a portable device this prevents the plastic package from softening or the solder joints from fatiguing under sustained high-power playback.
Temperature grade and operating environment
The 2.7V to 5.5V supply range covers single-cell Li-ion (3.0-4.2V), two-cell alkaline (3.0V), and regulated 5V USB rails — no external boost converter is needed for the amplifier supply in most battery-powered designs.
The ROHS3 compliance covers the full substance restriction list including the four phthalates — the part ships without exemption declarations needed for EU or California market entry.