Class D audio amp with digital volume control — what this part does
Volume control is handled digitally over I²C or SPI, which means the gain is set in the digital domain — no analog pot, no wiper noise, and the setting survives a mute/unmute cycle. The part also includes a 3D enhancement, depop circuitry to suppress startup clicks, and thermal protection. The 25-bump WFBGA (uSMD) package keeps the footprint small for space-constrained PCBs like wireless earbuds, portable gaming devices, or compact IoT audio nodes.
Output power split — why the mono and headphone ratings matter
The 1.19W mono channel at 8Ω is sized for a small speaker in a portable dock or handheld device — think a Bluetooth speaker or a toy. The 87mW stereo headphone output at 32Ω covers standard consumer headphones. The split means a single IC handles both the speaker and the headphone jack, saving board space and BOM cost compared to using separate speaker amp and headphone amp ICs. If your design only needs a speaker, the headphone outputs can be left floating; if you need more headphone power, this part is not the right fit — look at a dedicated headphone amp instead.
I²C and SPI volume control — what it buys you
Digital volume control over I²C or SPI means the host microcontroller sets the gain in discrete steps, with no external potentiometer or variable resistor. The mute and shutdown functions are also bus-controlled, so the system can cut audio instantly without a separate GPIO. The depop feature ramps the output on startup to avoid the thump that otherwise hits the speaker — important for battery-powered devices where the amp is turned on and off frequently to save power.
Temperature range and environment
Rated for -40°C to 85°C ambient, this part is suited for industrial and outdoor portable equipment — think handheld test gear, outdoor audio beacons, or automotive cabin applications (non-safety). The Class D architecture keeps efficiency high, so heat dissipation is low even at full output, which helps in sealed enclosures.
Lifecycle and sourcing
The LM4947TLX/NOPB is listed as Active with ROHS3 compliance. No obsolescence notice or last-time-buy window is in effect. The part is available through independent distribution and is sourced to order against an RFQ — current pricing and lead time are confirmed at quote time. There is no official second-source or pin-compatible replacement listed; if you need an alternative, the closest functional match would be another Boomer® series Class D amp with I²C/SPI volume control, but verify the package and output power ratings against your BOM.