The TPA2031D1 is a 2.5-W high efficiency filter-free class-D audio power amplifier in a 1,45 mm × 1,45 mm wafer chip scale package (WCSP) that requires only three external components. Features like 88% efficiency, -75-dB PSRR, improved RF-rectification immunity, and 8 mm2 total PCB area make the TPA2031D1 class-D amp ideal for cellular handsets. 32 ms start-up time allows the TPA2031D1 to share the same GPIO enable/shutdown control as the CODEC without passing through the CODEC turn-on pop. In cellular handsets, the earpiece, speaker phone, and melody ringer can each be driven by the TPA2031D1. The TPA2031D1 allows independent gain while summing signals from separate sources, and has a low 36 µV noise floor, A-weighted.