The TPA2037D1 is a 3.2 W high efficiency filter-free class-D audio power amplifier (class-D amp) with 6 dB of fixed gain in a 1.21 mm × 1.16 mm wafer chip scale package (WCSP). The device requires only one external component. Features like 95% efficiency, 1.5 mA quiescent current, 0.1 µA shutdown current, 81-dB PSRR, 20 µV output noise, and improved RF immunity make the TPA2037D1 class-D amplifier ideal for cellular handsets. A start-up time of 4 ms with no audible pop makes the TPA2037D1 ideal for PDA and smart-phone applications.