This part is a kind of semiconductor called APA2605.

Function of this product has 2.8W Stereo Class-D Audio Power Amplifier.

Manufacturers : ANPEC

Image and pinout :

Some of the text within the PDF file :

APA2605 2.8W Stereo Class-D Audio Power Amplifier (with DC Volume Control, AGC Function) Features • • • • • • • Operating Voltage: 3.3V-5.5V High Efficiency 85% at PO=2.8W, 4 Ω Speaker, VDD=5V Filter-Free Class-D Amplifier Low Shutdown Current – IDD=1µA at VDD=5V 64 Steps Volume Adjustable from -80dB to +20dB by DC Voltage with Hysteresis AGC (Non-Clip) Function Output Power at THD+N=1% – 2.3W at VDD=5V, RL=4Ω – 1.3W at VDD=5V, RL=8Ω Output Power at THD+N=10% – 2.8W at VDD=5V, RL=4Ω General Description The APA2605 is a stereo, high efficiency, filter-free ClassD audio amplifier available in SOP-18, SSOP-24, SSOP-24P, and QFN4x4-20A packages. The APA2605 provides the precise DC volume control, the gain range is from -80dB (V VOLUME =0V) to +20dB (VVOLUME=5V) [ ... ]

APA2605 PDF Datasheet Download