This part is a kind of semiconductor called TA8258H.

Function of this product has Dual Audio Power Amplifier.

Manufacturers : Toshiba

Image and pinout :

Some of the text within the PDF file :

TA8258H TOSHIBA Bipolar Linear Integrated Circuit Silicon Monolithic TA8258H Dual Audio Power Amplifier The TA8258H is dual audio power amplifier for consumer applications. This IC provides an output power of 20 watts per channel (at VCC = 37 V, f = 1kHz, THD = 10%, RL = 8 Ω). It is suitable for power amplifier of music center. Features · · · · · · · · High output power: Pout = 20 W/channel (Typ.) (VCC = 37 V, RL = 8 Ω, f = 1 kHz, THD = 10%) Low noise: Vno = 0.14 mVrms (Typ.) (VCC = 37 V, RL = 8 Ω, GV = 34dB, Rg = 10 kΩ, BW = 20 Hz~20 kHz) Very few external parts. Built in audio muting circuit. Built in thermal shut down protector circuit. Built in output shifted to GND protection circuit. (AC short) Available for using same PCB layout with: TA8200AH [ ... ]

TA8258H PDF Datasheet Download