This part is a kind of semiconductor called SAP15N.

Function of this product has Darlington transistors with built-in temperature compensation diodes for audio amplifier applications.

Manufacturers : Sanken electric

Image and pinout :

Some of the text within the PDF file :

Darlington transistors with built-in temperature compensation diodes for audio amplifier applications SAPseries Features qBuilt-in temperature compensation diodes and one emitter resistor qReal time temperature compensation The temperature compensation diodes are mounted on one chip and placed in the center of the chip to detect temperature rises directly. qElimination of the temperature dependency of the idling current The temperature coefficient of the diodes is optimized to have the idling current stabilized; thus one of the fatal failure modes in conventional Darlington transistors, Thermal Runaway, is avoidable. qSymmetrical design for the PNP and the NPN pinouts The new design minimizes the length of the pattern layout, and output distortions are controlled. qDarlington transistors, [ ... ]

SAP15N PDF Datasheet Download