This part is a kind of semiconductor called 78M09.

Function of this product has (78Mxx) 3-Terminal 0.5A Positive Voltage Regulator.

Manufacturers : Unisonic Technologies

Image and pinout :

Some of the text within the PDF file :

( DataSheet : ) UTC 78MXX LINEAR INTEGRATED CIRCUIT 3-TERMINAL 0.5A POSITIVE VOLTAGE REGULATOR DESCRIPTION The UTC 78MXX family is monolithic fixed voltage regulator integrated circuit. They are suitable for applications that required supply current up to 0.5 A. 1 TO-92 1 TO-126 FEATURES *Output current up to 0.5 A *Fixed output voltage of 5V, 6V, 8V, 9V, 12V, 15V ,18V and 24V available *Thermal overload shutdown protection *Short circuit current limiting *Output transistor SOA protection 1 TO-126C 1 TO-220 TO-92 TO-126/TO220 1: Output 2:GND 3: Input 1:Input 2:GND 3:Output *Pb-free plating product number: 78MXXL TEST CIRCUIT INPUT SERIES PASS ELEMENT 1 3 OUTPUT CURRENT GENERATOR SOA PROTECTION R20 STARTING CIRCUIT REFERENCE VOLTAGE ERROR AMPLIFIER [ ... ]

78M09 PDF Datasheet Download