This part is a kind of semiconductor called KA3842AC.
Function of this product has SMPS Controller.
Manufacturers : Fairchild Semiconductor
Image and pinout :
Some of the text within the PDF file :
KA3842AC/KA3842AE SMPS Controller March 2006 KA3842AC/KA3842AE SMPS Controller Features Low start current 0.2mA (Typ.) Operating range up to 500kHz Cycle by cycle current limiting Under Voltage Lock Out (UVLO) with hysteresis Short shutdown delay time: Typ.100ns High current totem-pole output Output swing limiting: 22V Description The KA3842AC/KA3842AE are fixed PWM controllers for Off Line and DC to DC converter applications. The internal circuits include UVLO, low start up current, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem pole output for driving a POWER MOSFET. Also KA3842AC/KA3842AE provides low start up current below 0.3mA and short shutdown delay time, typically 100ns. The KA3842AC/KA3842AE [ ... ]