This part is a kind of semiconductor called APL5606A.

Function of this product has Low Dropout 600mA Linear Regulator.

Manufacturers : ANPEC

Image and pinout :

Some of the text within the PDF file :

APL5606/A Low Dropout 600mA Linear Regulator for DC Fan Control Features General Description • Low Dropout Voltage: 220mV (typical) @ 600mA • Low Quiescent Current: 140µA • Selectable Adjustable/Full Speed Mode • O/I Voltage Ratio in Adjustable Mode : 1.6 times • Stable with Low ESR Ceramic Capacitors • Over-Temperature Protection • Current-Limit Protection with Foldback Current • Internal Soft-Start • SOP-8 Package • Lead Free and Green Devices Available (RoHS Compliant) Simplified Application Circuit VIN C1 1µF Adjustable mode Full speed mode VIN VOUT APL5606/A FSM GND VSE T VOUT C2 2.2µF Speed control voltage (VSET) The APL5606/A is a low quiescent current and low dropout linear regulator which is designed with a P-channel pass MOSFET to power a DC fa [ ... ]

APL5606A PDF Datasheet Download