This part is a kind of semiconductor called APL5607A.

Function of this product has 600mA Linear Regulator for DC Fan Speed Control.

Manufacturers : ANPEC

Image and pinout :

Some of the text within the PDF file :

APL5607/A 600mA Linear Regulator for DC Fan Speed Control Features General Description • Low Dropout Voltage: 220mV (Typical) @ 600mA • Low Quiescent Current: 140µA • Enable/Shutdown Function • Output Voltage / VSET Voltage: 1.6 Times • Stable with Low ESR Ceramic Capacitors • Over-Temperature Protection • Current-Limit Protection with Foldback Current • Internal Soft-Start • SOP-8 and TDFN3x3-8 Packages • Lead Free and Green Devices Available (RoHS Compliant) Applications • Notebook Fan Driver • Motherboards • PC Peripherals • Battery-Powered System The APL5607/A is a low quiescent current and low dropout linear regulator which is designed to power a DC fan and deliver up to 600mA output current. The output voltage follows the 1.6 times of VSET voltage an [ ... ]

APL5607A PDF Datasheet Download