This post explains for the regulator.
The Part Number is APL5607.
The function of this semiconductor is 600mA Linear Regulator for DC Fan Speed Control.
Preview images :
The APL5607, APL5607A 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 and typical dropout voltage is only 220mV (typical) at 600mA output current. [ … ]
· Low Dropout Voltage: 220mV (Typical) @ 600mA
· Low Quiescent Current: 140mA
· Output Voltage / VSET Voltage: 1.6 Times
· Stable with Low ESR Ceramic Capacitors
· Over-Temperature Protection
· Current-Limit Protection with Foldback Current
· Notebook Fan Driver
· PC Peripherals
· Battery-Powered System