The FDC5614P is a P-channel enhancement-mode MOSFET from onsemi/Fairchild in SOT-223, rated at -60V drain-source voltage and -1.5A drain current with 600mOhm RDS(on) at VGS=-10V. The SOT-223 package provides better thermal performance than SOT-23: the large drain tab (pin 3) doubles as a heat-sinking surface, reducing thermal resistance to approximately 70C/W on a standard PCB. At VGS=-4.5V, RDS(on) increases to approximately 1.2Ohm, so the device is best suited for 5V or higher gate drive. The 60V rating makes it suitable for 12V, 24V, and 48V industrial bus high-side switching. As a P-channel MOSFET, it turns on when VGS < Vth (typically -2V): pulling the gate below the source voltage creates an inversion layer in the P-type body, forming a conductive channel. P-channel MOSFETs are preferred for high-side switching because no gate voltage above the supply is needed (unlike N-channel which requires a charge pump). The relatively high RDS(on) of 600mOhm limits this device to lower-current applications (<1A) where a small footprint is more important than conduction losses.