1. Description
These N-Channel enhancement mode power field effect transistors are produced using Fairchild’s proprietary, 
planar, DMOS technology. This advanced technology has been especially tailored to minimize on-state resistance, 
provide superior switching performance, and withstand high energy pulse in the avalanche and commutation mode. 
These devices are well suited for high efficiency switching DC/DC converter and switch mode power supplies.
2.  Features 
>14A, 250V, RDS(on) = 0.28Ω @VGS = 10 V
>Low gate charge ( typical 47 nC)
>Low Crss ( typical 30 pF)
>Fast switching
>100% avalanche tested
>Improved dv/dt capability
https://www.utsource.net/ic-datasheet/IRFW644B-1886268.html