This part is a kind of semiconductor called IRFS640.

Function of this product has N-CHANNEL MOSFET.

Manufacturers : BLUE ROCKET ELECTRONICS

Image and pinout :

Some of the text within the PDF file :

IRFS640 Rev.D Mar.-2016 DATA SHEET 描述 / Descriptions TO-220F 塑封封装 N 沟道 MOS 场效应管。N-CHANNEL MOSFET in a TO-220F Plastic Package. 特征 / Features 低栅电荷,低反馈电容,开关速度快。 Low gate charge, low crss, fast switching. 用途 / Applications 用于高效 DC/DC 转换和功率开关。 These devices are well suited for high efficiency switching DC/DC converters and switch mode power supplies. 内部等效电路 / Equivalent Circuit 引脚排列 / Pinning 1 23 PIN1：G PIN 2：D PIN 3：S 放大及印章代码 / hFE Classifications & Marking 见印章说明。See Marking Instructions. http://www.fsbrec.com 1/6 IRFS640 Rev.D Mar.-2016 DATA SHEET 极限参数 / Absolute Maximum Ratings(Ta=25℃) 参数 Parameter Drain-Source Voltage [ ... ]

IRFS640 PDF Datasheet Download