This part is a kind of semiconductor called BLD123D.

Function of this product has NPN D SERIES TRANSISTORS.

Manufacturers : SI Semiconductors

Image and pinout :

Some of the text within the PDF file :

Free Datasheet http://www.Datasheet4U.com 深圳深爱半导体股份有限公司 Shenzhen SI Semiconductors Co., LTD. 产品规格书 Product Specification NPN D 系列晶体管/ D SERIES TRANSISTORS ●特点: 耐压高 开关速度快 安全工作区宽 符合 RoHS 规范 ●FEATURES：■HIGH VOLTAGE CAPABILITY ■HIGH SPEED SWITCHING ■WIDE SOA ●应用: 电子镇流器 节能灯 ●APPLICATIONS: ■ELECTRONIC BALLAST ■FLUORESCENT LAMP ●最大额定值（Tc=25°C） ●Absolute Maximum Ratings（Tc=25°C） TO-92/TO-92S 参数 PARAMETER 集电极-基极电压 Collector-Base Voltage 集电极-发射极电压 Collector-Emitter Voltage 发射极-基极电压 Emitter-Base Voltage 集电极电流 Collector Current 集电极耗散功率 Total Power Dissipation 最高工作温度 Ju [ ... ]

SFI0402ML120C PDF Datasheet Download