The BD677A is an NPN power transistor made by STMicroelectronics. It is designed for general purpose switching and amplifying applications. It has a maximum power dissipation of 4.5 watts, a collector-emitter voltage of 30V, and a collector current of 1.5A. It is a monolithic integrated circuit featuring high current gain and low saturation voltage. The BD677A also offers stress protection and higher reliability, and can be used in a wide range of applications, including inverters, switching power supplies, and motor control circuits.