The BC817-40 from Hottech is a PNP Bipolar Junction Transistor (BJT) in a SOT-23-3 (Small Outline Transistor-23) package. It is RoHS compliant and has a rated voltage of 45V, a rated current of 500mA, and a typical transition frequency of 270MHz. It has a maximum power dissipation of 500mW when mounted on a printed circuit board. The transistor features three terminals (collector, base, and emitter) that can be used to control, amplify, and switch electrical signals in various types of circuits and electronic devices. It is commonly used in amplifiers, logic gates, oscillators, suppressors, motor drivers, and other applications requiring analog and/or digital signals.