Transistor Specifications
Power Dissipation Rating (Pd(max))

The Power Dissipation Rating is the maximum power that a transistor can handle across its collector-emitter junction.

The power that is dissipated across this collector-emitter region depends on voltage, VCE, which is the voltage that drops across the collecter-emitter junction, and current, Ic, which is the current that flows across this junction. The product of VCE and IC makes up the power that is dissipated across the collector-emitter junction.

Pd= VCE X Ic

The product VCE X Ic must not exceed the maximum power dissipation rating, Pd(max), of the transistor.