Where PD is the power dissipated by the semiconductor device in watts, ΔT is the temperature differential, and θtotal is the sum of the thermal resistances. The subscript \(...Where PD is the power dissipated by the semiconductor device in watts, ΔT is the temperature differential, and θtotal is the sum of the thermal resistances. The subscript j stands for junction, c is for case (of the transistor), s is for heat sink and a is for the ambient air. Tj is the semiconductor junction temperature and is created by the product of the transistor's current and voltage.
