Related Resources: heat transfer

Maximum Power Dissipation Transistor Equations and Calculator

Heat Transfer Engineering
Thermodynamics
Engineering Physics

Maximum Power Dissipation of a Transistor Equation and Calculator:

Assumptions:

1 Steady operating conditions exist.
2 The transistor case is isothermal at 85°C.

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Preview: Maximum Power Dissipation of a Transistor Calculator

 

Rate of heat transfer

Where:

Q = Heat Steady State Transfer (W)
R_case-ambient = Rated case-to-ambient thermal resistance (°C/W)
T_c = Transistor case temperature (°C)
T_∞ = Surrounding environment temperature (°C)

The transistor can be used at higher power levels by attaching it to a heat sink (which lowers the thermal resistance by increasing the heat transfer surface area, as discussed in the next example) or by using a fan (which lowers the thermal resistance by increasing the convection heat transfer coefficient).