Heat sink calculator

Calculates thermal properties of a power device mounted on a heat sink

Example 1: Must calculate the thermal resistance of a heat sink to keep the junction temperature under 140 degrees celsius at 30 watt power dissipation when using IRFZ44 mosfet in a maximum of 60 degrees ambient temperatureView example
Example 2: Must calculate the junction temperature of a mosfet at 50 watt dissipation when mounted on to a 0.8°C/W heat sinkView example
Example 3: Must calculate the maximum power dissipation of a certain transistor mounted on to a 2°C/W heat sinkView example
Junction temperature°C
Ambient temperature°C
Junction-case resistance°C/W
Case-sink resistance°C/W
Sink-ambient resistance°C/W
You may use one of the following SI prefix after a value: p=pico, n=nano, u=micro, m=milli, k=kilo, M=mega, G=giga

Fill in all values except the one you wish to calculate
  • Junction temperature - Junction temperature at a given power
  • Ambient temperature - Ambient temperature of the surrounding air
  • Power - Power dissipated in device
  • Junction-case resistance - Thermal resistance from junction to case (RthJC)
  • Case-sink resistance - Thermal resistance from case to sink (RthCS) (including thermal interface material)
  • Sink-ambient resistance - Thermal resistance from sink to ambient (RthSA) (heat sink performance)