# 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 temperature View 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 sink View example Example 3: Must calculate the maximum power dissipation of a certain transistor mounted on to a 2°C/W heat sink View example
 Junction temperature °C Ambient temperature °C Power watts 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)