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Heatsink calculations models the path from the junction (inside the chip/transistor) where heat is generated, to the air. This path is usual split in 3 parts.
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| Power | The power dissipated in the component |
| Rth j-c | Internal heat resistance of the component, see datasheet for component |
| Interface to heatsink | How the component is mounted on the heatsink |
| Package | Used to determine the surface between the component and the heatsink |
| Rth c-h | Heat resistance of interface |
| Air temperature | Air temperature around heatsink, this will typical 10-20 degrees above max. expected room temperature |
| Heatsink Rth h-a | Heat resistance of heatsink |
| Rth ch=0 | No heat resistance |
| Rth c-h | Specify your own heat resistance |
| Rth c-h for 1 cm² | Specify your own heat resistance |
| Rth c-h for 1 inch² | Specify your own heat resistance, this setting is used for most terminal interface pads |
| Direct mounting, dry | A typical value for dry mounting on a heatsink |
| Direct mounting, grease | A typical value for mounting with grease on a heatsink |
| all other | These are pads that can be used between the component and the heatsink to give a good thermal interface and in some cases also electric isolation |
| Heatsink temperature | Average temperature of the heatsink |
| Total power | The sum of power settings on panel #1 to #6 |
| Max. junction temp. | The highest junction temperatur from panel #1 to #6 |
| Component #x | Data from the specified panel |
| Rth j-c | Specified value |
| Thermal interface | Selected thermal interface |
| Rth c-h | Calculated heat resistance between case and heatsink |
| Temp. (junction) | Junction temperature of component on this pane |
| Interface to hot | This warning is shown for some of the predefined terminal pads, when the temperature is above their specified limit |