Heat flow in electronics - maximum power dissipate
Description
The heat flow can be modelled by analogy to an electrical circuit where heat flow is represented by current, temperatures are represented by voltages, heat sources are represented by constant current sources, absolute thermal resistances are represented by resistors and thermal capacitances by capacitors.
The diagram shows an equivalent thermal circuit for a semiconductor device with a heat sink
The formula says how much power can be put into the transistor before it overheats.
Related formulasVariables
| QMAX | power dissipated (W) |
| TJMAX | junction temperature (K) |
| TAMB | ambient air temperature (K) |
| ΔTHS | change in temperature (K) (K) |
| RJC | device's absolute thermal resistance from junction to case (K/W) |
| RB | absolute thermal resistance of the bond between the transistor's case and the metalwork (K/W) |
| RHA | absolute thermal resistance of the heat sink (K/W) |