Calculating Temperature of a Device on a PCB (Part 2 of 4)

[@NickBinette]

These calculations are all based on an actual measurement. But what about when we don't have a PCB done yet? When we need to estimate the die temperature based on ambiant temp, when knowing the package, the Theta-JA (or JC, or JB, ...), and the approximate planned PCB layout?

[@vishnupriyatummala801]

Did you got the answer !! How?

[@geetarwanabe]

@@vishnupriyatummala801 you flip it... you solve what thermal dissipation you need to ensure your component with a known power output doesn't exceed a max operating junction temperature. If you are limited to your heatsink size then use that to calculate you junction temperature based on the component power output. This is all steady state calculations so you might exceed your max junction temperature but it could take 10 hours to do so based on the thermal mass of your system but this could then help define duty cycles of your components. Initially just worst case a steady state and if acceptable then it automatically works for transient states.