Other Parts Discussed in Thread: LM117
Tool/software:
Hello,
I would appreciate some help to better model the thermal analysis for the LM117 voltage regulator. I am particularly interested in transient analysis rather than steady-state analysis. Here is an example of my MATLAB script for evaluating the junction temperature.
% Simulation loop
for i = 2:length(time)
if time(i) <= t1
P = P1;
else
P = P2;
end
% Calculate temperature change using thermal RC model
dT = (P * dt) / C_th - (Tj - T_amb) * dt / (theta_JA * C_th);
Tj = Tj + dT;
temperature(i) = Tj;
end.
Where:
P1 is the peak power portion
P2 is the steady state power dissipation into the regulator
t1 is the time period where the surge/peak power is present
C_th is the thermal capacity of the TO-39 case + thermal adhesive + PCB
Theta_JA, the thermal resistance junction to ambiant
Here is a preliminary simulation result:
Thank you for your help
Best Regards
Bruno
