hi, TI
If developers measure the case temperature and the board temperature,
do they obtain the junction temperature from the equation below?
Thanks and Best Regards,
OHTA
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Hi, RJH
Thank you for your reply.
I confirmed SPRA953C”Semiconductor and IC Package Thermal Metrics”.
It says that the equation(Equation 4) is invalid.
Also, SPRA953C says that Ψjt should not be used when application of a heat sink is intended. Instead, Equation 5 and Equation 6 should be used.
but, I cannot measure θsa. so, I cannot calculate the junction temp by Equation 5 or Equation 6.
For that reason, I deduced that equation( I thought that equation with the idea of a two-resistance model)
which equation should I use for calculating correct junction temperature?
Spra953c says that Equation 4 is invaild.
Because, a very small percentage of heat energy in a typical plastic package is convected and radiated off the top surface of the package.
Tj [degC] = Tc [degC] + theta-jc [degC/W] * Pdiss [W] _______Equation 4
So, I deduced a equation below with the idea of two-resistance model.