
MPC8347E PowerQUICC II Pro Integrated Host Processor Hardware Specifications, Rev. 11
90
Freescale Semiconductor
Thermal
required in the heat sink. Minimize the size of the clearance to minimize the change in thermal
performance caused by removing part of the thermal interface to the heat sink. Because of the experimental
difficulties with this technique, many engineers measure the heat sink temperature and then back calculate
the case temperature using a separate measurement of the thermal resistance of the interface. From this
case temperature, the junction temperature is determined from the junction-to-case thermal resistance.
TJ = TC + (RθJC × PD)
where:
TJ = junction temperature (°C)
TC = case temperature of the package (°C)
RθJC = junction-to-case thermal resistance (°C/W)
PD = power dissipation (W)