MPC8347 FREESCALE [Freescale Semiconductor, Inc], MPC8347 Datasheet - Page 98

• Manufacturer Part Number: MPC8347
• Description: Integrated Host Processor Hardware Specifications
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Thermal
20.3.1
When a heat sink is used, the junction temperature is determined from a thermocouple inserted at the
interface between the case of the package and the interface material. A clearance slot or hole is normally
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.
98
Experimental Determination of the Junction Temperature with a
Heat Sink
MPC8347EA PowerQUICC II Pro Integrated Host Processor Hardware Specifications, Rev. 3
T
where:
J
= T
T
T
R
P
C
J
C
θ
D
+ (R
JC
= junction temperature (°C)
= case temperature of the package (°C)
= power dissipation (W)
= junction to case thermal resistance (°C/W)
θ
JC
× P
D
)
Freescale Semiconductor