mpc5553 Freescale Semiconductor, Inc, mpc5553 Datasheet - Page 8

• Manufacturer Part Number: mpc5553
• Description: Mpc5553 High Performance Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Electrical Characteristics
R
change the case-to-ambient thermal resistance, R
add a heat sink, change the mounting arrangement on printed circuit board, or change the thermal
dissipation on the printed circuit board surrounding the device. This description is most useful for
packages with heat sinks where 90% of the heat flow is through the case to the heat sink to ambient. For
most packages, a better model is required.
A more accurate two-resistor thermal model can be constructed from the junction-to-board thermal
resistance and the junction-to-case thermal resistance. The junction-to-case thermal resistance describes
when using a heat sink or where a substantial amount of heat is dissipated from the top of the package. The
junction-to-board thermal resistance describes the thermal performance when most of the heat is
conducted to the printed circuit board. This model can be used to generate simple estimations and for
computational fluid dynamics (CFD) thermal models.
To determine the junction temperature of the device in the application on a prototype board, use the
thermal characterization parameter (Ψ
temperature at the top center of the package case using the following equation:
The thermal characterization parameter is measured in compliance with the JESD51-2 specification using
a 40-gauge type T thermocouple epoxied to the top center of the package case. Position the thermocouple
so that the thermocouple junction rests on the package. A small amount of epoxy is placed on the
thermocouple junction and approximately 1 mm of wire extending from the junction. The thermocouple
wire is placed flat against the package case to avoid measurement errors caused by the cooling effects of
the thermocouple wire.
References:
Semiconductor Equipment and Materials International
805 East Middlefield Rd.
Mountain View, CA., 94043
[phone]
MIL-SPEC and EIA/JESD (JEDEC) specifications are available from Global Engineering Documents at
800-854-7179 or 303-397-7956.
JEDEC specifications are available on the web at http://www.jedec.org.
8
θJC
•
•
•
is device related and is not affected by other factors. The thermal environment can be controlled to
1. C.E. Triplett and B. Joiner, “An Experimental Characterization of a 272 PBGA Within an
Automotive Engine Controller Module,” Proceedings of SemiTherm, San Diego, 1998, pp. 47–54.
2. G. Kromann, S. Shidore, and S. Addison, “Thermal Modeling of a PBGA for Air-Cooled
Applications,” Electronic Packaging and Production, pp. 53–58, March 1998.
3. B. Joiner and V. Adams, “Measurement and Simulation of Junction to Board Thermal
Resistance and Its Application in Thermal Modeling,” Proceedings of SemiTherm, San Diego,
1999, pp. 212–220.
where:
T
T
Ψ
P
D
J
T
JT
= T
= thermocouple temperature on top of the package (
= power dissipation in the package (W)
= thermal characterization parameter (
T
+ (Ψ
JT
× P
MPC5553 Microcontroller Data Sheet, Rev. 2.0
D
)
JT
) to determine the junction temperature by measuring the
θCA
. For example, change the air flow around the device,
o
C/W)
o
C)
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