MPC5643L datasheet(62/98 Pages) FREESCALE

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MPC5643L Microcontroller Data Sheet, Rev. 3

Preliminary—Subject to Change Without Notice

Electrical characteristics

Freescale Semiconductor

RθJC is device related and cannot be influenced by the user. The user controls the thermal environment to change the case to

ambient thermal resistance, RθCA. For instance, the user can change the size of the heat sink, the air flow around the device, the

interface material, the mounting arrangement on printed circuit board, or change the thermal dissipation on the printed circuit

board surrounding the device.

To determine the junction temperature of the device in the application when heat sinks are not used, the Thermal

Characterization Parameter (

JT) can be used to determine the junction temperature with a measurement of the temperature at

the top center of the package case using Equation 3:

TJ =TT +(ΨJT ×PD)

Eqn. 3

where:

= thermocouple temperature on top of the package (°C)

= thermal characterization parameter (°C/W)

= power dissipation in the package (W)

The thermal characterization parameter is measured per JESD51-2 specification using a 40 gauge type T thermocouple epoxied

to the top center of the package case. The thermocouple should be positioned so that the thermocouple junction rests on the

package. A small amount of epoxy is placed over the thermocouple junction and over about 1 mm of wire extending from the

junction. The thermocouple wire is placed flat against the package case to avoid measurement errors caused by cooling effects

of the thermocouple wire.

3.4.1.1

References

Semiconductor Equipment and Materials International

3081 Zanker Road

San Jose, CA 95134 USA

(408) 943-6900

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.

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.

MPC5643L Datasheet(PDF) 62 Page - Freescale Semiconductor, Inc