PXS20 Datasheet, PDF (77/119 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Electrical characteristics
R_JC is device related and cannot be influenced by the user. The user controls the thermal environment to change the case to
ambient thermal resistance, R_CA. 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:
T_J = T_T + (_JT × P_D)
Eqn. 3
where:
T_T
= thermocouple temperature on top of the package (°C)
_JT = thermal characterization parameter (°C/W)
P_D
= 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
[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.
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.
3.5 Electromagnetic Interference (EMI) characteristics (cut1)
The characteristics in Table 13 were measured using:
• Device configuration, tet conditions, and EM testing per standard IEC61967-2
• Supply voltage of 3.3 V DC
• Ambient temperature of 25 C
The configuration information referenced in Table 13 is explained in Table 12.
PXS20 Microcontroller Data Sheet, Rev. 1
Freescale Semiconductor
77
Preliminary—Subject to Change Without Notice