MPC5553EVB Freescale Semiconductor, MPC5553EVB Datasheet - Page 7

• Manufacturer Part Number: MPC5553EVB
• Description: KIT EVAL MPC5553MZP132
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC5553EVB

• Contents: Eval Board and Demo Software
• Processor To Be Evaluated: MPC55xx
• Data Bus Width: 32 bit
• Interface Type: RS-232, Ethernet
• For Use With/related Products: MPC5553
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Connect all the ground and power balls to the respective planes with one via per ball. Using fewer vias to
connect the package to the planes reduces the thermal performance. Thinner planes also reduce the thermal
performance. When the clearance between the vias leave the planes virtually disconnected, the thermal
performance is also greatly reduced.
As a general rule, the value obtained on a single-layer board is within the normal range for the tightly
packed printed circuit board. The value obtained on a board with the internal planes is usually within the
normal range if the application board has:
The thermal performance of any component depends on the power dissipation of the surrounding
components. In addition, the ambient temperature varies widely within the application. For many natural
convection and especially closed box applications, the board temperature at the perimeter (edge) of the
package is approximately the same as the local air temperature near the device. Specifying the local
ambient conditions explicitly as the board temperature provides a more precise description of the local
ambient conditions that determine the temperature of the device.
At a known board temperature, the junction temperature is estimated using the following equation:
When the heat loss from the package case to the air does not factor into the calculation, an acceptable value
for the junction temperature is predictable. Ensure the application board is similar to the thermal test
condition, with the component soldered to a board with internal planes.
The thermal resistance is expressed as the sum of a junction-to-case thermal resistance plus a
case-to-ambient thermal resistance:
R
change the case-to-ambient thermal resistance, R
add a heat sink, change the mounting arrangement on the printed circuit board, or change the thermal
Freescale Semiconductor
θJC
•
•
•
•
•
is device related and is not affected by other factors. The thermal environment can be controlled to
Quality of the thermal and electrical connections to the planes
Power dissipated by adjacent components
One oz. (35 micron nominal thickness) internal planes
Components are well separated
Overall power dissipation on the board is less than 0.02 W/cm
where:
where:
T
T
T
R
P
R
R
R
R
D
J
J
B
θJB
θJA
θJA
θJC
θCA
= T
= junction temperature (
= board temperature at the package perimeter (
= power dissipation in the package (W)
= junction-to-board thermal resistance (
= junction-to-case thermal resistance (
= R
= junction-to-ambient thermal resistance (
= case-to-ambient thermal resistance (
B
+ (R
θJC
θJB
+ R
× P
θCA
MPC5553 Microcontroller Data Sheet, Rev. 3.0
D
)
o
C)
θCA
. For example, change the air flow around the device,
o
o
C/W)
o
C/W)
C/W) per JESD51-8
o
C/W)
o
C/W)
2
Electrical Characteristics
7