MPC8248VRTIEA Freescale Semiconductor, MPC8248VRTIEA Datasheet - Page 13

• Manufacturer Part Number: MPC8248VRTIEA
• Description: IC MPU POWERQUICC II 516-PBGA
• Manufacturer: Freescale Semiconductor

Specifications of MPC8248VRTIEA

• Processor Type: MPC82xx PowerQUICC II 32-bit
• Speed: 400MHz
• Voltage: 1.5V
• Mounting Type: Surface Mount
• Package / Case: 516-PBGA
• Family Name: MPC82XX
• Device Core: PowerQUICC II
• Device Core Size: 32b
• Frequency (max): 400MHz
• Instruction Set Architecture: RISC
• Supply Voltage 1 (typ): 1.5V
• Operating Supply Voltage (max): 1.575V
• Operating Supply Voltage (min): 1.425V
• Operating Temp Range: 0C to 105C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 516
• Package Type: TEPBGA
• For Use With: CWH-PPC-8248N-VE - KIT EVAL SYSTEM QUICCSTART 8248
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Compliant

where:
R
affect the case-to-ambient thermal resistance, R
the device, add a heat sink, change the mounting arrangement on the printed circuit board, or change the
thermal dissipation on the printed circuit board surrounding the device. This thermal model is most useful
for ceramic packages with heat sinks where some 90% of the heat flows through the case and the heat sink
to the ambient environment. For most packages, a better model is required.
4.3
A simple package thermal model which has demonstrated reasonable accuracy (about 20%) is a
two-resistor model consisting of a junction-to-board and a junction-to-case thermal resistance. The
junction-to-case thermal resistance covers the situation where a heat sink is used 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. It has
been observed that the thermal performance of most plastic packages, especially PBGA packages, is
strongly dependent on the board temperature.
If the board temperature is known, an estimate of the junction temperature in the environment can be made
using the following equation:
where:
If the board temperature is known and the heat loss from the package case to the air can be ignored,
acceptable predictions of junction temperature can be made. For this method to work, the board and board
mounting must be similar to the test board used to determine the junction-to-board thermal resistance,
namely a 2s2p (board with a power and a ground plane) and by attaching the thermal balls to the ground
plane.
4.4
When the board temperature is not known, a thermal simulation of the application is needed. The simple
two-resistor model can be used with the thermal simulation of the application, or a more accurate and
complex model of the package can be used in the thermal simulation.
Freescale Semiconductor
θJC
is device related and cannot be influenced by the user. The user adjusts the thermal environment to
R
R
R
R
T
P
D
B
θJA
θJC
θCA
θJB
Estimation with Junction-to-Board Thermal Resistance
Estimation Using Simulation
= board temperature (ºC)
= power dissipation in package
= junction-to-case thermal resistance (ºC/W)
= junction-to-board thermal resistance (ºC/W)
= junction-to-ambient thermal resistance (ºC/W)
= case-to-ambient thermal resistance (ºC/W)
R
T
θJA
J
= T
= R
B
+ (R
MPC8272 PowerQUICC II™ Family Hardware Specifications, Rev. 2
θJC
θJB
+ R
θCA
× P
D
)
θCA
. For instance, the user can change the air flow around
Thermal Characteristics
13