mpc8378 Freescale Semiconductor, Inc, mpc8378 Datasheet - Page 115

• Manufacturer Part Number: mpc8378
• Description: Powerquicc Ii Pro Processor
• Manufacturer: Freescale Semiconductor, Inc

24.2
For the following sections, P
24.2.1
An estimation of the chip junction temperature, T
The junction to ambient thermal resistance is an industry-standard value that provides a quick and easy
estimation of thermal performance. Generally, the value obtained on a single layer board is appropriate for
a tightly packed printed circuit board. The value obtained on the board with the internal planes is usually
appropriate if the board has low power dissipation and the components are well separated. Test cases have
demonstrated that errors of a factor of two (in the quantity T
24.2.2
Freescale Semiconductor
Junction-to-package natural convection on top
Note:
1
2
3
4
5
6
Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board)
temperature, ambient temperature, air flow, power dissipation of other components on the board, and board thermal
resistance.
Per JEDEC JESD51-2 with the single layer board horizontal. Board meets JESD51-9 specification.
Per JEDEC JESD51-6 with the board horizontal.
Thermal resistance between the die and the printed circuit board per JEDEC JESD51-8. Board temperature is measured on
the top surface of the board near the package.
Thermal resistance between the die and the case top surface as measured by the cold plate method (MIL SPEC-883 Method
1012.1).
Thermal characterization parameter indicating the temperature difference between package top and the junction temperature
per JEDEC JESD51-2. When Greek letters are not available, the thermal characterization parameter is written as Psi-JT.
Thermal Management Information
Estimation of Junction Temperature with Junction-to-Ambient
Thermal Resistance
Estimation of Junction Temperature with Junction-to-Board
Thermal Resistance
The heat sink cannot be mounted on the package.
Table 81. Package Thermal Characteristics for TePBGA II (continued)
T
where:
MPC8377E PowerQUICC II Pro Processor Hardware Specifications, Rev. 3
J
= T
T
T
R
P
A
A
J
θ
D
+ (R
JA
= junction temperature (°C)
= ambient temperature for the package (°C)
= power dissipation in the package (W)
Parameter
D
= junction to ambient thermal resistance (°C/W)
θ
= (V
JA
× P
DD
D
)
× I
DD
) + P
NOTE
I/O
J
, can be obtained from the equation:
where P
J
I/O
–
T
is the power dissipation of the I/O drivers.
A
) are possible.
Symbol
ψ
JT
Value
6
°C/W
Unit
Notes
Thermal
6
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