MPC8247 MOTOROLA [Motorola, Inc], MPC8247 Datasheet - Page 11

• Manufacturer Part Number: MPC8247
• Description: MPC8272 PowerQUICC II Family Hardware Specifications
• Manufacturer: MOTOROLA [Motorola, Inc]

4
Table 6 describes thermal characteristics. Refer to Table 2 for information on a given device’s package.
Discussions of each characteristic are provided in sections 4.1 through 4.7. For the these discussions, P
(V
1
2
3
4
4.1
An estimation of the chip junction temperature, T
where:
The junction-to-ambient thermal resistance is an industry standard value which provides a quick and easy
estimation of thermal performance. However, the answer is only an estimate; test cases have demonstrated
that errors of a factor of two (in the quantity T
MOTOROLA
Junction-to-ambient—
single-layer board
Junction-to-ambient—
four-layer board
Junction-to-board
Junction-to-case
Junction-to-package top
Assumes no thermal vias
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.
DD
I
T
R
P
DD
A
D
Thermal Characteristics
JA
= ambient temperature (ºC)
= power dissipation in package
) + PI/O, where PI/O is the power dissipation of the I/O drivers.
Estimation with Junction-to-Ambient Thermal
Resistance
= package junction-to-ambient thermal resistance (ºC/W)
T
3
Characteristic
J
2
1
= T
MPC8272 PowerQUICC II™ Family Hardware Specifications
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
A
4
+ (R
Freescale Semiconductor, Inc.
For More Information On This Product,
JA
Table 6. Thermal Characteristics
P
D
Go to: www.freescale.com
)
J
– T
J
, in °C can be obtained from the equation:
Symbol
A
R
R
R
R
R
) are possible.
JC
JA
JA
JB
JT
Value
27
21
19
16
11
8
2
Unit
C/W
C/W
C/W
C/W
C/W
Thermal Characteristics
Natural convection
Natural convection
Air Flow
1 m/s
1 m/s
—
—
—
D
11
=