mcf54455 Freescale Semiconductor, Inc, mcf54455 Datasheet - Page 18

• Manufacturer Part Number: mcf54455
• Description: 32-bit Microprocessor With Usb On-the-go, Ethernet, Pci, Ddr2/ddr Controller And Encryption
• Manufacturer: Freescale Semiconductor, Inc

Electrical Characteristics
5.2
The average chip-junction temperature (T
Where:
For most applications P
Solving equations 1 and 2 for K gives:
18
1
2
3
4
5
Junction to ambient, natural convection
Junction to ambient (@200 ft/min)
Junction to board
Junction to case
Junction to top of package
Maximum operating junction temperature
T
Q
P
P
P
A
JMA
D
INT
I/O
θ
Freescale recommends the use of θ
device junction temperatures from exceeding the rated specification. System designers should be aware that
device junction temperatures can be significantly influenced by board layout and surrounding devices.
Conformance to the device junction temperature specification can be verified by physical measurement in the
customer’s system using the Ψ
EIA/JESD Standard 51-2.
Per JEDEC JESD51-6 with the board horizontal.
Thermal resistance between the die and the printed circuit board in conformance with 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 in conformance with Psi-JT.
JMA
Thermal Characteristics
and Ψ
= Ambient Temperature, °C
= Package Thermal Resistance, Junction-to-Ambient, °C/W
= P
= I
= Power Dissipation on Input and Output Pins — User Determined
jt
parameters are simulated in conformance with EIA/JESD Standard 51-2 for natural convection.
I/O
INT
DD
< P
× IV
+ P
Characteristic
INT
I/O
DD
MCF5445x ColdFire
and can be ignored. An approximate relationship between P
, Watts - Chip Internal Power
K
jt
J
parameter, the device power dissipation, and the method described in
) in °C can be obtained from:
=
Table 6. Thermal Characteristics
P
JmA
D
T
J
×
P
and power dissipation specifications in the system design to prevent
(
Four layer board
Four layer board
=
D
T
T
A
=
®
A
×
(2s2p)
(2s2p)
-------------------------------- -
(
Microprocessor Data Sheet, Rev. 0
+
T
273°C
(
J
P
+
D
K
273°C
×
)
Θ
+
JMA
Q
)
JMA
)
Symbol
θ
θ
θ
θ
×
Ψ
JMA
T
JC
JA
JB
P
jt
j
2
D
256MAPBGA
29
25
2
105
18
10
1,5
1,2
1,2
3
4
D
and T
360PBGA
Freescale Semiconductor
J
24
21
2
105
15
11
(if P
1,5
1,2
1,2
3
4
I/O
is neglected) is:
°C / W
°C / W
°C / W
°C / W
°C / W
Unit
o
C
Eqn. 1
Eqn. 2
Eqn. 3