Datasheet

MPC8260A PowerQUICC™ II Integrated Communications Processor Hardware Specifications, Rev. 2.0
12 Freescale Semiconductor
Electrical and Thermal Characteristics
2.2 Thermal Characteristics
Table 4 describes thermal characteristics.
2.3 Power Considerations
The average chip-junction temperature, T
J
, in °C can be obtained from the following:
T
J
= T
A
+ (P
D
x
θ
JA
) (1)
where
T
A
= ambient temperature °C
θ
JA
= package thermal resistance, junction to ambient, °C/W
P
D
= P
INT
+ P
I/O
P
INT
= I
DD
x V
DD
Watts (chip internal power)
P
I/O
= power dissipation on input and output pins (determined by user)
For most applications P
I/O
< 0.3 x P
INT
. If P
I/O
is neglected, an approximate relationship between P
D
and
T
J
is the following:
P
D
= K/(T
J
+ 273° C) (2)
Solving equations (1) and (2) for K gives:
K = P
D
x (T
A
+ 273° C) +
θ
JA
x P
D
2
(3)
2
The leakage current is measured for nominal VDD, VCCSYN, and VDD.
3
MPC8265 and MPC8266 only.
Table 4. Thermal Characteristics for 480 TBGA Package
Characteristics Symbol Value Unit Air Flow
Junction to ambient
θ
JA
13
1
1
Assumes a single layer board with no thermal vias
°C/W
NC
2
2
Natural convection
10
1
1 m/s
11
3
3
Assumes a four layer board
NC
8
3
1 m/s
Junction to board
4
4
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.
θ
JB
4 °C/W —
Junction to case
5
5
Thermal resistance between the die and the case top surface as measured by the cold plate method (MIL
SPEC-883 Method 1012.1).
θ
JC
1.1 °C/W —