89ttm553 Integrated Device Technology, 89ttm553 Datasheet - Page 14

• Manufacturer Part Number: 89ttm553
• Description: Traffic Manager Co-processing Engine
• Manufacturer: Integrated Device Technology

to air. The device specifications provide
sink (area, height, fin type, etc.) and the airflow across the heat sink. The device specifications also provide the maximum operating junction tempera-
ture (T
under any operating condition. One method of accomplishing this is to calculate the maximum ambient temperature (T
on the above device parameters. The formula is shown below.
that meets the maximum ambient temperature requirements of their system.
thermal resistance of the package (junction to case + case to ambient) and is mainly specified as a reference parameter. (This is when a heat sink is
not present and the top surface of the package is essentially acting as the heat sink). However, in devices that have high power dissipation, heat sink
usage is highly desirable. Consequently, system designers may have limited use for this parameter.
IDT 89TTM553
For flip-chip BGA devices, there are two paths for heat dissipation: one through the package balls to the board and other through the package case
The following graph depicts the ambient temperature (T
For system designers, specification of the maximum device junction temperature (operating) is critical, since it allows them to select a heat sink
The other parameter that is device package-specific is
J
T
) that will not degrade the device reliability. The system designer should ensure that the device maximum junction temperature is not exceeded
A
= T
J
- W x
Ø
Ø
-----------------------
JB
JB
x (
+
Ø
Ø
JC
JC
+
+
Ø
90.0
80.0
70.0
60.0
50.0
40.0
30.0
Ø
Ø
JB
CA
CA
and
)
1.0
81.0
Ø
JC
Figure 3 89TTM553 Ambient Temperature Curve
numbers. The
2.0
79.7
Ø
A
) versus
JA
Ambient Temp. vs Ø
, without a heat sink, and is specified for various air-flow conditions. This is the intrinsic
3.0
78.8
Ø
Ø
14 of 30
CA
CA.
Ø
number comes from the heat sink manufacturer and depends on type of heat
4.0
CA
78.2
o
C/W
5.0
77.7
CA
6.0
77.2
7.0
76.9
8.0
76.6
A
) that can be tolerated based
March 3, 2005