89ttm552 Integrated Device Technology, 89ttm552 Datasheet - Page 18

• Manufacturer Part Number: 89ttm552
• Description: Standalone 10g Simplex Traffic Manager
• Manufacturer: Integrated Device Technology

89TTM552 Thermal Considerations
89TTM552 Thermal Considerations
89TTM552 Thermal Considerations
89TTM552 Thermal Considerations
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.
IDT 89TTM552
This section describes the temperature and heat sink calculations for flip-chip BGA devices.
The thermal circuit is as shown below.
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
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
Symbol
J
Ø
Ø
Ø
JC
JA
JB
- W x
Ø
Thermal resistance, junction to ambient (no heat sink)
Estimated thermal resistance, junction to board
Thermal resistance, junction to case
Ø
----------------------
JB
JB
x (
+
Ø
Ø
JC
JC
+
+
Ø
Ø
Ø
JB
CA
CA
Total Power
= W
and
)
Device
Ø
JC
Parameter
Table 25 89TTM552 Thermal Characteristics
numbers. The
T
Figure 4 89TTM552 Thermal Circuit
J
Ø
Ø
JC
JB
Ø
18 of 37
CA
W1
W2 (dissipated through board)
number comes from the heat sink manufacturer and depends on type of heat
Ø
CA
Value Units
T
T
A
A
0.19
9.0
5.5
4.5
2.2
°C / W
°C / W
°C / W
°C / W
°C / W
Conditions
A
200 FPM.
500 FPM
) that can be tolerated based
Still air.
April 7, 2005