vsc8131 Vitesse Semiconductor Corp, vsc8131 Datasheet - Page 15

• Manufacturer Part Number: vsc8131
• Description: 2.488 Gbit/sec 32 1 Sonet/sdh Mux With Clock Generator
• Manufacturer: Vitesse Semiconductor Corp

VSC8131
Preliminary Datasheet
11/9/99
G52249-0, Rev. 3.0
Package Thermal Considerations
die to the exposed surface of the heat spreader. The thermal resistance is shown in the following table
Table 5: Thermal Resistance
Thermal Resistance with Airflow
thermal paths including through the leads in an environment where the leads are exposed. The temperature dif-
ference between the ambient airflow temperature and the case temperature should be the worst case power of
the device multiplied by the thermal resistance.
Table 6: Thermal Resistance with Airflow
Maximum Ambient Temperature without Heatsink
P
This package has been enhanced with a copper heat slug to provide a low thermal resistance path from the
Shown in the table below is the thermal resistance with airflow. This thermal resistance value reflects all the
The worst case ambient temperature without use of a heatsink is given by the equation:
where:
The results of this calculation are listed below:
A(MAX)
(MAX)
CA
C(MAX
Symbol
100 lfpm
200 lfpm
400 lfpm
600 lfpm
Airflow
Theta case to ambient at appropriate airflow
jc
ja
Power (2.15W for VSC8131)
)
Ambient Air temperature
Case temperature (85
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: [phone]
Thermal resistance from
junction to case.
Thermal resistance from
junction to ambient with no
airflow, including conduction
through the leads.
Description
VITESSE
VITESSE SEMICONDUCTOR CORPORATION
SEMICONDUCTOR CORPORATION
T
ca
o
A MAX
C for VSC8131)
19.8
16.7
14.6
13.0
(
o
C/W
)
=
T
C MAX
32:1 SONET/SDH Mux with Clock Generator
25.6
C/W
2.2
–
P
MAX
CA
2.488 Gbit/sec
Page 15