VSC8140QR VITESSE [Vitesse Semiconductor Corporation], VSC8140QR Datasheet - Page 32

• Manufacturer Part Number: VSC8140QR
• Description: 2.48832Gb/s 16:1 SONET/SDH Transceiver with Integrated Clock Generator
• Manufacturer: VITESSE [Vitesse Semiconductor Corporation]

Transceiver with Integrated Clock Generator
2.48832Gb/s 16:1 SONET/SDH
Page 32
Package Thermal Considerations
die to the exposed surface of the heat spreader. The thermal resistance is shown in the following table:
Table 6: 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 7: Thermal Resistance with Airflow
Maximum Ambient Temperature without Heatsink
Symbol
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:
CA
A(MAX)
(MAX)
C(MAX
ca
jc
100 lfpm
200 lfpm
400 lfpm
Airflow
Theta case to ambient at appropriate airflow
Power (2.75 W for VSC8140)
)
Ambient Air temperature
Case temperature (110
Thermal resistance from junction to case.
Thermal resistance from case to ambient with no airflow,
including conduction through the leads.
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: [phone]
VITESSE
SEMICONDUCTOR CORPORATION
VITESSE SEMICONDUCTOR CORPORATION
T
o
A MAX
C for VSC8140)
Description
ca
(
o
C/W
18
17
16
=
) (BGA)
T
C MAX
–
P
MAX
CA
C/W - (BGA)
18.5
ca
2.2
(
o
C/W
21
18
16
) (PQFP)
C/W (PQFP)
VSC8140
Data Sheet
G52251-0, Rev. 4.0
1.34
25.0
9/6/00