VSC8163QR VITESSE [Vitesse Semiconductor Corporation], VSC8163QR Datasheet - Page 18

• Manufacturer Part Number: VSC8163QR
• Description: OC-48 16:1 SONET/SDH MUX with Clock Generator
• Manufacturer: VITESSE [Vitesse Semiconductor Corporation]

Page 18
OC-48 16:1 SONET/SDH
MUX with Clock Generator
Thermal Considerations
die to the exposed surface of the heat spreader. The thermal resistance is shown in the following table
Table 4: 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 5: Thermal Resistance with Airflow
Maximum Ambient Temperature without Heatsink
This package has been enhanced with a copper heat slug to provide a low thermal resistance path from the
Shown in the Table 5 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:
P
CA
A(MAX)
(MAX)
C(MAX)
100 lfpm
200 lfpm
400 lfpm
600 lfpm
Airflow
Symbol
CA
JC
Theta case-to-ambient at appropriate airflow
Ambient Air temperature
Case temperature (85
Power (1.7W for VSC8163)
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]
Thermal resistance from junction-to-case.
Thermal resistance from case-to-ambient with no
airflow, including conduction through the leads.
VITESSE
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SEMICONDUCTOR CORPORATION
14.5
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Internet: www.vitesse.com
Description
T
C MAX
–
P
MAX CA
Preliminary Data Sheet
1.34
25.0
C/W
VSC8163
G52216-0, Rev 3.3
01/05/00