vsc8122 Vitesse Semiconductor Corp, vsc8122 Datasheet - Page 12

• Manufacturer Part Number: vsc8122
• Description: Multi-rate Sonet/sdh Clock And Data Recovery Ic
• Manufacturer: Vitesse Semiconductor Corp

Page 12
Multi-Rate SONET/SDH
Clock and Data Recovery IC
Package Thermal Considerations
die to the exposed surface of the heat spreader. The thermal resistance is shown in the following table:
Table 9: 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 10: 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 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:
θ
T
T
P
CA
A(MAX)
(MAX)
C(MAX)
100 lfpm
200 lfpm
400 lfpm
600 lfpm
Airflow
= Theta case to ambient at appropriate airflow
Symbol
θ-ca
θ-jc
= Power (1.2W for VSC8122)
= Ambient Air temperature
= Case temperature (85
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Thermal resistance from junction to case.
Thermal resistance from case to ambient with no airflow,
including conduction through the leads.
Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]
VITESSE
θ -ca (
SEMICONDUCTOR CORPORATION
o
T
C for VSC8122)
A(MAX)
25.8
23.0
19.3
17.0
o
C/W)
= T
Internet: www.vitesse.com
Description
C(MAX)
- P
(MAX)
θ
CA
o
31.5
C/W
1.5
VSC8122
Data Sheet
G52228-0, Rev 4.1
01/05/01