VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Datasheet

VSC8166

2.488 Gbit/sec

1:16 SONET/SDH Demux with Clock Recovery

Page 14

© VITESSE SEMICONDUCTOR CORPORATION

G52252-0, Rev 3.0

741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896

11/9/99

Package hermal Considerations

This package has been enhanced with a copper heat slug to provide a low thermal resistance path from the

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

Shown in the table below is the thermal resistance with airflow. This thermal resistance value reflects all the

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

The worst case ambient temperature without use of a heatsink is given by the equation:

where:

Τ

Τ

θ

The results of this calculation are listed below:

Symbol

Description

°C/W

Thermal resistance from

junction to case.

2.2

Thermal resistance from

junction to ambient with no

airflow, including conduction

through the leads.

23.9

Airflow

θ

100 lfpm

19.8

200 lfpm

16.7

400 lfpm

14.6

600 lfpm

13.0

T

AMAX

()

T

CMAX

()

P

–

MAX

=