VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC8132

2.488Gb/s 1:32 SONET/SDH Demux

G52250-0, Rev 3.1

Page 13

12/7/00

© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com

Internet: www.vitesse.com

Package Thermal Considerations

The VSC8132 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 Table 4.

Table 4: Thermal Resistance

Thermal Resistance with Airflow

Thermal resistance with airflow is shown in Table 5. The thermal resistance value reflects all the thermal

paths including through the leads in an environment where the leads are exposed. The temperature difference

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

C(MAX)

Power (2.05W)

θ

CA

Theta case-to-ambient at appropriate airflow

Symbol

Description

°C/W

θ

JC

Thermal resistance from junction-to-case.

2.2

θ

JA

Thermal resistance from junction-to-ambient with no airflow, including

conduction through the leads.

26.8

Airflow

θ

100 lfpm

19.8

200 lfpm

16.7

400 lfpm

14.6

600 lfpm

13.0

T

AMAX

()

T

CMAX

()

P

–

MAX

=