VSC7140 Datasheet, PDF (11/12 Pages) Vitesse Semiconductor Corporation – 1.0625 Gb/s Fibre Channel Dual Repeater / Hub Node

Data Sheet
VSC7140
VITESSE
SEMICONDUCTOR CORPORATION
1.0625 Gb/s Fibre Channel
Dual Repeater / Hub Node
Package Thermal Characteristics
The VSC7140 is packaged into a thermally-enhanced plastic quad flatpack. This package adheres to the
industry-standard EIAJ footprint for a 10x10mm body but has been enhanced to improve thermal dissipation
with the inclusion of an exposed copper heat spreader. The package construction is as shown in Figure 6.
Figure 6: Package Cross Section
Copper Heat Spreader
Insulator
Lead
Wire Bond
Die
Plastic Molding Compound
The thermal resistance for the VSC7140 package is improved through low thermal resistance paths from
the die to the exposed surface of the heat spreader and from the die to the leadframe through the heat spreader
overlap of the leadframe.
Table 3: 52 PQFP Thermal Resistance
Symbol
θ_jc
θ_ca
θ_ca-100
θ_ca-200
θ_ca-400
θ_ca-600
Description
Thermal resistance from junction to case
Thermal resistance from case to ambient in still air including conduction through
the leads for a non-thermally saturated board.
Thermal resistance from case to ambient in 100 LFPM air.
Thermal resistance from case to ambient in 200 LFPM air.
Thermal resistance from case to ambient in 400 LFPM air.
Thermal resistance from case to ambient in 600 LFPM air.
Value
2.5
37.0
31.0
28.0
24.0
22.0
Units
o_C/W
o_C/W
o_C/W
o_C/W
o_C/W
o_C/W
The user must ensure that the maximum case temperature specification (95^o C) is not exceeded. Given the
thermal resistance of the package in still air, the user may operate the VSC7140 in still air if the ambient tem-
perature does not exceed 32^o C (95^o C - 1.7W * 37^o C/W = 32^o C). If operation above this ambient temperature
is required, an appropriate heatsink must be used with the part or adequate airflow must be provided.
Moisture Sensitivity Level
This device is rated with a moisture sensitivity level 3 rating. Refer to Application Note AN-20 for appro-
priate handling procedures.
G52180-0, Rev 4.0
10/23/00
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]
Internet: www.vitesse.com
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