VSC7135 Datasheet, PDF (14/16 Pages) Vitesse Semiconductor Corporation – 1.25Gbits/sec Gigabit Ethernet Transceiver

VITESSE
SEMICONDUCTOR CORPORATION
1.25Gbits/sec
Gigabit Ethernet Transceiver
Data Sheet
VSC7135
Package Thermal Considerations
The VSC7135 is packaged in a 14 mm conventional PQFP with an internal heat spreader. This package use
an industry-standard EIAJ footprint, but have been enhanced to improve thermal dissipation. The construction
of the packages are as shown in Figure 12.
Figure 10: Package Cross Section - 14 mm package
Plastic Molding Compound
Copper Heat Spreader
Lead
Bond Wire
Die
Table 5: 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.
Thermal resistance from case to ambient with 100 LFM airflow
Thermal resistance from case to ambient with200 LFM airflow
Thermal resistance from case to ambient with 400 LFM airflow
Thermal resistance from case to ambient with 600 LFM airflow
10mm Value 14mm Value
10.0
9.5
50.8
29
41.2
26.1
36.9
23.8
31.8
20.5
27.8
17.9
Units
o_C/W
o_C/W
o_C/W
o_C/W
o_C/W
o_C/W
The VSC7135 is designed to operate with a junction temperature up to 105^oC. The user must guarantee that
the temperature specification is not violated. With the Thermal Resistances shown above, the 10x10 PQFP can
operate in still air ambient temperatures of 55^oC [55^oC=110^oC-0.9W*(10^oC/W+50.8^oC/W)] while the 14x14
PQFP can operate in still air ambient temperatures of 75^oC [75^oC=110^oC-0.9W*(9.5^oC/W+29^oC/W)]. If the
ambient air temperature exceeds these limits then some form of cooling through a heatsink or an increase in air-
flow 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.
Page 14
© VITESSE SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: [phone]
G52146-0, Rev. 4.0
5/28/98