VSC7125 Datasheet, PDF (14/16 Pages) Vitesse Semiconductor Corporation – 1.0625 Gbits/sec Fibre Channel Transceiver

VITESSE
SEMICONDUCTOR CORPORATION
1.0625 Gbits/sec Fibre
Channel Transceiver
Data Sheet
VSC7125
Package Thermal Considerations
The VSC7125 is packaged in either a 10 mm PQFP or a 14 mm PQFP with internal heat spreaders. These
packages use industry-standard EIAJ footprints, but have been enhanced to improve thermal dissipation. The
construction of the packages is as shown in Figure 11.
Figure 11: Package Cross Section
Plastic Molding Compound
Aluminum Heat Spreader
Lead
Bond Wire
Epoxy
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
10.5
53
44
39
34
31
14mm Value
10
32
28
25
22
20
Units
o_C/W
o_C/W
o_C/W
o_C/W
o_C/W
o_C/W
The VSC7125 is designed to operate with a junction temperature up to 110^oC. The user must guarantee that
the temperature specification is not violated. With the Thermal Resistances shown above, the 10x10mm PQFP
can operate in still air ambient temperatures of 53^oC [53^oC=110^oC-0.9W*(10.5^oC/W+53^oC/W)] while the
14x14 PQFP can operate in still air ambient temperatures of 73^oC [73^oC=110^oC-0.9W*(10^oC/W+32^oC/W)]. If
the ambient air temperature exceeds these limits then some form of cooling through a heatsink or an increase in
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.
Page 14
© VITESSE SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: [phone]
G52121-0, Rev. 4.1
4/23/98