32 x 32 1.5 GBIT/S DIFFERENTIAL CROSSPOINT SWITCH
S2025
THERMAL MANAGEMENT GUIDELINES
Because of the relatively high power dissipation of the
S2025 device, thermal management is a key design
consideration. The junction temperature (Tj) of the
device must not exceed 150°C for it to operate within its
specifications. There are a number of ways to imple-
mentthermalmanagement,dependinguponthesystem
requirements and applications. AMCC is offering the
following two methods as guidelines to ensure proper
operation of the S2025.
2. Conduction—Liquid Cooling Methods
Passive cooling schemes, such as Aavid
Engineering’s Oasis technology may also be used
to ensure low junction temperature. Oasis uses
Flourinert, aliquidthatboilsaround57°C, totransfer
heat from the hot device to a condenser, where the
vaporizedFlourinertiscooled,becomesliquidagain,
and returns to the hot device. The S2025 case
temperaturewouldnotexceed57°C, aslongasthe
cooling system is functioning properly. In such
case, using the following equation, one could calcu-
latethemaximumanticipatedTj tobearound85°C.
1. Convection—Heat Sink with Forced Air Flow
AMCC offers the standard heat sink 45–17 for
impingement cooling (air flow forced directly to the
face of the heat sink). This method is similar to the
fan/heat-sink devices used on new, high-perfor-
mance, and high-power microprocessors. The
dimensions of the heat sink are given in Figure 6.
Tj = Tc + (Pd x 2)
(Tc is the case temperature in °C, and
Pd is the dissipated power in Watts.)
For more information on Oasis technology, please
contact:
Considering the junction-to-case, and case-to-
ambient thermal resistivities, one can estimate the
amount of required air flow and the maximum
ambient temperature (Ta) in order to keep the Tj
below the critical limit of 150°C. Table 4 lists these
values for 45-17 and 45-24 heat sinks when Tj =
150°C.
Aavid Engineering Incorporated
Oasis Products Group
One Kool Path/P.O. Box 400
Laconia, NH 03247-0400
Tel: 603/528-3400
FAX: 603/528-1478
Table 4. Maximum Ambient Temperatures
Ta ˚ C (max)
Air Flow (LFPM)
(H/S 45-17)
30
50
60
70
200
400
600
800
12
June 24, 1999 / Revision B
AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
