Digital Equipment AXPpci 33, Руководство по конструкции

Страница: 53 / 98

Environmental Data
Table 3–11 DECchip 21068A (100 MHz) Cooling Using Low-Profile Heatsink
Air
Velocity
LFM
AXPpci 33
CPU Power
T c
Max Theta jc Theta ja Theta ca
Maximum
Ambient
Temperature Notes
100 10W 93°C 0.70°C/W 7.25°C/W 6.55°C/W 28°C 1
200 10W 93°C 0.70°C/W 5.70°C/W 5.00°C/W 43°C 1
400 10W 93°C 0.70°C/W 3.80°C/W 3.10°C/W 62°C 1, 2
600 10W 93°C 0.70°C/W 2.80°C/W 2.10°C/W 72°C 1, 2
800 10W 93°C 0.70°C/W 2.35°C/W 1.65°C/W 77°C 1, 2
1,000 10W 93°C 0.70°C/W 2.10°C/W 1.40°C/W 79°C 1, 2
Using part number 12–35739–18 low-profile heatsink.
Notes:
1 If the recommended thermal pad (thermal interface between the 21068A and heatsink) is not used, the Theta jc
and Theta ja values will increase by 0.45°C/W. The end result will be a decrease in maximum allowable ambient
temperature by 5°C.
2 Operation above 40°C ambient temperature will require further thermal analysis by the system integrator. This
ensures that maximum operating temperatures are not exceeded for any other device including storage devices,
power supplies, PCI or ISA option modules, or other chips on the MLB.
Table 3–12 DECchip 21068A (100 MHz) Cooling Using High-Profile Heatsink
Air
Velocity
LFM
AXPpci 33
CPU Power
T c
Max Theta jc Theta ja Theta ca
Maximum
Ambient
Temperature Notes
0 10W 93°C 0.70°C/W 4.60°C/W 3.90°C/W 44°C 1
100 10W 93°C 0.70°C/W 3.50°C/W 2.80°C/W 65°C 1, 2
200 10W 93°C 0.70°C/W 2.55°C/W 1.85°C/W 75°C 1, 2
400 10W 93°C 0.70°C/W 2.00°C/W 1.30°C/W 80°C 1, 2
600 10W 93°C 0.70°C/W 1.80°C/W 1.10°C/W 82°C 1, 2
800 10W 93°C 0.70°C/W 1.60°C/W 0.90°C/W 84°C 1, 2
1,000 10W 93°C 0.70°C/W 1.50°C/W 0.80°C/W 85°C 1, 2
Using part number 12–35739–22 high-profile heatsink.
Notes:
1 If the recommended thermal pad (thermal interface between the 21068A and heatsink) is not used, the Theta jc
and Theta ja values will increase by 0.45°C/W. The end result will be a decrease in maximum allowable ambient
temperature by 5°C.
2 Operation above 40°C ambient temperature will require further thermal analysis by the system integrator. This
ensures that maximum operating temperatures are not exceeded for any other device including storage devices,
power supplies, PCI or ISA option modules, or other chips on the MLB.
3–7