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Intel® i960® RM/RN I/O Processor
®
Intel
80960RM/RN Processor 5 V and 3.3 V Design Considerations
9.2
Choosing a Power Source
The primary concern that must be addressed when selecting a power source is the maximum load
current requirement. The processor power supply must maintain correct voltage regulation at a
current of 5.0 A for the
Two options for supplying 3.3 V to the processor are:
•
Add a 3.3 V tap to the primary system power supply
•
Use on-board secondary regulation to derive 3.3 V from the 5 V system power supply
For on-board secondary regulation, a linear voltage regulator performs adequately for most designs
as shown in
Figure 9-18. Power Supply Circuit
+5V
If low heat or power dissipation is a design goal, then the higher complexity and cost of a switching
regulator may be warranted. Switching regulators offer better efficiency, thereby lowering
regulator power consumption and heat.
Figure 9-19
3.3 V "island."
Figure 9-19. Recommended Power Supply Connection Layout
3.3V Supply Using Linear Regulator
36
RM/RN I/O
processor.
Figure
9-18.
V
Linear
IN
Regulator
µ
10
F
shows recommended layouts for power supply or linear regulator connection to the
3.3V Regulator (upright) and Heatsink
V
3.3V
OUT
µ
10
F
*
Use a wide trace to power supply connector
3.3V Supply Using System Power Supply
Intel®
80960RM/RN
I/O Processor
100 MHz / 3.3 V
V
CC
Design Guide
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