Digital Equipment AXPpci 33, Design Manual

Page: 55 / 98

Environmental Data
• If the custom heatsink footprint is larger than the DECchip 21066
PGA chip, the retaining clip may not fit.
3.2 DC Power Inputs
This section describes the DECchip 21066 power requirements, power
sequencing, and signals.
3.2.1 System Power Requirements
Tables 3–14 through 3–17 list the power requirements for the MLB
DECchip 21066 processor. Not included in these figures are any SIMMs,
cache, option modules, or fan. The +3.3 V used by the Alpha processor is
derived from the +5 V with an onboard regulator/sequencer.
Table 3–14 System DC Power Requirements (Using 21066 at 166 MHz)
Nominal
Input Typical Load
Current Maximum Load
Current Required
Regulation
+5 V 8.5 A 11 A ±5%
+12 V — 25 mA ±5%
-12 V — 23 mA ±10%
Table 3–15 System DC Power Requirements (Using 21066A at 233 MHz)
Nominal
Input Typical Load
Current Maximum Load
Current Required
Regulation
+5 V 8.5 A 13 A ±5%
+12 V — 25 mA ±5%
-12 V — 23 mA ±10%
Table 3–16 System DC Power Requirements (Using 21068 at 66MHz)
Nominal
Input Typical Load
Current Maximum Load
Current Required
Regulation
+5 V 6.0 A 7.3 A ±5%
+12 V — 25 mA ±5%
-12 V — 23 mA ±10%
Table 3–17 System DC Power Requirements (Using 21068A at 100 MHz)
Nominal
Input Typical Load
Current Maximum Load
Current Required
Regulation
+5 V 6.5 A 8 A ±5%
+12 V — 25 mA ±5%
3–9