Filter
Top Products
Chapter 7 Power and Signal Distribution
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
7-6
7.3.2 LOW VOLTAGE DISTRIBUTION
Voltages less than 3.3 VDC and processor core voltage are produced through regulator circuitry
on the system board.
Figure 7–3.
Low Voltage Supply, Block Diagram
The VccP regulator produces the VccP (processor core) voltage according to the state of the
VID4..0 signals from the processor. This allows automatic selection of the proper core voltage
depending on the installed processor component. The possible voltages available are listed as
follows:
VID4..0 VccP VID4..0 VccP VID4..0 VccP
10000 3.5 VDC 11011 2.4 VDC 00111 1.70 VDC
10001 3.4 VDC 11100 2.3 VDC 01000 1.65 VDC
10010 3.3 VDC 11101 2.2 VDC 01001 1.60 VDC
10011 3.2 VDC 11110 2.1 VDC 01010 1.55 VDC
10100 3.1 VDC 00000 2.05 VDC 01011 1.50 VDC
10101 3.0 VDC 00001 2.00 VDC 01100 1.45 VDC
10110 2.9 VDC 00010 1.95 VDC 01101 1.40 VDC
10111 2.8 VDC 00011 1.90 VDC 01110 1.35 VDC
11000 2.7 VDC 00100 1.85 VDC 01111 1.30 VDC
11001 2.6 VDC 00101 1.80 VDC 11111 CPU not installed
11010 2.5 VDC 00110 1.75 VDC
VccP (see text)
Regulator
Circuit
+12 VDC
VID0
Processor
VID1
VID2
VID3
+5 AUX
VTT
(
+1.5 VDC
)
Regulator
Circuit
Power Supply
Power Button and
Wake Up Logic
+5 VDC
VID4
+5 VDC
LM317
Regulator
Circuit
+3.3 VDC
2.5 VDC
LM317
Regulator
Circuit
+3 AUX
Pull-Up Logic
Processor