Low Voltage Distribution; Figure 7-3. Low Voltage Supply - Compaq EN Series Technical Reference Manual

Chapter 7 Power and Signal Distribution
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.
Power Supply
Processor
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
10000 3.5 VDC
10001 3.4 VDC
10010 3.3 VDC
10011 3.2 VDC
10100 3.1 VDC
10101 3.0 VDC
10110 2.9 VDC
10111 2.8 VDC
11000 2.7 VDC
11001 2.6 VDC
11010 2.5 VDC
7-6 Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
LM317
+5 AUX
Regulator
Circuit
LM317
+5 VDC
Regulator
Circuit
+3.3 VDC
Regulator
Circuit
+5 VDC
+12 VDC
VID0
Regulator
VID1
Circuit
VID2
VID3
VID4
VID4..0 VccP
11011 2.4 VDC
11100 2.3 VDC
11101 2.2 VDC
11110 2.1 VDC
00000 2.05 VDC
00001 2.00 VDC
00010 1.95 VDC
00011 1.90 VDC
00100 1.85 VDC
00101 1.80 VDC
00110 1.75 VDC
Third Edition - September 1998
+3 AUX
2.5 VDC
VTT (+1.5 VDC)
VccP (see text)
VID4..0 VccP
00111 1.70 VDC
01000 1.65 VDC
01001 1.60 VDC
01010 1.55 VDC
01011 1.50 VDC
01100 1.45 VDC
01101 1.40 VDC
01110 1.35 VDC
01111 1.30 VDC
11111 CPU not installed
Power Button and
Wake Up Logic
Pull-Up Logic
Processor