Compaq Deskpro 4000 - 7.2.1 POWER SUPPLY ASSEMBLY

Chapter 7 Power and Signal Distribution
Compaq Deskpro 4000 and 6000 Personal Computers
featuring the Pentium II Processor
First Edition - October 1997
7-2
7.2.1
POWER SUPPLY ASSEMBLY
The power supply assembly is contained in a single unit that features a selectable input voltage:
90-135 VAC and 180-265 VAC. The assembly provides power for the system board, expansion
board(s), and installed drives. A fault-detection circuit automatically shuts down the power
supply when certain faults are detected. Faults that can trigger the protection circuitry include:
♦ Overvoltage - The +5 VDC output will activate the overvoltage crowbar circuit that triggers
the protection circuit when the output exceeds +5.60 VDC to +6.80 VDC. The +3.5 VDC
output will activate the overvoltage crowbar circuit when the output is sensed to be in the
+3.7 VDC to +5.0 VDC range.
♦ Short Circuit - The protection circuit triggers if any power supply output is shorted to
ground or to another output. This function reduces shock or fire hazard
All voltages except the +5AUX are controlled by the PS On signal. The +5AUX signal, produced
by the power supply assembly as long as AC is supplied, is used by the power control logic and
the network interface controller.
Table 7-1 shows the specifications for the power supply.
Table 7–1. Power Supply Assembly Specifications
Table 7-1.
Power Supply Assembly Specifications
Parameter 200 Watt Supply 280 Watt Supply
Input Line Voltage Range
110 VAC (North American) Setting:
220 VAC Setting:
90 - 132 VAC
180-264 VAC
90 - 132 VAC
180-264 VAC
Line Frequency: 47 - 63 Hz 47 - 63 Hz
Minimum Loading Current
+3.5 VDC:
+5 VDC:
-5 VDC:
+5 AUX:
+12 VDC:
-12 VDC:
0.75 A
0.75 A
0.00 A
0.10 A
0.00 A
0.00 A
0.75 A
0.75 A
0.00 A
0.10 A
0.00 A
0.00 A
Maximum Output Current:
+3.5 VDC (+/-1%):
+5 VDC (+/-5 %):
-5 VDC (+/-10 %):
+5 AUX (+/-5 %):
+12 VDC (+/-5 %):
-12 VDC (+/-10 %):
10.0 A
25.0 A
.15 A
1.2 A
4.5 A
0.15 A
10.0 A
32.0 A
.15 A
1.2 A
7.0 A
0.15 A
Combined Max. Output Power of +3.5 & +5 VDC: 135 watts 170 watts
The system fan is driven by the power supply assembly and adjusted in a linear fashion (5.5-13.6
VDC). The power control logic also has control over the fan through temperature sensing logic
(described in chapter 4) that controls the FAN OFF signal to the power supply assembly. A
temperature sensor within the power supply assembly can override the condition of the FAN OFF
signal if the ambient temperature of the power supply is too high.