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Chapter 7 Power and Signal Distribution
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
7-2
7.2.1
POWER SUPPLY ASSEMBLY
The power supply assembly is contained in a single unit that features a selectable input voltage:
90-132 VAC and 180-264 VAC. The power supply assembly provides +3.3 VDC, +5 VDC, -5
VDC, +12 VDC, and -12 VDC potentials for the system board, expansion board(s), and installed
drives. These voltages are controlled through the power button on the front panel of the system
unit. Pressing and releasing the power button results in system board logic asserting the PS On
signal, which activates the power supply assembly.
The power supply also produces an auxiliary voltage (+5 AUX). The +5 AUX voltage is used for
powering the power button and other logic required for wake-up operation and is produced as
long as the unit is plugged into a live AC outlet.
NOTE:
Minimum loading requirements for the power supply must be met at all times to
ensure normal operation and to meet specifications.
Table 7-1 shows the specifications for the power supply.
Table 7–1. Power Supply Assembly Specifications
Table 7-1.
Power Supply Assembly Specifications
(P/N 334112-xxx)
Parameter
Range/
Tolerance
Min. Current
Loading [1]
Max.
Current
Surge
Current [2]
Max.
Ripple
Input Line Voltage:
110 VAC Setting
220 VAC Setting
90 - 132 VAC
180-264 VAC
--
--
--
--
--
--
--
--
Line Frequency 47 - 63 Hz -- -- -- --
Steady State Input (VAC) Current: -- -- 5.50 A -- --
+3.3 VDC Output +/- 1% 1.40 A 10.0 A 10.0 A 50 mV
+5 VDC Output +/- 5 % 1.40 A 25.0 A 25.0 A 50 mV
-5 VDC Output +/- 10 % 0.00 A 0.15 A 0.15 A 100 mV
+5 AUX Output +/- 5 % 0.10 A 2.00 A 2.00 A 50 mV
+12 VDC Output +/- 5 % 0.07 A 4.50 A 7.00 A 120 mV
-12 VDC Output +/- 10 % 0.00 A 0.15 A 0.15 A 200 mV
NOTES:
[1] Minimum loading requirements must be met at all times to ensure normal operation
and specification compliance.
[2] Surge duration no longer than 10 seconds and +12 tolerance +/- 10%.
The power supply assembly contains a fan that can be shut down by the Fan Off signal, which is
asserted from the system board logic during sleep (suspend) states. The power supply can
override the Fan Off signal if the temperature in the power supply assembly is too high.