Power Supply - IBM 5150 Hardware Reference Manual

Power
Supply
The system DC power supply is a 63.5 watt, 4 voltage level switching
regulator. It is integrated into the System Unit and supplies power for
the System Unit, its options, and the keyboard. The supply provides 7
amps of+5 Vdc, +5% 2 amps of
+
12Vdc, +5% 300 rna of -5Vdc,
~+IO%
and 250 rna of -12 Vdc, +10%. All power levels are regulated
with overvoltage and over current protection. The input is 120 Vac and
fused. DC over-load or over-voltage conditions exist, the supply will
automatically shut down until the condition is corrected. The supply is
designed for continuous operation at 63.5 watts.
The System Board takes approximately 3 amps of
+
5 V dc thus
allowing approximately 4 amps of 5 V dc for the adapters in the System
Expansion Slots. The + 12 V dc power level is designed to power the
two internal
5-1/4"
Diskette Drives and the system's dynamic
memory. It is assumed that only one drive motor is active at a time. The
- 5 V dc level is used for memory bias voltage and analog circuits in
the diskette adapter phase lock loop. The
+
12 V dc and -12 V dc are
used for powering the serial interface card EIA drivers and receivers
for the Asynchronous Communications Adapter. All four power levels
are bussed across the five System Expansion Slots and available
for option adapter.
~
The IBM Monochrome Display is self-powered. However, the high
resolution display receives its AC power from the System Unit power
system. It is switched on and off with the power switch, which saves a
wall outlet. The AC output for the display is a nonstandard connector,
so only the AC high resolution Display can use this AC port.
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