ARMY TM 5-6675-308-34
MARINE CORPS TM 08837A-34/2
switching regulator requires + 15 and -- 15V for its
(6) 15 V precision supply. The 15V precision
operational amplifiers and a 40-kHz square wave signal
supply is located on the 5V power supply circuit card
for its pulse width modulation section. The normal
assembly. The --15V precision supply is a linear series-
pass type regulator with an input voltage of 19V from
control signal for the + 5V switching regulator is regu-
lator-on. When any one of the computer power supplies
the DC-to-DC converter and an output voltage of
five output voltages exceeds its maximum allowable
15V with load variations of 0.1 to 1.2 amps.
limit, or when more than 8 amps is drawn from the O to
(7) Control and monitor section. The control and
+ 5V switching regulator, the crowbar signal (CB)
monitor section consists of MOS logic and voltage
goes to O volts and initiates an emergency power supply
comparators and is located on the 15V power supply
shutdown. This emergency shutdown is accomplished
circuit card assembly. The monitor portion consists of
by firing a silicon controlled rectifier (SCR) which shorts
voltage comparators and their associated precision re-
the output of the + 5V switching regulator and simulta-
sistor dividers, All the computer power supply output
neously causes the regulator-on signal to go low.
voltages are compared in the monitor circuit to sepa-
rate high and low voltage references. If any output
(2) 0 to + 5V switching regulator. The O to + 5V
voltage is below the low reference, the low voltage
switching regulator is located on the 15V power supply
(LV) signal goes high. If any output voltage goes above
circuit card assembly. This regulator is commanded by
the high reference, the crowbar (CB) signal goes high.
an analog reference signal (V lamp ref) which originates
When either of these signals goes high, the computer
in the computer. The output of the regulator follows
power supply will shut down. The control portion
the V lamp reference signal. The regulator supplies O to
contains logic that controls the tumon and turnoff of
+ 5V with input variations of +20 to + 30V and load
the computer power supply. This circuitry initiates
variations of 0 to 5 amps. Operation of the 0 to + 5V
tumon when the + 24V input from the power supply
switching regulator is similar to the + 5V switching
goes above + 21V. For the first second after initial
regulator. In addition to current limiting at 8 amps, a
tumon, a high signal (PS POR) is sent to the computer
power supply shutdown signal (VLOC) is sent to the
for initialization of the computer and its memory. The
control and monitor circuitry when the load current
+15 and 15V precision supplies are enabled first,
exceeds 8 amps. Asterisk denotes negative logic. The O
When the ouput of these supplies reach greater than
to + 5V switching regulator responds to the regulator-
+ 10V, the three switching regulators are turned on.
on and CB signals in the same manner as the + 5V
During the time the PS POR is high, only an overvolt-
switching regulator.
age (CBO) or the computer command (PS 0FF) can
shut down the computer power supply. During normal
(3) +25 V switching regulator. The + 15V switch-
ing regulator is located on the 15V power supply
operation, a low voltage (LV), overvoltage (CB), or the
circuit card assembly. This regulator supplies + 15V
computer command (PS Off can turn off the computer
power supply. Anytime the CBO or LV signals initiate
with input variations of +20 to + 30V and load varia-
the shutdown, a built-in-test magnetic latching indicator
tions of 1 to 6 amps. The operation of the + 15V
will be set by the flag set' control signal. The power for
switching regulator is similar to the + 5V switching
regulator.
the monitor and control section is supplied by an
auxiliary + 5V regulator that operates directly from the
(4) DC-to-dc converter. The dc-to-dc converter is
+ 24V input power. In addition to the control and
located on the 5V power supply circuit card assembly.
voltage monitoring functions, this section also contains
The converter receives its input from a + 12V supply at
an oscillator that generates a + 30V peak-to-peak, 40-
turn-on and then from the + 15V switching regulator
kHz square wave.
during normal operation. The converter switches at
approximately 28 kHz and generates square waves of O
to + 20V on a secondary winding of the converter
supply assembly converts +20 to + 30V vehicle or
transformer. These square waves are rectified and filt-
PADS battery power to the following outputs:
ered and supply +19 and 19V to the 15V precision
supplies. The converter transformer has two additional
115V RMS, 0 phase, 400 Hz, square wave, unregulated
secondary windings. The square waves on these wind-
115V RMS, 90 phase, 400 Hz, sine wave, regulated
ings are again rectified and filtered, producing a floating
26V RMS, 90 phase, 400 Hz, sine wave, regulated
+3V which is used as a boost voltage for the two
switching regulators.
28V, regulated
(5) +15 V precision supply. The + 15V precision
+ 28V, battery charge, regulated
supply is located on the 5V- power supply circuit card
assembly. The + 15V precision supply is a linear series-
functional Mock diagram. The circuit assemblies within
pass type regulator with an input voltage of + 19V
the power supply assembly are as follows:
from the DC-to-DC converter and an output voltage of
+ 15V with load variations of 40 to 260 mA.
RFI filters
2-9
Previous Page
