Fluke 5725A, Instruction Manual, Page: 92 / 196

5725A
Instruction Manual
4-34
latch up by eliminating positive feedback resulting from positive output voltages from
U100. Op amp U105 is simply a low-noise inverting amplifier that scales the sensor
output to 10 dB below the 5700A Oscillator output level. The output of the calibration
circuit, AC/AC, goes to the 5700A during calibration through the analog monitor
section.
Analog Monitor Section 4-56.
The 16-channel multiplexer, U151, takes a variety of inputs from all analog assemblies
and provides a means of switching them to either a comparator, U154A, or to the B-RCL
line via K152. During normal operation, the multiplexer output is routed exclusively to
the comparator. Calibration requires routing the multiplexer output to the B-RCL line,
which is routed back to the 5700A. The B-RCL line is measured by the precision adc
circuit on the 5700A DAC assembly. All inputs to the multiplexer are scaled so that
inputs are within its
±
15V power supply range. Table 4-4 shows the signal name of the
multiplexer input, its description, origin, and purpose.
The state of the multiplexer is controlled by the microprocessor via data latched into
U152.
Table 4-4. Signals Monitored by the Analog Monitor Section
STANDBY
VOLTAGE
LIMITS(1)
SIGNAL
NAME
PHYSICAL
PARAMETER
SOURCE PURPOSE
-0.125V +400V IM Supply Current Power Supply Monitoring
+0.125V -400V IM Supply Current Power Supply Monitoring
0.26V +400V M Supply Voltage Power Supply Monitoring
-0.26V -400V M Supply Voltage Power Supply Monitoring

VCOM System Supply Common Power Supply Monitoring

HVCOM M High Voltage Supply
Common Power Supply Monitoring
1.7V HVTEMP M Voltage Amp Heat Sink
Temp. High Voltage Amplifier Monitoring
2.0V ITEMP M Current Amp Heat Sink
Temp. Current Amplifier Monitoring
-2.2V ICOMPL M Current Output Stage
Drive Level Current Amplifier Monitoring

I CAL/I FB Shunt Voltage Current Amplifier Calibration, AC I
Operation

AC/AC Calibrator Output High Voltage Sense Calibration

HVSENSE Sense Amp Output High Voltage Sense Calibration

DAC OUT DAC Output High Voltage Sense Monitoring
0.08, 2.0V FAN M Fan is On or Off Power Supply Monitoring
Note 1: For single limit values, the limit is equal to, or smaller in magnitude to, the value shown.