
5725A
Instruction Manual
4-22
(ICAL, TP208) with the same amplitude and polarity as the current amplifier input voltage.
The calibration amplifier output is measured by circuitry within the 5700A during
calibration of the 5725A current amplifier. The calibration amplifier output is fed back
to the 5700A Oscillator during ac current operation.
The feedback signal from the precision shunt is applied to both the inner and outer loop
error amplifiers (ISENSE HI, ISENSE LO , pages 1 and 2). The error amplifier section
drives the output stage (TP204) so that the voltage across R272 is one-tenth of the
Current Amplifier input voltage (VINI). Thus, the Current Amplifier is a
transconductance amplifier: output current is proportional to input voltage. This
transconductance is -5A/V.
Output Stage Section
4-36.
Refer to page 1 of the Current Amplifier schematic. Components U203, R203, R204, and
R209 convert the bipolar ground-referenced output signal from the error amplifier
section into two unipolar supply-referenced waveforms at the inputs to U204A and
U204B. IC U203 also isolates the output stage, which is referenced to a floating common
(ICOM), from the rest of the circuitry, which is referenced to circuit common (VCOM).
The operation of the positive and negative output halves are similar. Only the positive
output section is described below.
In response to a positive polarity error amplifier output (TP204), the current through
R209 increases. This same current flows into pin 2 of U203, causing the voltage drop
across R203 to increase. The voltage across R203 is applied to the positive input of
U204A. U204A drives Q203, Q205, and Q207 until the voltage at the emitter of Q207 is
identical to the voltage at the non-inverting input of U204A. Test point TP204 is a test
input for the output stage when in standby mode. The resulting output stage current can
be monitored at TP208 with a scaling of 200 mV/A.
The quiescent operating point of the output devices is fixed by the bias current of U203
and current source CR205 at about 1A. There is no output stage bias adjustment.
Capacitor C235 and resistors R256 through R260 provide a tertiary feedback path that
guarantees stability when the 5725A is driving the specified inductive loads.
Monitor Section
4-37.
Refer to page 1 of the Current Amplifier schematic. Components U211C and D, U210C,
RT203, CR207, and associated resistors and capacitors make up the temperature-
monitoring circuit. Heat sink temperatures above approximately 85
°
C signal the
ITEMPM fault condition.
Components U207, R280 through 284, and C234 generate a negative voltage at TP207
(DRIVE MONITOR) that remains less than 3.1V in magnitude when the output
compliance voltage is within the linear operating range of the output stage. The output
compliance voltage is not measured by the drive monitor circuit; an overcompliance
condition is inferred from excessive error amplifier output.
Summary of Contents for 5725A
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Page 62: ...5725A Instruction Manual 4 4 Figure 4 1 5725A Overall Block Diagram...
Page 78: ...5725A Instruction Manual 4 20 aq20f eps Figure 4 3 Current Amplifier Assembly Block Diagram...
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Page 132: ...5725A Instruction Manual 8 6 aq24f tif Figure 8 1 Final Assembly...
Page 133: ...List of Replaceable Parts 8 8 7 aq25f tif Figure 8 1 Final Assembly cont...
Page 134: ...5725A Instruction Manual 8 8 aq26f tif Figure 8 1 Final Assembly cont...
Page 135: ...List of Replaceable Parts 8 8 9 aq27f tif Figure 8 1 Final Assembly cont...
Page 136: ...5725A Instruction Manual 8 10 aq28f tif Figure 8 1 Final Assembly cont...
Page 137: ...List of Replaceable Parts 8 8 11 aq29f tif Figure 8 1 Final Assembly cont...
Page 138: ...5725A Instruction Manual 8 12 aq30f tif Figure 8 1 Final Assembly cont...
Page 139: ...List of Replaceable Parts 8 8 13 aq31f tif Figure 8 1 Final Assembly cont...
Page 141: ...List of Replaceable Parts 8 8 15 5725A 1611 aq36f eps Figure 8 2 A1 Interconnect PCA...
Page 145: ...List of Replaceable Parts 8 8 19 5725A 1650 aq37f eps Figure 8 3 A2 Current Amplifier PCA...
Page 149: ...List of Replaceable Parts 8 8 23 5725A 1661 aq38f eps Figure 8 4 A3 High Voltage Amplifier PCA...
Page 153: ...List of Replaceable Parts 8 8 27 5725A 1631 aq39f eps Figure 8 5 A4 Power Supply PCA...
Page 155: ...List of Replaceable Parts 8 8 29 5725A 1650 aq40f eps Figure 8 6 A5 Digital PCA...
Page 159: ...List of Replaceable Parts 8 8 33 5725A 1601 aq41f eps Figure 8 7 A6 High Voltage Sense PCA...
Page 161: ...List of Replaceable Parts 8 8 35 aq32f tif Figure 8 8 A12 Transformer Enclosure Assembly...
Page 162: ...5725A Instruction Manual 8 36 aq33f tif Figure 8 8 A12 Transformer Enclosure Assembly cont...
Page 163: ...List of Replaceable Parts 8 8 37 aq34f tif Figure 8 8 A12 Transformer Enclosure Assembly cont...
Page 164: ...5725A Instruction Manual 8 38 aq35f tif Figure 8 8 A12 Transformer Enclosure Assembly cont...
Page 166: ...5725A Instruction Manual 8 40...
Page 168: ...5725A Instruction Manual 9 2...
Page 169: ...Schematic Diagrams 9 3 9 Figure 9 1 A1 Interconnect PCA 5725A 1611 aq48f eps...
Page 170: ...5725A Instruction Manual 9 4 Figure 9 1 A1 Interconnect PCA cont...
Page 171: ...Schematic Diagrams 9 5 9 Figure 9 1 A1 Interconnect PCA cont...
Page 172: ...5725A Instruction Manual 9 6 Figure 9 2 A2 Current Amplifier PCA 5725A 1650 aq52f eps...
Page 173: ...Schematic Diagrams 9 7 9 Figure 9 2 A2 Current Amplifier PCA cont...
Page 174: ...5725A Instruction Manual 9 8 Figure 9 2 A2 Current Amplifier PCA cont...
Page 175: ...Schematic Diagrams 9 9 9 Figure 9 2 A2 Current Amplifier PCA cont...
Page 176: ...5725A Instruction Manual 9 10 Figure 9 3 A3 High Voltage Amplifier PCA 5725A 1661 aq56f eps...
Page 177: ...Schematic Diagrams 9 11 9 Figure 9 3 A3 High Voltage Amplifier PCA cont...
Page 178: ...5725A Instruction Manual 9 12 Figure 9 3 A3 High Voltage Amplifier PCA cont...
Page 179: ...Schematic Diagrams 9 13 9 Figure 9 4 A4 Power Supply PCA 5725A 1631 aq59f eps...
Page 180: ...5725A Instruction Manual 9 14 Figure 9 4 A4 Power Supply PCA cont...
Page 181: ...Schematic Diagrams 9 15 9 Figure 9 4 A4 Power Supply PCA cont...
Page 183: ...Schematic Diagrams 9 17 9 Figure 9 5 A5 Digital PCA cont...
Page 185: ...Schematic Diagrams 9 19 9 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 186: ...5725A Instruction Manual 9 20 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 187: ...Schematic Diagrams 9 21 9 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 188: ...5725A Instruction Manual 9 22 Figure 9 6 A6 High Voltage Sense PCA cont...
Page 189: ...Schematic Diagrams 9 9 23 aq45f eps Figure 9 7 A12 Transformer Enclosure Assembly...
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