Keithley 6482 - Equivalent Circuits

2-10 Return to Section Topics 6482-901-01 Rev. A / August 2012
Section 2: Connections Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual
Figure 2-8
Isolated analog output connections
Equivalent circuits
Figure 2-9 shows an equivalent circuit of the analog outputs with the ground connect mode
disabled. Only one channel is shown; the other channel is identical. Note that the analog output
circuit consists of a gain/buffer amplifier, and the analog output LO is connected to floating
common.
Figure 2-10 shows an equivalent circuit with the ground connect mode enabled. In the figure,
because one side of the voltage bias source is connected to chassis ground, analog output LO is
allowed to float up to ±30 V above chassis ground (dependent on the voltage bias source setting).
Figure 2-9
Analog output circuit with ground connect disabled
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DISPLAY
2001 MULTIMETER
DCV ACV DCI ACI Ω2 Ω4
FREQ TEMP
REL TRIG
INFO LOCAL EXIT ENTER
RANGE
RANGE
!
F
R
500V
PEAK
FRONT/REAR
2A 250V
AMPS
CAL
STORE RECALL
CHAN SCAN
FILTER MATH
CONFIG MENU
HI
INPUT
LO
SENSE
Ω 4 WIRE
INPUTS
350V
PEAK
110 0V
PEAK
AUTO
Measuring instrument
Triaxial
cable
Inner
shield
Center
conductor
INPUT
HI
INPUT
LO
Analog devices 3B41-03
wideband isolated
voltage input
HI
LO
Input
V
OUT
V
OUT
Common
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
SERIAL NO.
120
LINE RATING
50, 60Hz
60 VA MAX
FUSE LINE
630 mAT
(SB)
315 mAT
(SB)
100 VAC
120 VAC
220 VAC
240 VAC
CAT I
MADE IN
U.S.A.
OUTPUT ENABLE
RS-232
TRIGGER LINK
INPUT
RATINGS MAX.
30 V @ 20mA
CHANNEL 1
CHANNEL 2
RATINGS MAX.
COMMON
MODE
200V
!
!
IEEE-488
(CHANGE IEEE ADDRESS
WITH FRONT PANEL MENU)
ANALOG
OUT
RATINGS MAX.
30 V @ 20mA
VOLTAGE
SOURCE
OUT
30 V @ 20mA
Model 6482
CHANNEL 1
ANALOG
OUT
-
-
+
Floating channel 1
or channel 2
common
Feedback
ammeter
To analog-to-digital
converter
Bias source
0 to ±10 V or
0 to ±30 V
20 mA maximum
VOLTAGE
SOURCE
OUT
Triaxial
INPUT
20 mA
maximum
Note: One channel shown.
Other channel is identical.
Chassis
ground
HI
LO
Ground
connect
disabled
Chassis
ground
Output
enable
R
F
DUT
LO
HI
Buffer
amplifier
ANALOG
OUT
Chassis
ground
Current flow (I)
+