I-4
Applications Guide
Model 6485 Picoammeter Instruction Manual
The 1mV voltage burden caused a 20% current reduction. Percent error in a measured
reading (I
M
) due to voltage burden can be calculated as follows:
The voltage burden of Model 6485 depends on the selected range (see specifications).
Voltage burden may be reduced by performing the voltage offset correction procedure.
Voltage offset correction procedure
NOTE
To maintain specified operation, any time there is a substantial change in the
ambient temperature, the voltage offset procedure should be performed and
saved.
1.
Press the MENU key to display the following:
CAL: VOFFSET
2.
Press ENTER. The instrument will prompt as follows:
INPUT CAP
3.
It is not necessary to disconnect signal cables from the 6485, but it is recommended
that signal currents be reduced to zero if possible. During the calibration, the input
impedance will be 3.5M
Ω
, therefore continued signal currents will present a corre-
sponding voltage to the DUT.
4.
Press ENTER to complete offset voltage calibration.
5.
Press EXIT to return to normal display.
NOTE
Like the other calibration procedures, this calibration is not permanently stored
until CAL:UNLOCK and CAL:SAVE have been performed. Saving the results of
this calibration at a temperature other than that at which the Model 6485 will be
used will adversely affect measurement results.
I
M
% error
100%
V
S
/V
B
(
)
----------------------
=
Summary of Contents for 6485
Page 20: ......
Page 24: ......
Page 44: ...1 20 Getting Started Model 6485 Picoammeter Instruction Manual ...
Page 66: ...3 6 Measurements Model 6485 Picoammeter Instruction Manual ...
Page 138: ...9 20 Remote Operation Model 6485 Picoammeter Instruction Manual ...
Page 159: ...11 CommonCommands ...
Page 164: ...11 6 Common Commands Model 6485 Picoammeter Instruction Manual ...
Page 165: ...12 SCPISignalOriented MeasurementCommands ...
Page 190: ...14 12 SCPI Reference Tables Model 6485 Picoammeter Instruction Manual ...
Page 214: ...16 14 Calibration Model 6485 Instruction Manual ...
Page 219: ...A Specifications ...
Page 221: ...B StatusandErrorMessages ...
Page 227: ...C GeneralMeasurement Considerations ...
Page 233: ...D DDCEmulationCommands ...
Page 247: ...E ExamplePrograms ...
Page 250: ...E 4 Example Programs Model 6485 Picoammeter Instruction Manual ...
Page 251: ...F IEEE 488BusOverview ...
Page 266: ...F 16 IEEE 488 Bus Overview Model 6485 Picoammeter Instruction Manual ...
Page 267: ...G IEEE 488andSCPI ConformanceInformation ...
Page 311: ......