Keithley 6220 Reference Manual page 105

Model 6220/6221 Reference Manual
Source ranging
The source ranging setting determines how the Model 622x selects the current
range based on the sweep steps as follows:
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Sweep delay
The sweep delay parameter determines how long the Model 622x will remain on
each sweep step once the output current is set to the step value. For linear and
logarithmic staircase sweeps, the sweep delay period is the same for every step in
the sweep. For customs sweeps, the sweep delay for each step can be indepen-
dently programmed.
The programmable range for the sweep delay is from 0.001s to 999999.999s.
Sweep count
This setting determines how many sweeps to perform:
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BEST — With this option, the unit will select a single fixed source range
that will accommodate all of the source levels in the sweep. For example, if
the minimum and maximum source levels in the sweep are 1mA and 30mA,
the 100mA source range will be used.
AUTO — With this option, the Model 622x will select the most sensitive
source range for each source level in the sweep. For example, for a 1μA
source level, the 2μA source range will be used, and for a 3μA source level,
the 20μA source range will be used. Note that the output current goes to
zero during the range change.
FIXED — With this option, the source remains on the range it is on when
the sweep is started. For sweep points that exceed the source range capa-
bility, the source will output the maximum level for that range. For example,
if the source is on the 2mA range when the sweep is started, it will remain
on the 2mA range for the entire sweep. If the configured sweep points are
1mA, 2mA, 3mA, 4mA, and 5mA, the sweep will be 1mA, 2mA, 2.1mA,
2.1mA, and 2.1mA.
NOTE The FIXED mode should be used when optimum
sweep speed is a consideration.
FINITE — Use this option to enter a discrete number of sweeps to perform.
INFINITE — Select this option to continuously repeat the configured sweep.
Use the EXIT key to stop the sweep.
Return to Section 4 topics
Sweeps 4-9