What Are Source Limits; What Is Offset Compensation; What Is A Configuration List - Keithley 2461 Reference Manual

Section 9: Frequently asked questions (FAQs)

What are source limits?

The source limits (also known as compliance) prevent the instrument from sourcing a voltage or
current over a set value. This helps prevent damage to the device under test (DUT).
The values that can be set for the limits must be below the setting for the overvoltage protection limit.
This limit can also be restricted by the measurement range. If a specific measurement range is set,
the limit must be more than 0.1 % of the measurement range. If not, an event is generated and the
limit is automatically changed to an appropriate value for the selected range. If you set the
measurement range to be automatically selected, the measurement range does not affect the limit.
If you attempt to change the source limit to a value that is not appropriate for the selected source
range, the source limit is not changed and a warning is generated. You must change the source
range before you can select the new limit.
The lowest allowable limit is based on the load and the source value. For example, if you are sourcing
1 V to a 1 kΩ resistor, the lowest allowable current limit is 1 mA (1 V/1 kΩ = 1 mA). Setting a limit
lower than 1 mA limits the source.
If the source output exceeds the source limit:
•
On the Home screen, LIMIT is displayed to the right of the source voltage.
•
The Source value changes to yellow.
The source is clamped at the maximum limit value. For example, if the measurement limit is set to 1 V
and the measurement range is 2 V, the output voltage is clamped at 1 V.

What is offset compensation?

Offset compensation is a measuring technique that reduces or eliminates thermoelectric EMFs in
low-level resistance measurements. The voltage offsets because of the presence of thermoelectric
EMFs (V
EMF
To overcome these offset voltages, you can use offset-compensated ohms.

What is a configuration list?

A configuration list is a list of stored instrument settings. You can restore these instrument settings to
change the active state of the instrument. Configuration lists allow you to record the active state of the
instrument, store it, and then return the instrument to that state as needed.
If you are using TSP, configuration lists run faster than a script that is set up to configure the same
settings.
The Model 2461 supports source configuration lists and measure configuration lists, making it
possible to sequence through defined source settings, measure settings, or both.
Each configuration list consists of a list of configuration indexes. A configuration index contains all
instrument source or measure settings that were active at a specific point. You can cycle through the
configuration indexes using a trigger model.
For more detail, see
9-14
) can adversely affect resistance measurement accuracy.
Configuration lists
Model 2461 Interactive SourceMeter® Instrument Reference Manual
(on page 3-30).
2461-901-01 A/November 2015