What Is The Output-Off State - Keithley 2461 Reference Manual

Model 2461 Interactive SourceMeter® Instrument Reference Manual

What is the output-off state?

When the source of the instrument is turned off, it may not completely isolate the instrument from the
external circuit. You can use the output-off setting to place the Model 2461 in a known, noninteractive
state during idle periods, such as when changing the device under test. The appropriate output-off
state depends on your system and the device under test. Different types of connected devices or
loads require different behaviors from the Model 2461 when the output is turned off. For example, a
passive device such as a diode is not affected by a 0 V source connected across its terminals when
the output is turned off. However, connecting a 0 V source to the terminals of a battery causes the
battery to discharge.
The output-off states that can be selected for a Model 2461 are normal, high-impedance, zero, or
guard.
Carefully consider and configure the appropriate output-off state, source, and source limits before
connecting the Model 2461 to a device that can deliver energy, such as other voltage sources,
batteries, capacitors, or solar cells. Configure recommended instrument settings before making
connections to the device. Failure to consider the output-off state, source, and source limits may
result in damage to the instrument or to the device under test (DUT).
When the Model 2461 is set to the normal output-off state, the following settings are made when the
source is turned off:
•
The measurement sense is set to 2-wire
•
The voltage source is selected and set to 0 V
•
The current limit is set to 10 % of the full scale of the present measurement function autorange
value
•
If source readback is off, Output Off is displayed in the Home screen Source area
•
If source readback is on, the actual measurement is displayed in the Home screen Source area
•
If measurement is set to resistance, dashes (--.----) are shown in the Home screen Source area
•
The Source button on the Home screen shows the value that will be sourced when the output is
turned on again
When the zero output-off state is selected and you turn off the output:
•
The measurement sense is changed to 2-wire
•
The voltage source is selected and set to 0
•
The range is set to the presently selected range (turn off autorange)
•
If the source is voltage, the current limit is not changed
•
If the source is current, the current limit is set to the programmed source current value or to 10 %
full scale of the present current range, whichever is greater
When the zero output-off state is selected, you can use the instrument as an ammeter because it is
outputting 0 V.
When the high-impedance output-off state is selected and the output is turned off:
•
The measurement sense is set to 2-wire
•
The output relay opens, disconnecting the instrument as a load
2461-901-01 A/November 2015
Section 9: Frequently asked questions (FAQs)
9-11