Keithley 2450 User Manual

Model 2450
Interactive SourceMeter® Instrument Reference Manual Section 2:
General operation
2450-901-01 Rev. B/September 2013 2-83
High-impedance output-off state
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
Opening the relay disconnects external circuitry from the inputs and outputs of the instrument. To
prevent excessive wear on the output relay, do not use this output-off state for tests that turn the
output off and on frequently.
The high-impedance output-off state should be used when the instrument is connected to a power
source or another source-measure instrument. In some cases, it may also be appropriate for devices
such as capacitors.
When the output is turned on again, the relay has a settling time of approximately 15 ms.
When the high-impedance output-off state is selected, you cannot take measurements using 2-wire
connections.
Zero output-off state
When the zero output-off state is selected, when you turn off the output:
• The measurement sense is changed to 2-wire sense
• The source function is set to voltage
• The source voltage is set to 0
• Set the range to the presently selected range (turn off autorange)
• Program the voltage DAC to zero, and the current DAC to full scale of the present current range.
When the zero output-off state is selected, you can use the instrument as an ammeter because it is
outputting 0 V.
The zero mode is ideal for passive devices such as resistors. In most cases, it can also be used with
energy storage devices such as capacitors and inductors. This mode will discharge capacitors under
test, and remove the charge from semiconductor junctions.
Guard output-off state
Use the guard output-off state when you are measuring a load that uses an active source.
When the guard output-off state is selected and the output is turned off, the following actions occur:
• The measurement sense is changed to 2-wire sense
• The current source is selected and set to 0 A
• The voltage limit is set to 10% full scale of the present voltage range
Output-off states and inductive loads
To protect the instrument from inductive energy, you may need to install a spark gap across the HI
and LO terminals. The instrument does not have internal spark gap protection.

Keithley 2450 Specifications

General

Model	2450
Category	SourceMeter
Voltage Source Range	±200 V
Current Source Range	±1 A
DC Voltage	200 V
DC Current	1 A
Power Output	20 W
Resolution	6.5 digits
Display	5-inch capacitive touchscreen
Operating Temperature	0°C to 50°C
Connectivity	USB, LAN, GPIB
Dimensions	213 mm × 88 mm × 370 mm