Model 2657A High Power System SourceMeter® Instrument Reference Manual
Section 2: General operation
2657A-901-01 Rev. B/December 2012
2-65
Front panel sense mode selection
To check or change the sense mode from the front panel:
1. Press
the
CONFIG
key.
2. Press
the
SRC
or
MEAS
key. You can access and set the Model 2657A sense mode from either
the V-SOURCE or the V-MEAS menu items.
3. If you pressed the SRC key: select
V-SOURCE
>
SENSE-MODE
, and then press the
ENTER
key
or the navigation wheel
.
If you pressed the MEAS key: select
V-MEAS
>
SENSE-MODE
, and then press the
ENTER
key
or the navigation wheel
.
4. Select
2-WIRE
or
4-WIRE
as needed, and then press the
ENTER
key or the navigation wheel
.
Selecting the sense from a remote interface
To select the remote sense from a remote interface:
Set the
smua.sense
attribute to control the sense state by remote. The programming example below
illustrates how to configure the Model 2657A for 4-wire remote sensing:
smua.sense = smua.SENSE_REMOTE
See
Remote source-measure commands
(on page 7-1)
for details.
Overvoltage protection (OVP)
You can enable overvoltage protection (OVP) to restrict the maximum voltage level of the Model
2657A. If the configured OVP level is reached:
•
The Model 2657A goes into overvoltage protection mode
•
The output clamps to the OVP level
•
All measurements taken are returned as 9.92e37
•
The front panel displays OVP instead of a value
OVP protects the DUT from inadvertently applied high voltage levels. This can be caused by a sense
lead becoming disconnected (or broken) during 4-wire sense applications. During 4-wire sense
applications, the Model 2657A may interpret a removed sense lead as a decrease in voltage and
increase the output to compensate (see
4-wire remote sensing connections
(on page 2-47)). With
OVP configured, the voltage between the HI and the LO terminals will not exceed the specified value
regardless of the voltage present on the sense leads.
The OVP setting takes precedence over any compliance setting, but may be used in conjunction with
compliance. If the SMU is sourcing voltage and encounters both a current compliance and an
overvoltage condition, the overvoltage protection will take priority. Once enabled, OVP is always on
until disabled. This provides protection for both local and remote sense measurements.
The valid OVP range is between 300 V and 3000 V. Setting OVP to a value outside of this range will
generate error code -224, "Illegal Parameter Value."
The following topics describe how to enable, set, and disable OVP.
Summary of Contents for 2657A
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