Keithley 2790, Reference Manual

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2-2 Model 2790 SourceMeter
®
Switch System Reference Manual
Test System Safety Precautions
The Model 2790 SourceMeter
®
switch system is designed for applications that include
very sensitive devices that can be damaged or destroyed by excessive energy levels. There-
fore, the mainframe and all plug-in modules have been designed with this fact in mind to
ensure reliable, accurate performance with a minimum level of risk of damage to the
device under test. However, the inherent flexibility of the Model 2790, particularly when
augmented by the addition of a 7702 switch module, can cause certain compromises to sys-
tem reliability if certain precautions are NOT understood and taken.
In order to preserve and maintain specified performance when the Model 2790 is used in a
mixed-mode system application, the following caveats must be strictly complied with:
1. External energy sources should never be applied directly to a 7751, 7752, or 7753
module for any reason. Damage to the module and any connected devices under
test can result due to the application of improperly selected or performing external
energy sources.
2. For applications that include the use of mainframe measurement functions in addi-
tion to those using 7751/7752/7753 modules, interconnected using a Model 7702
switch module, external energy sources can, in the case of a single hardware or
software programming error or fault, become connected directly to unintended
device under test connections. In such system applications, it is the system
designer/builders sole responsibility to ensure that under all such potential fault
conditions, no hazardous or damaging situations are created.
3. The 7702 module is designed to handle DC peak voltages up to 300V generated by
external and potentially unlimited energy type sources. When the 7702 module is
used in conjunction with the 7751/7753 module, it can be used safely up to the full
output voltage capability of the 7751/7753 V-source (500V DC peak). This DOES
NOT imply the 7702 module can be used with EXTERNAL SOURCES (i.e., non-
7751/7753 derived) above 300V DC peak.
4. Since the Model 2790 was designed for a number of sensitive device applications,
reasonable precautions were taken in the designs of all Keithley mainframes and
modules. However, addition of external equipment cannot be 100% anticipated by
Keithley and therefore becomes the sole responsibility of the end system designers
and builders regarding the creation of any hazardous or damaging situations and
such implies to personal, product safety, or other business implications.
Close/open overview
There are two modes of close/open operation:
• Multiple channel operation — This mode of operation provides individual control
of each switching module channel.
• System channel operation — When you close a system input channel (or channel-
pair) on the Model 7702 switching module, other channels close automatically to
internally connect it the DMM of the Model 2790. Note that system channel opera-
tion is not available for the Models 7751, 7752, and 7753 switching modules.