Keithley 7752, 7753, 7751 User Manual
www.keithley.com
Model 7751/7752/7753 Switching Modules
User’s Guide
PA-823 Rev. B / Sept 2003
The Models 7751/7752/7753 can be
used with Keithley’s Model 2790.
A GR
EA
TER MEASURE OF CONFIDENCE
Safety Precautions
The following safety precautions should be observed before using
this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions
may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read and follow all installation,
operation, and maintenance information carefully before using the
product. Refer to the manual for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product may be impaired.
The types of product users are:
Responsible body is the individual or group responsible for the use
and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for ensuring that operators are adequately trained.
Operators use the product for its intended function. They must be
trained in electrical safety procedures and proper use of the instrument. They must be protected from electric shock and contact with
hazardous live circuits.
Maintenance personnel perform routine procedures on the product
to keep it operating properly, for example, setting the line voltage
or replacing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state if the operator
may perform them. Otherwise, they should be performed only by
service personnel.
Service personnel are trained to work on live circuits, and perform
safe installations and repairs of products. Only properly trained service personnel may perform installation and service procedures.
Keithley products are designed for use with electrical signals that
are rated Installation Category I and Installation Category II, as described in the International Electrotechnical Commission (IEC)
Standard IEC 60664. Most measurement, control, and data I/O signals are Installation Category I and must not be directly connected
to mains voltage or to voltage sources with high transient over-voltages. Installation Category II connections require protection for
high transient over-voltages often associated with local AC mains
connections. Assume all measurement, control, and data I/O connections are for connection to Category I sources unless otherwise
marked or described in the Manual.
Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present. A good safety practice is to expect
that hazardous voltage is present in any unknown circuit before
measuring.
Operators of this product must be protected from electric shock at
all times. The responsible body must ensure that operators are prevented access and/or insulated from every connection point. In
some cases, connections must be exposed to potential human contact. Product operators in these circumstances must be trained to
protect themselves from the risk of electric shock. If the circuit is
capable of operating at or above 1000 volts, no conductive part of
the circuit may be exposed.
Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When connecting sources to switching cards, install protective devices to limit fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.
When installing equipment where access to the main power cord is
restricted, such as rack mounting, a separate main input power disconnect device must be provided, in close proximity to the equipment and within easy reach of the operator.
For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jumpers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Always
make measurements with dry hands while standing on a dry, insulated
surface capable of withstanding the voltage being measured.
The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equipment may be impaired.
Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications and operating information, and as shown on the instrument or test fixture panels, or
switching card.
When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.
Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.
If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation requires the use of a
lid interlock.
5/02
If or is present, connect it to safety earth ground using the
wire recommended in the user documentation.
!
The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.
The symbol on an instrument shows that it can source or measure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.
The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.
The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and
all test cables.
To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that selected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.
To clean an instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (e.g., data acquisition board for installation into a
computer) should never require cleaning if handled according to instructions. If the board becomes contaminated and operation is affected, the board should be returned to the factory for proper
cleaning/servicing.
Keithley Instruments, Inc.
28775 Aurora Road
Cleveland, Ohio 44139
(440) 248-0400
www.keithley.com
Introduction
The Models 7751, 7752, and 7753 are used with the Model 2790 SourceMeter Switch System. Safety features are integrated into the design of the modules to help safeguard the user and the module. With proper
use of the module and the Model 2790 mainframe, risk of ignition is minimal.
The 7751, 7752, and 7753 modules have a built-in programmable constant I-source to perform low resistance measurements. The 7751 and 7753 modules also have a built-in programmable V-source and an I/V
converter. These features allow the 7751 and 7753 modules to be used with the Digital Multimeter (DMM)
of the Model 2790 to measure high resistance.
NOTE Details on using the 7751, 7752, and 7753 modules are provided in Sections 1, 2, and 5
of the Model 2790 User’s Manual.
Models 7751/7752/7753 Switching Modules
User’s Guide
WARNING It is the responsibility of the user to ensure that external protection is provided, either
by an inherently safe electrical barrier and/or a safety barrier around the DUT or airbag, to prevent injury in case of detonation. The user must take additional precautions
when working with hazardous voltages. A shock hazard exists when >42V is present in
the system.
WARNING DO NOT apply external sources to the 7751, 7752, or 7753 module. Only the sources
provided in the modules should be used for the test system.
Switching matrix
The switching matrix provides four banks of input for the DUT. Each bank provides inputs for 4-wire connections. Each bank also has a built-in short available for HIPOT testing. The switching scheme of the
matrix provides the versatility needed to use the I-source, V-source (7751 and 7753), and the DMM of the
Model 2790.
NOTE The schematic diagram of the 7751/7752/7753 module is provided in Section 2 of the
User’s Manual.
I-source
The programmable I-source of the 7751, 7752, and 7753 modules can be set from 0 to 50mA. The I-source is
used with the DMM of the 2790 to measure low resistance (i.e., bridgewires and shunt bars). The I-source has
a dry circuit clamp that can be used to measure oxide build-up on the contacts of a shunt bar. The dry circuit
clamp limits the test voltage at 20mV to prevent oxide piercing during the measurement.
PA-823 Rev. B / 9-03
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