2-20 Return to Section Topics 2600AS-901-01 Rev. B / September 2008
Section 2: DUT Test Connections Series 2600A System SourceMeter® Instruments Reference Manual
Test fixture
A test fixture can be used for an external test circuit. The test fixture can be a metal or nonmetallic
enclosure, and is typically equipped with a lid. The test circuit is mounted inside the test fixture.
When hazardous voltages (>30 Vrms, 42 Vpeak) will be present, the test fixture must have the
following safety requirements:
WARNING To provide protection from shock hazards, an enclosure should be
provided which surrounds all live parts.
Nonmetallic enclosures must be constructed of materials suitably
rated for flammability and the voltage and temperature requirements of
the test circuit.
For metallic enclosures, the test fixture chassis must be properly
connected to safety earth ground. A grounding wire (#18 AWG or
larger) must be attached securely to the test fixture at a screw terminal
designed for safety grounding. The other end of the ground wire must
be attached to a known safety earth ground.
Construction material: A metal test fixture must be connected to a known safety Earth Ground as
described in the above WARNING. A nonmetallic test fixture must be constructed of materials that
are suitable for flammability, voltage, and temperature conditions that may exist in the test circuit.
The construction requirements for a nonmetallic enclosure are also described in the WARNING
above.
Test circuit isolation: With the lid closed, the test fixture must completely surround the test
circuit. A metal test fixture must be electrically isolated from the test circuit. Input/output
connectors mounted on a metal test fixture must also be isolated from the test fixture. Internally,
Teflon standoffs are typically used to insulate the internal pc-board or guard plate for the test circuit
from a metal test fixture.
Interlock switch: The test fixture must have a normally-open interlock switch. The interlock switch
must be installed so that when the lid of the test fixture is opened, the switch will open, and when
the lid is closed, the switch will close.
WARNING When an interlock is required for safety, a separate circuit should
be provided that meets the requirements of the application to
reliably protect the operator from exposed voltages.
The output enable pin on the digital I/O port on the Models 2601A and
2602A are not suitable for control of safety circuits and should not be
used to control a safety interlock. The Interlock pin on the digital I/O
port for the Models 2611A, 2612A, 2635A, and 2636A can be used to
control a safety interlock.
Floating an SMU
Using an external source in the test system may require that a Series 2600A SMU float off chassis
earth ground. An example of such a test system is shown in
Figure 2-31, which includes an
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