2606B System SourceMeter® Instrument Reference Manual
Section 2: General operation
2606B-901-01 Rev. B / May 2018
2-63
Construction material
: A metal test fixture must be connected to a known protective earth (safety
ground) as described in the above
WARNING
. A nonconductive 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 nonconductive 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 be isolated from the test fixture. Internally, Teflon standoffs are typically
used to insulate the internal printed circuit 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. The 2606B digital I/O port provides an output enable line. When
properly used with a test fixture, the output of the 2606B turns off when the lid of the test fixture
opens.
See
(on page 3-78) for information on the digital I/O port.
Floating a SMU
Using an external source in the test system may require that a 2606B source-measure unit (SMU)
float off chassis earth ground. An example of such a test system is shown below, which includes an
external voltage source. Notice that output low of the external voltage source is connected to chassis
earth ground.
For the test circuit shown below, the 2606B must float off chassis earth ground. As shown, LO of the
2606B is fl10 V above chassis earth ground. If LO of the 2606B was instead connected to
chassis ground, the external voltage source would be shorted to the chassis ground.
Figure 35: Floating a SMU