3-16 DUT Test Connections Series 2600 System SourceMeters Reference Manual
2600S-901-01 Rev. A / May 2006 Return to Section 3 topics
Floating an SMU
Using an external source in the test system may require that a Series 2600 SMU
float off chassis earth ground. An example of such a test system is shown in
Fig-
ure 3-16, which includes an external voltage source. Notice that output low of the
voltage source is connected to chassis earth ground.
For the test circuit shown in Figure 3-16, the Series 2600 must float off chassis
earth ground. As shown, SMU LO of the Model 622x is floating +10V above
chassis earth ground. If SMU LO of the Model 622x was instead connected to
chassis ground, the external voltage source would be shorted through chassis
ground.
The Series 2600 connections for the floating configuration (Figure 3-16) are
shown in Figure 3-17. In order to float the SMU, Input/Output LO must be isolated
from chassis ground. This is accomplished by NOT connecting Input/Output LO to
chassis ground.
The external voltage source in Figure 3-16 and Figure 3-17 can instead be an
SMU of a second Series 2600 instrument. Keep in mind that if the combined
outputs of the sources exceeds 42V, then a safety shield will be required for the
DUT (see the following WARNINGS).
WARNING The maximum floating (common mode) voltage for an SMU is
±250V. Exceeding this level may cause damage to the
instrument and create a shock hazard.
Using an external source to float an SMU could create a shock
hazard in the test circuit. A shock hazard exists whenever >42V
peak is present in the test circuit. Appropriately rated cables or
insulators must be provided for all connections to prevent
access to live parts.
When >42V is present, the test circuit must be insulated for the
voltage used or surrounded by a metal safety shield that is
connected to a known safety earth ground and chassis ground
(see “
Safety shield” earlier in this section).
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