Keithley 4200-SCS, User Manual, Page: 46 / 335

1-36 Return to Section Topics 4200-900-01 Rev. K / February 2017
Section 1: Getting Started Model 4200-SCS User’s Manual
Connecting DUTs
Test fixtures
There are two types of test fixtures for the 4200-SCS:
• Low-voltage fixtures (less than ±20 V) and high-voltage (greater than ±20 V).
• High-voltage fixtures require extra precautions to ensure there are no dangerous shock
hazards.
WARNING
To avoid exposure to high voltages that could result in personal injury or
death, whenever the interlock of the Model 4200-SCS is asserted, the FORCE
and GUARD terminals of the SMUs and preamps should be considered high-
voltage, even if they are programmed to a non-hazardous voltage current.
Testing with less than ±20 V with SMUs
A test fixture equipped with three-lug triax connectors is necessary to connect the 4200-SCS
discrete device for testing.
Figure 1-31 shows a basic test fixture to use with a two-terminal device.
For best performance when testing with less than ±20 V follow these standard industry practices:
• Use a metal test fixture
• Connect the metal fixture to COMMON
• Mount the DUT on high-resistivity terminals (for example, Teflon)
• Guarding will reduce leakage and parasite capacitance that degrades measurement quality
The Keithley Instruments Low Level Measurements Handbook provides an in-depth discussion
about guarding and other techniques that are useful for building quality test fixtures.
Contact a Keithley Instruments sales or service office to obtain a copy.
Figure 1-31
Typical test fixture
HI
Guard
Common
HI
Guard
Common
DUT
Interlock
Test Fixture
SMU1
SMU2
Connect to safety earth
ground using #18 AWG
wire or larger