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Models 2500 and 2502 User’s Manual Limit Testing 11-3

Data ﬂow

All limit tests are part of the CALC7 data block. See Appendix C for an overview on how

limit testing ﬁts into the overall data ﬂow through the Model 2500.

Limit test feeds

You can use the following feeds (data sources) for the software limit tests (Limit 3 to Limit

6): MSR1, MSR2, RATIO, and DELTA. See “Conﬁguring and performing limit tests,”

page 11-16.

Limit 1 and 2 tests (compliance)

These hardware (H/W) tests check the voltage source compliance states of the Model

2500. Limit 1 uses the channel 1 voltage source current compliance current value (20mA)

as the limit, while Limit 2 uses the channel 2 voltage source compliance current as the

limit. At or above the 20mA current limit, the instrument is in compliance. Below the cur-

rent limit, the instrument is not in compliance.

Limit 3 to 6 tests

These software (S/W) tests are used to determine if a DUT is within speciﬁed high and

low limits. Typically, the Limit 3 test is used to test for coarse tolerance limits, and the

Limit 4 through Limit 6 tests are used for progressively ﬁner tolerance limits.

For example, assume you want to sort diodes into three groups: 10%, 15%, and >20% cur-

rent tolerance. To do this, conﬁgure the Limit 3 test for 20% HI and LO limits and Limit 4

for 15% HI and LO limits. If Limit 3 fails, the handler places the DUT in the bin labeled

>20%. If Limit 3 passes, the Limit 4 test is run. If Limit 4 fails, the DUT is placed in the

bin labeled 15%. If Limit 4 passes, the handler places the DUT in the bin labeled 10%.

Although Limit 1 and Limit 2 (discussed above) are dedicated to channels 1 and 2 respec-

tively, the Limit 3 through Limit 6 tests can be used with channel 1, channel 2, RATIO, or

DELTA measurements by selecting the corresponding data feed. See “Conﬁguring limit

tests,” page 11-16, as well as Appendix C, “Data Flow.”

Limit test modes

There are two modes of operation for limit tests: grading and sorting. For Limit 1 and 2

tests (compliance), operation is similar for both limit test modes. If Limit 1 or 2 test fails,

the FAIL message is displayed and the testing process for that DUT (or DUT element) is

terminated. A pass condition allows the testing process to proceed to the next enabled limit

test.

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Keithley 2500 User Manual

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