6482-901-01 Rev. A / August 2012
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10-3
Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual
Section 10: Limit Testing
Limit 1 and 2 tests (compliance)
The limit 1 and limit 2 tests are hardware (H/W) tests that check the voltage source compliance
states of the Model 6482. Limit 1 uses the channel 1 voltage source current compliance current
value (20 mA) as the limit, while Limit 2 uses the channel 2 voltage source compliance current as
the limit. At or above the 20 mA current limit, the instrument is in compliance. Below the current
limit, the instrument is not in compliance.
Limit 3 to 6 tests
The limit 3 through limit 6 tests are software (S/W) tests that 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% current
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 :CALCulate7:LIMit3:FAIL? command will return a 0 (limit test passed).
If Limit 3 passes, the Limit 4 test is run. If Limit 4 fails, the :CALCulate7:LIMit4:FAIL? command will
return a 1 (limit test failed). If Limit 4 passes, the :CALCulate7:LIMit4:FAIL? command return a 0
(limit test passed).
Although Limit 1 and Limit 2 (discussed above) are dedicated to channels 1 and 2 respectively, 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
, as well as
Limit tests
If the limit 1 or limit 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.
Each enabled software test (limit 3 through 6) is performed until a test passes. When a test
passes, the PASS message is displayed and the testing process for that DUT is terminated.
Operation overview
Limits operation is detailed by the flow chart in
. A test is only performed if it is enabled;
if a test is disabled, operation proceeds to the next test. The following assumes the first three limit
tests are enabled.
With the limit tests properly configured, turn the Model 6482 output on, and then press the
LIMIT
key. The testing process will start when an SOT signal SOT (start-of-test) strobe pulse is received
by the Model 6482. Note that if the trigger model is not set to accept an SOT signal, testing will
start when the
LIMIT
key is pressed. Pressing the
LIMIT
key a second time terminates the testing
process.
As shown in the flow chart, limit tests are performed after a measurement conversion.
Summary of Contents for 6482
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