Scientific 5000 Series, Manual, Page: 317 / 360

APP-001
MODEL 5000 SERIES MANUAL
Version 1.23
14-3
14.1 APP-001 Limit (clamp) the voltage in Triac VD
tests
The Triac VD+ and VD- tests can result in the measured voltage being very high
(over 1KV or 2KV), which can cause arcing internally in the device or between the
probes. The STI software can be used effectively as a clamp to limit this voltage
through the use of calculation test steps. Figure 14-2 is an example test program
illustrating this method. Figure 14-3shows the sort plan used to obtain the desired
binning results. Please refer to the STI Manual for entering and editing test steps
and setting up the bin plan.
In this example, test step 1 is an SCR IDRM test that measures the current at a
specified voltage. The voltage for this test should be slightly greater than maximum
desired voltage. For this test step we have selected the maximum desired voltage to
be 900 volts and set VDRM at 901 volts.
Test step 2 is the actual Triac VD+ test desired. The voltage limit is unimportant, as
this step will not be used in the sorting. The limit should be set to something close to
the actual value to minimize autoranging time.
Test step 3 does the real work. This is a calculation that actually works as follows:

Test step 1 is run and the result compared to, in this case, 1mA (0.001)

If the result of test step 1 is less than 1mA, then the result of 901V is returned
without running test step 2

If the result of test step 1 is greater than or equal to 1mA, then test step 2 is
run and the result of test step 2 is reported.

Test steps 4 and 5 provide a means of sorting the device by the VD+ voltage.

Test steps 6 through 10 repeat the above for VD-
To simplify:

Enter the not to exceed (clamp) voltage in steps 1 and 3 (positive) and steps
6 and 8 (negative)

Enter sort 1 voltage limit (steps 3 and 8)

Enter sort 2 voltage limit (steps 4 and 9)

Enter sort 3 voltage limit (steps 5 and 10)

Set binning as sown in Figure 14-3 (note: must use the STI Bin/Sort mode)

Add additional sorts and bins as required