Enable Faster Hipot
Before the CH2 tester applies hipot voltage to a DUT, the tester applies the hipot voltage internally and
measures any leakage current internal to the test system. This “internal hipot test” allows the tester null
out minor internal leakages due to humidity and dielectric absorption which could affect measurement
accuracy. When performing hipot with CH2 custom instructions, this internal hipot test will be performed
for the same time as the dwell (or Delay before Measurement) time that is specified in the hipot test for the
DUT
Enable Faster Hipot allows the tester to perform its internal hipot measurement once time when a first
hipot instruction is issued. Subsequent custom hipot commands using the same hipot parameters will use
the same internal system measurement. When Enable Faster Hipot is not used, the system measurement
is made for each hipot instruction.
When attempting to make extremely small current measurements a longer Delay before Measurement
period will increase measurement accuracy.
Hipot & Measure Current
Hipot and Measure Current allows you to specify a precision hipot voltage on one point. If the point is part
of a net, you should choose the point that is the head point of a net, meaning the first system point of the
net. Using the head point will ensure that the CH2 finds other points of the net, and will raise these points
as when the specified point is raised to the hipot voltage. The CH2 will simultaneously sink all other nets
and test points to ground. After the Delay Before Measurement setting has expired, the CH2 will use the
Keithley meter to measure current flow into the hipotted net. You may enable and set both a high and low
limit for the measured current. You may also enable a manual range and specify the current range. (If
range is not specified, auto range will be enabled.)
For operator safety carefully set the Compliance Current and other test settings to minimize the electrical
energy in the test. See safety precautions at the beginning of this section. This custom instruction must
be preceded by both an Attach 2-wire and an Attach 4-wire test instruction.
NPLC
NPLC stands for number of power line cycles. In the US and other countries AC line frequencies are at 60
hertz meaning one power line cycle equates to 16.67 milliseconds. European and other countries use 50
hertz line power where one power line cycle equates to 20 milliseconds. The NPLC setting allows you to
set the measurement period (which occurs after the dwell period) in number of power line cycles. Long
cables, long fixturing, and measuring higher DUT resistances create more susceptibility to AC noise
affecting the measurement reading. Particularly in these circumstances specifying an NPLC value of at
least one or greater for test time will result in higher measurement stability and repeatability. The Keithley
SourceMeter will support an NPLC setting between 0.01 and 10.
Average
Average allows you to specify the number of measurements the tester will make on test points specified by
the custom instruction. Each measurement will be made for a period equal to the NPLC setting. After
making multiple measurements, the tester will then average them. The Average setting can therefore be
used with the NPLC setting to increase the measurement stability and repeatability when it is needed.
However, using higher Average and NPLC settings will result in longer test times, especially when many
connections are being tested.
Other Measurement Options
Disable measurement verification
• By selecting this option, the test will end once a good measurement is found. This speeds up the
test. If not selected, the test will continue testing until several good measurements have been
taken.
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