Measure high-voltage logic inputs with your ATE Peter Sarson,
ams- July 10, 2012 Sometimes a test engineer has to use some
creativity to overcome challenges. This article details such a
situation where a 20 V digital signal from a power management IC
had to be measured by an automatic tester with a 6 V digital
input capability. In a perfect world, the test system would have
the appropriate resources. But, this unusual application
required additional resources were not available because the
production volume didn't justify it. One potential solution is
to use a high-voltage analog resource for this measurement. This
option was discarded due to the extra test time, coding
complexity, and additional time needed for debugging and
ensuring reliability. An obvious solution is to use a voltage
divider and reduce the voltage by a ratio. Care must be taken
because devices with a very low output drive can't overcome the
parasitic capacitances of the test system. Therefore the signal
needs buffering. The next step was t