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FEC200 VF Test

The typical VF test is very simple. Consider the sample below.

  • TESTn VF 1A <.98V

This uses the default pulse width of 300ÁS and a single maximum limit. The readout uses the 1.6383V scale. You could have used up to the maximum forcing current of 40A for the FEC200 or 8A for the FEC100.

VF as VZ

You can measure VZ using the forcing supply for VF by specifying VF with the F1 function added to reverse the orientation, as in the following.

  • TESTn VF 5A >9.5V <10.5V F1

The advantage is that the VF supply can produce significantly more power than the reverse supply can and is faster as well. Don't forget that once reversed with F1 the orientation remains reversed until another F1 is used.

Note that the example would use the 16.383V scale or the optional 24.574V scale if your tester is so equipped. See the derating chart for the relationship between maximum current, voltage, and pulse width. The example above is well within the limits.

You can increase the pulse width with the T function as below. This may give significantly lower VF readings and some specs specify a wider pulse. The default SOAK TIME of zero is interpreted as 300ÁS. You can program longer times in 1mS increments.

  • TESTn VF 10A <.98V T8

SURGE is a variation of the VF test where the current pulse is an 8.3mS halfsine.

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Last Updated September 12, 2007
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