Avtech AVR-EB4-B, Instructions Manual, Page: 37 / 83

RUS460 RESULTS
The EDI RUS460 is a 5A, 600V DO-204AR ultrafast rectifier. With the amplitudes set to
+100V and -200V, the following reverse recovery waveform is obtained at the test jig
"OUT" terminal:
5 V/div ( = 1 A/div), 20 ns/div.
20%-80% switching time shown.
S/N 11713. 5m cable used.
The above waveform shows the transition from a forward current of +2A to a reverse
current of -4A. The reverse transient lasts for approximately 40 ns under these
conditions, and then ends rather abruptly. This abrupt termination of the reverse
transient is somewhat unusual, and is referred to as a "hard" or "step" transient. Most
modern diodes are optimized to provide a "soft" transient, with a more gradual decay of
the reverse current from its peak value to zero.
The fast switching time of the hard transient causes transmission line reflections to
occur. These reflections repeat in an exponential decay pattern, until they are no longer
detectable. The time between reflections is governed by the length of coaxial cabling
(normally 5 meters) connecting the mainframe to the output module. These reflections
can normally be ignored, since they occur after the end of the "interesting" part of the
transient where measurements are made. The coaxial cable can be extended to move
the reflection away from the switching transient.
In this test, a 5m coaxial cable was used. If the 60 cm cable were used, the following
waveform would be obtained:
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