Avtech AVR-EB4-B, Instructions Manual

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INTRODUCTION
The AVR-EB4-B is a high performance, GPIB and RS232-equipped instrument capable
of generating a +100V / -200V bipolar waveform into a 50 Ohm resistance. Normally, a
diode will be placed in series with this resistance, allowing diode currents of up to +2A
and -4A to be generated.
More specifically, the AVR-EB4-B mainframe generates a 2-20 us wide forward-bias
pulse with amplitude adjustable up to +100V/+2A, which is immediately followed by a 2-
20 us wide reverse-bias pulse with amplitude up to -200V/-4A. The forward and reverse
amplitudes and pulse widths are independently variable. The forward-to-reverse
switching time is < 4.5 ns (10%-90%).
The current waveforms generated by this instrument are suitable for MIL-STD-750E
Method 4031.4 Test Condition B tests. (Avtech can also provide separate test systems
for Condition D tests). In the terminology of this standard, V3 = 0 up to +200V, V4 = 0
up to -200V, R
F
= 50 Ohms, R
4
= 50 Ohms, and R
R
≈ 0. These values differ from the
values suggested in the standard, but the use of 50 Ohm resistances allows common
coaxial cabling to be used for flexible connection arrangement, and greatly reduces the
τ = L / R time constants that plague measurement systems based on the suggested
values. As a result, the measurements are more accurate and more repeatable. (For
additional information about the rationale behind the basic approach, please see
Avtech Technical Brief 15, “A Comparison of Reverse Recovery Measurement
Systems”, at
http://www.avtechpulse.com/appnote .)
The values of I
F
, I
RM
, and i
R(REC)
produced by this instrument are suitable for MIL-STD-
750E Method 4031.4 Test Conditions B1-B4. (Condition B4 is not recommended by
Avtech, however, because the high I
RM
/ i
R(REC)
ratio will make the results more sensitive
to parasitic effects.)
Standard AVR-EB4-B models include one AVX-TRR-MIX diode test jig. The instrument
mainframe is connected to the test jig using one coaxial cable and one DB-9 control
cable. The standard test jig contains a variety of pin sockets and posts, which may be
used to hold the diode device under test (DUT). The test jig has a hinged lid, which
must be fully closed to protect the user from high voltages. The output will be
automatically disabled if the lid is left open. The standard AVX-TRR-MIX test jig will
accommodate TO-220AC (2 lead) packages, DO-style packages with (leads bent at
90°), and standard and reverse-polarity TO-3 packages.
The AVR-EB4-B may also be provided with different or additional a customized test
jigs, to meet particular customer package requirements.
The diode-under-test is connected in series with a 50 Ohm resistance present on the
test jig. In order to achieve the full +2A / -4A amplitude, the diode resistance (dV/dI at
high currents) must be much less than 50 Ohms (i.e., 5 Ohms or lower).
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