V
MON
shows that the pulser is generating a fast-switching pulse.
V
IN
shows a “bump” in the waveform on the + to – transition, due to the effect of the
storage time and the 50Ω output impedance of the pulser. This is not a concern, as
V
CURR-MON
shows that the desired current is in fact obtained (-2.5A).
I MPEDANCE NOTES
The “bump” in the waveform noted above might be avoided if the pulse generator had a
low output impedance. However, some tests explicitly require a 50 Ohm output
impedance in the pulse generator (such as MIL-PRF-19500/498E, MIL-S-19500/537).
MIL-PRF-19500/464G does not specify a particular output impedance. The tests above
show the 50Ω output impedance produces good results with MIL-PRF-19500/464G.
Some tests call for a 51Ω resistance to ground to be added at V
IN
. This may help
suppress any observed transmission line ringing when the transistor switches off
(becoming an open circuit, mismatching the transmission line).
T
RANSITION TIME NOTES
The internal pulse generator has a 20%-80% switching time of 20 ns or less. The
transitions times observed at V
IN
may be higher, due to the RC time constant effect of
R
OUT
and any parasitic capacitance in the user's cabling.
Some tests call for extremely fast switching times (< 2ns for MIL-PRF-19500/498E).
However, this is not truly necessary, because the parameters being tested are
measured on the scale of microseconds. A 20 ns switching time will not affect the
measurements in any meaningful way.
28
Summary of Contents for AVR-D3-B
Page 36: ...PCB 158R5 LOW VOLTAGE POWER SUPPLY ...
Page 37: ...PCB 168C HIGH VOLTAGE POWER SUPPLY ...
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Page 43: ...PERFORMANCE CHECK SHEET ...