+
Plotter
Source
Measure
Unit
Figure
2-17.
IEEE-488
Connections
2.6
TYPICAL SWITCHING
CONFIGURATIONS
For multiple OUT (device
under
test) testing, a
number
of
switching
and
matrix cards can
be
used
with
one
or
more
Source Measure
Units. The information
in
this
paragraph
explains
how
to connect these cards to the Source Meas-
ure
Unit
and
a test fixture.
WARNING
When
using
remote sense,
lethal
voltage
will
appear
at
OUTPUT
HI
and
GUARD
if
a
sense
lead
is
open.
This
voltage can cause
in-
jury
or
death,
and
damage
to
switching cards
and
DUT.
Thus,
ALWAYS
place
the
Source
Measure
Unit
in
standby
before changing a
switch configuration.
2.6.1
Model7058
Low
Current
Switching Card
The Model7058
is
a
10
channel, single-pole,
low
current
switching card (
<1
pA
offset current)
that
can
be
con-
trolled
by
a Model705
or
706
scanner. Figure 2-18 shows
an
example of a single Source Measure
Unit
system using
the Model 7058 switching card.
In
this
configuration,
Source Measure
Unit OUTPUT
HI
is
switched
by
the card
to
10
OUTs. The Source Measure
Unit
is
connected to one
+
Source
Measure
Unit
SECTION2
Operation
of
the switching cards
OUTPUT
connectors (via the
Model6172 adapter)
and
the
10
channels of the card are
connected to the test fixture. A
banana
plug
cable
is
used
to connect
Source
Measure
Unit OUTPUT LO to the test
fixture. However, for better shielding, the
OUTPUT LO
and
SENSE LO
triax connector
on
the Source Measure
Unit
along
with
a triax cable can
be
used to make the con-
nection to the test fixture. Note
that
the switching card
jumpers from signal to
guard
on
unselected channels
must
be
removed to keep
OUTPUT
HI
and
GUARD
from
shorting together.
A single Model7058 can handle only one connector of the
Source
Measure
Unit.
More complex test systems will re-
quire additional switching cards. For example,
If
the test
configuration
is
modified to utilize
an
additional Source
Measure
Unit, OUTPUT
HI
of the second
Source Meas-
ure
Unit
would
have
to
be
switched
by
a second Model
7058card.
Figure 2-18 shows
OUTPUT LO
of the Source Measure
Unit
connected directly to the common side of the OUTs
bypassing the switching card.
If
it
were desired to switch
OUTPUT LO to increase flexibility of the test system,
an
additional switching card, such as the Model 7056 Gen-
eral Purpose Scanner
Card
would
be
required.
Source
Measure
Unit OUTPUT LO
would
be
connected to the
second switching card.
While the first card
would
be
used
exclusively to switch
OUTPUT
HI, the second card
would
be
used
exclusively
2-21
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