Keithley 237

SECTION3
IEEE-488
Reference
3-20
Figure 3-2
shows
the
effect
of
a
bias
command
on
a fixed level
pulsed
sweep. First
the
bias
level is
set
with
the
B
command,
then
the
sweep
is
programmed
with
a Q4
command.
The
first
example
program
lists
the
necessary
commands
to
generate this
waveform.
CAUTION
When
changing
the
bias
level,
the
SMU
will
first
output
the
old
value
for
10msec
before
going
to
the
new
value.
To
pre-
vent
damage
to external
equipment
and
circuitry,
make
sure
your
test
routine
accounts for
that
lOmsec delay.
If
you
tum
the
output
off
(standby)
and
then
change
the
bias
level,
the
output
will
momentarily
(lOmsec) go
to
the
old
bias
level
when
the
output
is
turned
back
on
(operate).
To
prevent
a
potentially
damaging
output
level, set
the
bias
level to
0
before
turning
the
output
off.
When
the
output
is
turned
back
on,
0
will
be
output
for
10msec
before
going
to
the
new
bias
level.
To
change
the
bias
level as quickly as possible,
you
must
execute
the
B
command
imme-
diately. This is
done
by
sending
the
X
command
immediately
after
the
B
command.
For
example, to
change
the
bias
level to
OV
as quickly
as
possible,
send
the
following com-
mand
string:
BO,O,OX.
Including
other
commands
in
the
string
(after the B
command)
may
result
in
additional
delay
in
bias
level changes.
NOTE
Because of the
delay
in
bias level changes,
do
not
use
the
B
command
to
generate
a
pulse
waveform.
Use
the
sweep
func-
tion to create pulses,
even
if
the
sweep
contains
only
one
pulse.
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Source
BS.
2.
~
~oint
Value
lo«/1-
"".2.8.2.2.~00.100
1
2V
100.,...,
2
!N
100moec
3
4V
100.,...,
•
!N
100 msec
5
6V
100 msec
6
sv
100 msec
7
sv
100.,...,
8
5V
100
msec:
Figure
3-2.
Bias
Operation