Load
wire inductance
If the
load wire is
long
or has a
large loop, the wire inductance
is increased. Conse-
quently, the cun-ent
variation
that results when switching
occurs will cause a large
voltage drop.
In
such
condition, the
input voltage may fall below the minimum operating voltage
of the PLZ'U causing
the current
waveform
to be distorted. In some cases, the input
voltage may exceed the
maximum input voltage and cause damage to
the PLZ-U.
You must be careful
especially when
the slew
rate
setting
is high or
switching
is per-
formed using large
cuiTents through parallel operation.
To
prevent problems,
connect the PLZ-U and the equipment
under
test using the
shortest twisted wire
possible to keep
the voltage caused by inductance between the
minimum operating
voltage and the
maximum input
voltage range
or set
a low slew
rate. The voltage
generated by
inductance and current
variation is expressed using
the following equation.
E
[V]
=
L [pH]
X slew rate [A/ps]
E:
Voltage
generated by the wire
inductance
L: Wire
inductance
(1
pH/m is
rough estimate.)
Fig.
2-9
Voitage
generated by
inductance and
current variation
In the case
of DC
operation also, the phase
delay of the
current may cause
instabil-
ity in
the PLZ-U
control inducing
oscillation. In this case
also, connect the
PLZ-U
and the
equipment
under test using the
shortest twisted
wire possible.
If
only DC
operation is
required, a capacitor
and a resistor may
be connected to
the
load
input terminal as shown
in Fig.
2-10
to
alleviate oscillation. In
this case, use
the
capacitor within its
allowable ripple
current.
Example: R
=
10 Q
and
C=l00oF
Fig,
2-10
Length
of wiring
Installation and
Preparation
2-13
PLZ-U
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