Vishay SCR and Diode Resistance Measurements Application Note
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SCR
and
Diode Resistance Measurements
with
a Volt-Ohmmeter
Introduction
Many
users
.
proper
equipment
parameter
ventional
(VOM)
battery
is
sometimes
acceptable
based
upon a resistance
measurement
erroneous
erroneous
of this
Application
YOM
Measurements
The
semiconductor
are
generally
the
blocking
"on-state"
resistance
across
the
diode
and
seR
since
the
anode-cathode
present
blocking
Powerex
voltage
of SeRs
measurements.
from,
conclusions.
measurements
voltage
characteristics.
measurements
anode-cathode
across
its
and
to
make
operated
used
unacceptable
of
this
type
The
Information.
measurements
made
with a VOM
rather
the
gate-cathode
characteristic
of a
diode.
diodes
ratings
from
diodes
to
reading.
can
are
are
and
G.
Durand, BP107, 72003
lack
the
semiconductor
The
con-
volt-ohmmeter
distinguish
devices
A
lead
to
valid
versus
the
subject
which
involve
than
the
These
De
made
of a SeR
or
of a
is
similar
to
The
SeRs
have
100V
to
Le
Mans, France (43) 41.14.14
A
measured
is
an
measurement
devices.
on
a semiconductor
ohmmeter,
typically
corresponding
VOM
magnitude
semiconductor
blocking
characteristic
resistance
are
tested
to
meet
rated
may
shown
manufacturer's
~
------------------------- -
resistance
erroneous
semiconductor
technique
When a resistance
the
internal
1.5
or
3.0
volts,
leakage
voltage
level
of
resistance.
also
voltage/leakage
which
curve.
Semiconductor
at
the
factory
the
rated
leakage
junction
temperature.
have a range
in
Figure 1 and
rating.
TeetUmlt
value
for
segregating
measurement
is
taken
battery
and
current
determine
The
has a non-linear
current
implies a non-linear
at
rated
current
Thus,
of
resistance
still
be
with a VOM
device
with
voltage,
the device's
at
the
as
within
4400V.
The
only
valid
SeR
or
diode
resistance
indications
"short".
cathode
(0
resistance)
and
considered
resistance
normally
forward
when
Hence,
diode
high
in
both
the
An
semiconductor
of
compression
construction,
are
even
generally
on a VOM
The
anode-cathode
measurement
in
reverse
polarity)
"shorted"
for
an
shows
direction
the
VOM
the
VOM
polarity.
The
resistance
directions.
gate-cathode
open
failure
the
almost
always
if
damaged,
cannot
are
"open"
must
both
directions
for a device
and
infinite
"open". A
low
resistance
and
high
resistance
probes
are
can
be a check
SeR
normally
across
the
For a seR
must
also
on
Powerex
is a rare
bonded
event.
encapsulation
semiconductor
under
pressure,
the
electrodes
separate.
and
or
gate-
show
a short
(forward
to
be
diode
in
the
reversed.
on
has
a
anode-cathode
to
be
open,
show
open.
high
power
Because
elements
and
Figure
1.
Leakage Current vs.
Representative Semiconductor
Blocking Voltage
a
volt-
the
devices
voltage
at
the
devices
the
Precautions
1.
Determine
if the
measurement
the
device
and
the
circuit.
Open
or
gate
connection
2.
If a
disc device
make
sure
it
(approximately
reading.
appear
directions
being
Otherwise, a device
to
have
because
made
Summary
A volt-ohmmeter
technique
determining
devices.
"on-state",
parameter
is
not
acceptable
There
blocking
measurements
Westinghouse
Second
devices
to
Edition.
in a circuit, a VOM
determine
if a
catastrophically.
If
there
are
any
related
to
semiconductor
techniques,
contact
Semiconductor
assistance.
Rel
....
nce
Balenovich,
"SeR and
with a Volt
Youngwood,
Semiconductor
J.D.,
Diode
Resistance
Ohmmeter,"
PA:
Westinghouse
DMsion,
resistance
is
being
taken
not
something
an
anode,
if
in
is
being
is
under
sufficient force
200
lb.)
to get a
high
resistance
contact
intemally.
resistance
recommended
semiconductor
are
circuits
voltage,
seR
DeSigners
As a
quick
device
has
questions
measurement
your
nearest
Sales
Representative
Measurements
Westinghouse
Electric
1975.
across
else
cathode,
doubt
measured,
can
in
both
is
not
measurement
for
available
in
and
the
for
other
Handbook,
check for
will
allow
failed
or
problems
Powerex
Tech
TIp
5ยท5.
Corp.,
in
you
for
1-33
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