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IXR100
6
the effects of non-uniform fields existing in heterogeneous
dielectric material during barrier degradation. In the case of
void non-uniformities, electric field stress begins to ionize
the void region before bridging the entire high voltage
barrier.
The transient conduction of charge during and after the
ionization can be detected externally as a burst of
0.01
μ
s-0.1
μ
s current pulses that repeat on each AC voltage
cycle. The minimum AC barrier voltage that initiates partial
discharge is defined as the “inception voltage”. Decreasing
the barrier voltage to a lower level is required before partial
discharge ceases and is defined as the “extinction voltage”.
We have designed and characterized the package to yield an
inception voltage in excess of 2400Vrms so that transient
overvoltages below this level will not cause any damage.
The extinction voltage is above 1500Vrms so that even
overvoltage-induced partial discharge will cease once the
barrier voltage is reduced to the rated level. Older high
voltage test methods relied on applying a large enough
overvoltage (above rating) to catastrophically break down
marginal parts, but not so high as to damage good ones. Our
new partial discharge testing gives us more confidence in
barrier reliability than breakdown/no breakdown criteria.
APPLYING THE IXR100
The IXR100 has been designed primarily to correct
nonlinearities inherent in RTD sensors. It may also be used
in other applications where its excellent performance makes
it superior to other devices available. Examples are shown in
the Applications Section.
potentiometer connected as shown in Figures 2a and 2b. The
circuit shown in Figure 2a provides more range while the
circuit in Figure 2b provides better resolution. Note, it is not
recommended to use this adjusting procedure for zero eleva-
tion or suppression. See the signal suppression and elevation
section for the proper techniques.
COM
This is the return for the two excitation currents I
REF1
and
I
REF2
and is the reference point for the inputs.
V
S
, I
OUT
These are the connections for the current loop V
S
being the
most positive connection. For correct operation these pins
should have 11.6 to 36V between them.
HIGH VOLTAGE TESTING
Burr-Brown Corporation has adopted a partial discharge test
criterion that conforms to the German VDE0884 Optocoupler
Standards. This method requires the measurement of minute
current pulses (< 5pC) while applying 2400rms, 60Hz high-
voltage stress across every devices isolation barrier. No
partial discharge may be initiated to pass this test. This
criterion confirms transient overvoltage (1.6
x
V
RATED
)
protection without damage. Life-test results verify the ab-
sence of failure under continuous rated voltage and maxi-
mum temperature.
This new test method represents the “state-of-the-art” for
nondestructive high voltage reliability testing. It is based on
FIGURE 3. Transient and RFI Protection Circuit.
4
1
3
2
C
1
+
–
IXR100
5
0.4mA
TRANZORB
R
1
R
Z
RTD
NOTE: (1) R and R should be made equal if used (±1% resistors are adequate).
0.01μF
3.9k
R
2
C
BYPASS
C
BYPASS
Optional Input
Filtering
(1)
(1)
= Transmitter Case
0.4mA
7
6
S
9
8
LIN
R
R
1N4148
C
BYPASS
28
18
R
L
–
+
V
OUT
V
S