an1849

Total dose testing of the ISL71090SEH precision voltage reference
Interim Report
Nick van Vonno
Intersil Corporation
Revision 0
15 August 2013
Table of Contents
1.
2.
3.
4.
5.
6.
7.
8.
Introduction and executive summary
Reference documents
Part description
Test description
4.1 Irradiation facility
4.2 Test fixturing
4.3 Characterization equipment and procedures
4.4 Experimental matrix
4.5 Downpoints
Results
4.6 Attributes data
4.7 Variables data
Discussion and conclusion
Appendices
Document revision history
1
1. Introduction and Executive Summary
This interim report discusses the results of low and high dose rate total dose testing of four versions of
the ISL71090SEH precision voltage reference. These tests were conducted to provide an assessment of the
total dose hardness of the parts and their dose rate and bias sensitivity. Samples (see Table 1) were
irradiated under bias and with all pins grounded at low dose rate and at high dose rate. The ISL71090SEH
variants are acceptance tested on a wafer by wafer basis to 100 krad(Si) at high dose rate (50 – 300
rad(Si)/s) and to 50 krad(Si) at low dose rate (0.01 rad(Si)/s), insuring hardness to the specified level for both
dose rates.
The variants of the ISL71090SEH tested include the ISL71090SEHVF12 (1.25 V nominal output), the
ISL71090SEHVF25 (2.5V nominal output voltage), the ISL71090SEHVF50 (5.0V nominal output voltage) and
the ISL71090SEHVF75 (7.5V nominal output voltage). These variants use the same base die, with the output
voltage selected by interconnect mask changes. All four variants were tested.
The ISL71090SEH variants showed good performance over low and high dose rate irradiation at this
intermediate point in the characterisation test. All samples passed the post-irradiation specifications at all
downpoints. We observed some dose rate sensitivity and bias sensitivity in the critical output voltage
parameter, see the Discussion section.
2. Reference Documents
MIL-STD-883 test method 1019.
ISL71090SEH data sheet.
Standard Microcircuit Drawing (SMD) 5962 – 13211
3: Part Description
The ISL71090SEH is a low noise precision voltage reference with a wide input voltage range from 4.0V
to 30V, with a number of output voltage options selected through interconnect metal mask changes. The
ISL71090SEH uses the Intersil PR40 bonded-wafer process, which uses dielectric isolation for important
electrical and SEE performance improvements. The part achieves sub 2μV peak to peak 0.1Hz noise with an
initial voltage accuracy of 0.05%. The ISL71090SEH offers a 2.5V output voltage option with 7ppm/°C
temperature coefficient and also provides excellent line and load regulation. The device is offered in an 8-lead
hermetic flatpack. The ISL71090SEH is ideal for high-end instrumentation, data acquisition systems and
strain and pressure sensing for space applications. Key features and specifications follow.
Features:
• DLA SMD#5962-13211
• Reference output voltage . . . . . . . . . . . . . . . . . . . . . . . . . 2.5V
• Initial accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±0.05%
• Output voltage noise . . . . . . . . . . . . . . . . . . 1.9μVP-P typical (0.1Hz to 10Hz) (2.5V option)
• Supply current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.28 mA maximum
• Tempco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10ppm/°C maximum
• Output current capability, sourcing . . . . . . . . . . . . . . . . . 20mA maximum
• Output current capability, sinking. . . . . . . . . . . . . . . . . . . 10mA maximum
• Line regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18ppm/V maximum
• Load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35ppm/mA maximum, sourcing
• Load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70ppm/mA maximum, sinking
• Operating temperature range. . . . . . . . . . . . . . . . . . . . . . .-55°C to +125°C
• Radiation environment:
- High dose rate . . . . . . . . . . . . . . . . . . . . . . .100 krad(Si)
- Low dose rate . . . . . . . . . . . . . . . . . . . . . . . 50 krad(Si)
2
- SET/SEL/SEB . . . . . . . . . . . . . . . . . . . . . . 86 MeV.cm /mg
2
4: Test Description
4.1 Irradiation Facilities
High dose rate testing was performed at an average dose rate over the total 150krad(Si) exposure of
60
67.87 rad(Si)/s using a Gammacell 220 Co irradiator located in the Palm Bay, Florida Intersil facility. Low
dose rate testing was performed at 0.01 rad(Si)/s using the Intersil Palm Bay N40 panoramic low dose rate
60
Co irradiator.
4.2 Test Fixturing
Figure 1 shows the configuration used for biased irradiation. The grounded irradiations were performed
in the same fixture type with all pins hardwired to ground.
7109X_HDR_LDR_sc
h.pdf
Figure 1: Biased irradiation configuration for the ISL71090SEH.
4.3 Characterization equipment and procedures
All electrical testing was performed outside the irradiator using the production automated test
equipment (ATE) with datalogging at each downpoint. All downpoint electrical testing was performed at room
temperature. One control unit was used to verify repeatability.
4.4 Experimental matrix
The experimental matrix is shown in Table 1. Samples of four variants of the ISL71090SEH were drawn
from preproduction PR40 lot WWH4AE and were packaged in hermetic 8-pin ceramic flatpacks (package
code KCJ). Samples were processed through the standard burnin cycle before irradiation, as required by MILSTD-883, and were screened to the ATE limits at room temperature prior to the test.
4.5 Downpoints
Downpoints to date for the low dose rate tests were zero, 25 and 50 krad(Si); the tests will be continued
to the 100 and 150krad(Si) downpoints for all four variants. The high dose rate tests are complete and the
downpoints were zero, 30, 50, 100 and 150 krad(Si).
5: Results
5.1 Attributes data
Table 1 shows the attributes data to date for the test. No rejects to the post-irradiation SMD limits were
encountered at any downpoint.
3
Table 1: ISL71090SEH total dose test attributes data as of August 2013.
Part
ISL71090SEHVF12
ISL71090SEHVF12
ISL71090SEHVF12
ISL71090SEHVF12
ISL71090SEHVF25
ISL71090SEHVF25
ISL71090SEHVF25
ISL71090SEHVF25
ISL71090SEHVF50
ISL71090SEHVF75
Dose rate,
Rad(Si)
0.01
0.01
67.8
67.8
0.01
0.01
67.8
67.8
67.8
67.8
Bias
Figure 1
Sample
size
5
Grounded 5
Figure 1
5
Grounded 5
Figure 1
5
Grounded 5
Figure 1
7
Grounded 7
Figure 1
Figure 1
5
5
Downpoint
Pre-irradiation
25 krad(Si)
50 krad(Si)
Pre-irradiation
25 krad(Si)
50 krad(Si)
Pre-irradiation
30 krad(Si)
50 krad(Si)
100 krad(Si)
150 krad(Si)
Pre-irradiation
30 krad(Si)
50 krad(Si)
100 krad(Si)
150 krad(Si)
Pre-irradiation
25 krad(Si)
50 krad(Si)
Pre-irradiation
25 krad(Si)
50 krad(Si)
Pre-irradiation
30 krad(Si)
50 krad(Si)
100 krad(Si)
150 krad(Si)
Pre-irradiation
30 krad(Si)
50 krad(Si)
100 krad(Si)
150 krad(Si)
Pre-irradiation
30 krad(Si)
50 krad(Si)
100 krad(Si)
150 krad(Si)
Pre-irradiation
30 krad(Si)
50 krad(Si)
100 krad(Si)
150 krad(Si)
Note 1: ‘Pass’ indicates a sample that passes all post-irradiation SMD limits.
4
Pass
(Note1)
5
0
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
7
7
7
7
7
7
7
7
7
7
5
5
5
5
5
5
5
5
5
5
Fail
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5.2 Variables data
The plots in Figures 2 through 14 show data at all downpoints. Figs. 2 through 6 report the response of
the ISL71090SEHVF12 samples; Figs. 7 through 12 report the results for the ISL71090SEHVF25 samples;
Fig. 13 reports the results for the ISL71090SEHVF50 (output voltage over high dose rate only); and Fig. 14
reports the results for the ISL71090SEHVF75 (output voltage over high dose rate only). The plots report the
response of all four variants to total dose irradiation at low dose rate for the biased (per Figure 1) and
unbiased (all pins grounded) cases and at high dose rate for the biased (Fig.1) and unbiased cases, with the
low dose rate data omitted for the ISL71090SEHVF50 and ISL71090SEHVF75. A final report will be issued
upon completion of the low dose rate irradiations. We chose to plot the median for these parameters due to
the relatively small sample sizes, and show the minimum and maximum values for each datapoint as well.
Section 6 will provide individual discussion of the figures.
1.2545
LDR Bias Median
LDR Bias Max
LDR GND Min
HDR Bias Median
HDR Bias Max
HDR GND Min
Spec limit
Output voltage, V
1.2535
LDR Bias Min
LDR GND Median
LDR GND Max
HDR Bias Min
HDR GND Median
HDR GND Max
Spec limit
1.2525
1.2515
1.2505
1.2495
0
50
100
150
Total dose, krad(Si)
Figure 2: ISL71090SEHVF12 output voltage as a function of total dose irradiation at low and high dose rate for
the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low dose
rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under bias,
5 at low dose rate with all pins grounded, 5 samples at high dose rate under bias and 5 samples at high dose rate
with all pins grounded. The SMD post-irradiation specification limits are 1.250122V to 1.253878V.
5
1.4
Supply current, mA
1.2
1
0.8
0.6
LDR Bias Median
LDR Bias Max
LDR GND Min
HDR Bias Median
HDR Bias Max
HDR GND Min
Spec limit
0.4
0.2
LDR Bias Min
LDR GND Median
LDR GND Max
HDR Bias Min
HDR GND Median
HDR GND Max
0
0
50
100
150
Total dose, krad(Si)
Figure 3: ISL71090SEHVF12 power supply current as a function of total dose irradiation at low and high dose
rate for the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low
dose rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under
bias, 5 at low dose rate with all pins grounded, 5 samples at high dose rate under bias and 5 samples at high
dose rate with all pins grounded. The SMD post-irradiation specification limit is 1.28mA maximum.
20
LDR Bias Median
LDR Bias Max
LDR GND Min
HDR Bias Median
HDR Bias Max
HDR GND Min
Spec limit
Line regulation, ppm/V
18
16
14
LDR Bias Min
LDR GND Median
LDR GND Max
HDR Bias Min
HDR GND Median
HDR GND Max
12
10
8
6
4
2
0
0
50
100
150
Total dose, krad(Si)
Figure 4: ISL71090SEHVF12 line regulation as a function of total dose irradiation at low and high dose rate for
the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low dose
rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under bias,
5 at low dose rate with all pins grounded, 5 samples at high dose rate under bias and 5 samples at high dose rate
with all pins grounded. The SMD post-irradiation specification limits are -18.0 ppm/V to +18.0 ppm/V.
6
Load regulation, sourcing, ppm/mA
60
50
40
30
LDR Bias Median
LDR Bias Max
LDR GND Min
HDR Bias Median
HDR Bias Max
HDR GND Min
Spec limit
20
10
LDR Bias Min
LDR GND Median
LDR GND Max
HDR Bias Min
HDR GND Median
HDR GND Max
0
0
50
100
150
Total dose, krad(Si)
Figure 5: ISL71090SEHVF12 load regulation, output sourcing 20mA, as a function of total dose irradiation at low
and high dose rate for the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01
rad(Si)/s for low dose rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low
dose rate under bias, 5 at low dose rate with all pins grounded, 5 samples at high dose rate under bias and 5
samples at high dose rate with all pins grounded. The SMD post-irradiation specification limits are -35.0 ppm/mA
to +35.0 ppm/mA.
2.5
Dropout voltage, V
2
1.5
1
LDR Bias Median
LDR Bias Max
LDR GND Min
HDR Bias Median
HDR Bias Max
HDR GND Min
Spec limit
0.5
LDR Bias Min
LDR GND Median
LDR GND Max
HDR Bias Min
HDR GND Median
HDR GND Max
0
0
50
100
150
Total dose, krad(Si)
Figure 6: ISL71090SEHVF12 dropout voltage as a function of total dose irradiation at low and high dose rate for the
biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low dose rate
irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under bias, 5 at low
dose rate with all pins grounded, 5 samples at high dose rate under bias and 5 samples at high dose rate with all pins
grounded. The post-irradiation specification limit is 2.25 V maximum.
7
2.505
HDR Bias Median
HDR Bias Max
HDR GND Min
LDR Bias Median
LDR Bias Max
LDR GND Min
Spec limit
Output voltage, V
2.503
HDR Bias Min
HDR GND Median
HDR GND Max
LDR Bias Min
LDR GND Median
LDR GND Max
Spec limit
2.501
2.499
2.497
2.495
0
50
100
150
Total dose, krad(Si)
Figure 7: ISL71090SEHVF25 output voltage as a function of total dose irradiation at low and high dose rate for
the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low dose
rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under bias,
5 at low dose rate with all pins grounded, 7 samples at high dose rate under bias and 7 samples at high dose rate
with all pins grounded. The SMD post-irradiation specification limits are 2.49625V to 2.50375V.
1.4
HDR Bias Median
HDR Bias Max
HDR GND Min
LDR Bias Median
LDR Bias Max
LDR GND Min
Spec limit
Supply current, mA
1.3
1.2
HDR Bias Min
HDR GND Median
HDR GND Max
LDR Bias Min
LDR GND Median
LDR GND Max
Spec limit
1.1
1
0.9
0.8
0.7
0.6
0
50
100
150
Total dose, krad(Si)
Figure 8: ISL71090SEHVF25 power supply current as a function of total dose irradiation at low and high dose
rate for the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low
dose rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under
bias, 5 at low dose rate with all pins grounded, 7 samples at high dose rate under bias and 7 samples at high
dose rate with all pins grounded. The SMD post-irradiation specification limit is 1.28 mA maximum.
8
20
Line regulation, ppm/V
15
10
5
0
-5
HDR Bias Median
HDR Bias Max
HDR GND Min
LDR Bias Median
LDR Bias Max
LDR GND Min
Spec limit
-10
-15
HDR Bias Min
HDR GND Median
HDR GND Max
LDR Bias Min
LDR GND Median
LDR GND Max
Spec limit
-20
0
50
100
150
Total dose, krad(Si)
Figure 9: ISL71090SEHVF25 line regulation as a function of total dose irradiation at low and high dose rate for
the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low dose
rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under bias,
5 at low dose rate with all pins grounded, 7 samples at high dose rate under bias and 7 samples at high dose rate
with all pins grounded. The post-irradiation specification limits are -18.0 ppm/V to +18.0 ppm/V.
Load regulation, sourcing, ppm/mA
40
30
20
10
0
-10
HDR Bias Median
HDR Bias Max
HDR GND Min
LDR Bias Median
LDR Bias Max
LDR GND Min
Spec limit
-20
-30
HDR Bias Min
HDR GND Median
HDR GND Max
LDR Bias Min
LDR GND Median
LDR GND Max
Spec limit
-40
0
50
100
150
Total dose, krad(Si)
Figure 10: ISL71090SEHVF25 load regulation, output sourcing 20mA, as a function of total dose irradiation at low
and high dose rate for the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01
rad(Si)/s for low dose rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low
dose rate under bias, 5 at low dose rate with all pins grounded, 7 samples at high dose rate under bias and 7
samples at high dose rate with all pins grounded. The post-irradiation specification limits are -35.0 ppm/mA to
+35.0 ppm/mA.
9
Load regulation, sinking, ppm/mA
80
HDR Bias Median
HDR Bias Max
HDR GND Min
LDR Bias Median
LDR Bias Max
LDR GND Min
Spec limit
60
40
20
HDR Bias Min
HDR GND Median
HDR GND Max
LDR Bias Min
LDR GND Median
LDR GND Max
Spec limit
0
-20
-40
-60
-80
0
50
100
150
Total dose, krad(Si)
Figure 11: ISL71090SEHVF25 load regulation, output sinking 10mA, as a function of total dose irradiation at low
and high dose rate for the biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01
rad(Si)/s for low dose rate irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low
dose rate under bias, 5 at low dose rate with all pins grounded, 7 samples at high dose rate under bias and 7
samples at high dose rate with all pins grounded. The post-irradiation specification limits are -70.0 ppm/mA to
+70.0 ppm/mA.
1.8
HDR Bias Median
HDR Bias Max
HDR GND Min
LDR Bias Median
LDR Bias Max
LDR GND Min
Spec limit
1.7
Dropout voltage, V
1.6
1.5
HDR Bias Min
HDR GND Median
HDR GND Max
LDR Bias Min
LDR GND Median
LDR GND Max
1.4
1.3
1.2
1.1
1
0.9
0.8
0
50
100
150
Total dose, krad(Si)
Figure 12: ISL71090SEHVF25 dropout voltage as a function of low and high dose rate total dose irradiation for the
biased (per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 0.01 rad(Si)/s for low dose rate
irradiation and 67.87 rad(Si)/s for high dose rate irradiation. Sample sizes were 5 at low dose rate under bias, 5 at low
dose rate with all pins grounded, 7 samples at high dose rate under bias and 7 samples at high dose rate with all pins
grounded. The post-irradiation specification limit is 1.7 V maximum.
10
5.014
HDR Bias Median
HDR Bias Min
HDR Bias Max
HDR GND Median
HDR GND Min
HDR GND Max
Spec limit
Spec limit
5.012
Output voltage, V
5.01
5.008
5.006
5.004
5.002
5
4.998
4.996
0
50
100
150
Total dose, krad(Si)
Figure 13: ISL71090SEHVF50 output voltage as a function of high dose rate total dose irradiation for the biased
(per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 67.87 rad(Si)/s, and the sample sizes
were 5 under bias and 5 with all pins grounded. The SMD post-irradiation specification limits are 4.997493V to
5.012508V.
7.515
HDR Bias Median
HDR Bias Min
HDR Bias Max
HDR GND Median
HDR GND Min
HDR GND Max
Spec limit
Spec limit
Output voltage, V
7.51
7.505
7.5
7.495
7.49
7.485
0
50
100
150
Total dose, krad(Si)
Figure 14: ISL71090SEHVF75 output voltage as a function of high dose rate total dose irradiation for the biased
(per Figure 1) and unbiased (all pins grounded) cases. The dose rate was 67.87 rad(Si)/s, and the sample sizes
were 5 under bias and 5 with all pins grounded. The SMD post-irradiation specification limits are 7.48875V to
7.51125V.
11
6: Discussion and conclusion
This document reports the results of low and high dose rate testing of four variants (1.25V, 2.5V, 5.0V
and 7.5V) of the ISL71090SEH voltage reference. Parts were irradiated under bias and with all pins grounded
at low and high dose rate in accordance with the MIL-STD-883 Test Method 1019.7 dose rate sensitivity
protocol, at 0.01 rad(Si)/s and 67.87 rad(Si)/s respectively. At the time of this interim report the low dose rate
tests have been run to 50krad(Si) and the high dose rate tests are complete through 150 krad(Si). All
parameters remained within the SMD and data sheet post-irradiation limits at all downpoints. This is a simple
part, at least functionally, and we have summarized the results in a table of attributes data (5.1, table 1)
followed by 13 curves of interest (5.2, figures 2 through 14). We will discuss each of the figures separately.
Fig. 2 shows the output voltage for the 1.25V variant. The plot shows the nominal output voltage of the
reference. The high dose rate curve shows some 0.5 mV change at 150krad(Si), while the low dose rate
curve shows 2 mV change at 50krad(Si), which is the low dose rate specification for the part. Biased
irradiation is worst case for the low dose rate test, while there is no difference between biased and unbiased
irradiation for the high dose rate test. Biased irradiation as a worst-case condition is not expected (at least in
conventional wisdom) in bipolar parts, but this behaviour was not unexpected as it has been observed on
other PR40 parts. The parameter remained well within the SMD post-irradiation limits. The data does show a
substantial difference between the high and low dose rate responses of the part, and the 1.25V variant of the
ISL71090SEH should be considered moderately low dose rate sensitive. The part is acceptance tested on a
wafer by wafer basis at high and low dose rate on a production basis, providing additional radiation hardness
assurance.
Fig. 3 shows the power supply current for the 1.25V variant. The parameter was stable at all
downpoints and showed no dose rate sensitivity or bias sensitivity. The parameter remained well within the
SMD post-irradiation limits.
Fig. 4 shows the line regulation for the 1.25V variant. The parameter was very stable at all downpoints
and showed no dose rate sensitivity or bias sensitivity. The parameter remained well within the SMD postirradiation limits.
Fig. 5 shows the load regulation for the 1.25V variant for the output sourcing 20 mA. The high dose
rate data was very stable at all downpoints and showed no dose rate sensitivity or bias sensitivity. The low
dose rate data was stable at the 25 krad(Si) downpoint but then showed an abrupt change while still
remaining well within the specification limits. The cause of this change is not known, but similar behaviour
was observed for the 2.5V variant (Figs. 10 and 11). The parameter remained well within the SMD postirradiation limits.
Fig. 6 shows the dropout voltage for the 1.25V variant. The parameter was very stable at all downpoints
and showed no dose rate sensitivity or bias sensitivity. The parameter remained well within the SMD postirradiation limits.
Fig. 7 shows the output voltage for the 2.5V variant. The plot shows the nominal output voltage of the
reference. The high dose rate curve shows some 1mV change at 150krad(Si), while the low dose rate curve
shows 3 mV change (average) at 50krad(Si), which is the low dose rate specification for the part. As in the
1.25V variant, biased irradiation is again worst case for the low dose rate test, while there is no difference
between biased and unbiased irradiation for the high dose rate test. This is an expected result as the base die
is the same for all four variants. The parameter remained well within the SMD post-irradiation limits. Also as in
the 1.25V variant, the data does show a substantial difference between the high and low dose rate responses
of the part, and the 2.5V variant of the ISL71090SEH should be considered moderately low dose rate
sensitive. The part is acceptance tested on a wafer by wafer basis at high and low dose rate on a production
basis, providing additional radiation hardness assurance.
Fig. 8 shows the power supply current for the 2.5V variant. The parameter was very stable at all
downpoints and showed no dose rate sensitivity or bias sensitivity. The parameter remained well within the
SMD post-irradiation limits.
12
Fig. 9 shows the line regulation for the 2.5V variant. The parameter was very stable at all downpoints
and showed no dose rate sensitivity or bias sensitivity. The parameter remained well within the SMD postirradiation limits.
Figs. 10 and 11 show the load regulation for the 2.5V variant for two cases: the output sourcing 20 mA
and the output sinking 10mA, respectively. The high dose rate data was very stable at all downpoints and
showed no dose rate sensitivity or bias sensitivity. The low dose rate data for both conditions was stable at
the 25 krad(Si) downpoint but then showed an abrupt change while still remaining well within the specification
limits. The cause of this change is not known, but similar behaviour was observed for the 1.25V variant (Fig.
5). The parameter remained well within the SMD post-irradiation limits.
Fig. 12 shows the dropout voltage for the 2.5V variant. The parameter was very stable at all downpoints
and showed no dose rate sensitivity or bias sensitivity. The parameter remained well within the SMD postirradiation limits.
The next two figures show the results of high dose rate testing only and plot the output voltage only for
the 5.0 and 7.5V variants. The other parameters for these two variants showed equal stability to that shown
by the 1.25 and 2.5V variants, and the low dose rate results apply due to the use of the same base die.
Complete low and high dose rate results will be presented in the final report.
Fig. 13 shows the output voltage for the 5.0V variant, in this case for high dose rate only. The plot
shows the nominal output voltage of the reference. The high dose rate curve shows some 4mV change at
150krad(Si). As in the 1.25V and 2.5V variants high dose rate results there was no difference between biased
and unbiased irradiation. As this variant uses the same base die as the 1.25 and 2.5V variants, this part
should be considered moderately low dose rate sensitive. The part is acceptance tested on a wafer by wafer
basis at high and low dose rate on a production basis, providing additional radiation hardness assurance.
Finally Fig. 14 shows the output voltage for the 7.5V variant, again for high dose rate only. The plot
shows the nominal output voltage of the reference. The high dose rate curve shows some 5mV change at
150krad(Si). As in the 1.25V and 2.5V variants high dose rate results there was no difference between biased
and unbiased irradiation. As this variant uses the same base die as the 1.25 and 2.5V variants, this part
should be considered moderately low dose rate sensitive. The part is acceptance tested on a wafer by wafer
basis at high and low dose rate on a production basis, providing additional radiation hardness assurance.
All four variants of the ISL71090SEH showed good performance over low and high dose rate irradiation
at this intermediate point in the characterisation test. All samples passed the post-irradiation at all downpoints.
The part is acceptance tested on a wafer by wafer basis to 100 krad(Si) at high dose rate (50 – 300 rad(Si)/s)
and to 50 krad(Si) at low dose rate (0.01 rad(Si)/s), insuring hardness to the SMD-specified level for both
dose rates. The output voltage data does show a substantial difference between the high and low dose rate
responses of the part, and the ISL71090SEH should be considered moderately low dose rate sensitive. This
change in the output voltage is believed to be caused by radiation-induced change in the bandgap voltage,
which provides the basic reference for the part. The output voltage also showed biased irradiation to be worst
case, which represents an interesting change from conventional radiation testing wisdom but has been seen
before for this process. No measurable differences in the total dose response were noted between biased and
grounded irradiation for the other parameters.
This is an interim report, and a final version is expected to be released following the 150 krad(Si) low
dose rate testing. This is expected to occur in Quarter 2 of 2014.
13
7: Appendices
7.1: Reported parameters and their post-irradiation limits:
Fig.
2
3
4
5
6
7
8
9
10
11
12
13
14
Parameter
Output voltage, 1.25V variant
Power supply current, 1.25V variant
Line regulation, 1.25V variant
Load regulation, sourcing, 1.25V variant
Dropout voltage, 1.25V variant
Output voltage, 2.5V variant
Power supply current, 2.5V variant
Line regulation, 2.5V variant
Load regulation, sourcing, 2.5V variant
Load regulation, sinking, 2.5V variant
Dropout voltage, 2.5V variant
Output voltage, 5.0V variant
Output voltage, 7.5V variant
Limit, low
1.250122
2.49625
4.997493
7.48875
Limit, high
1.253878
1.28
18.0
35.0
2.25
2.50375
1.28
18.0
35.0
70.0
1.7
5.012508
7.51125
8: Document revision history
Revision
0
Date
15 August 2013
Pages
All
Comments
Original issue
14
Units
V
mA
ppm/V
ppm/mA
V
V
mA
ppm/V
ppm/mA
ppm/mA
V
V
V
Notes
+ 20.0 mA
+ 20.0 mA
- 10.0 mA
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