Test Report 006 Neutron Testing of the ISL78845ASEH Pulse Width Modulator Introduction This report summarizes results of 1MeV equivalent neutron testing of the ISL78845ASEH current mode PWM controller. The test was conducted in order to determine the sensitivity of the part to the Displacement Damage (DD) caused by the neutron environment. Neutron fluences ranged from 2x1011n/cm2 to 1x1014n/cm2. This project was carried out in collaboration with Honeywell Aerospace (Clearwater, FL), and their support is gratefully acknowledged. Part Description The ISL78845ASEH is a high performance, radiation hardened drop-in replacement for the popular 28C4x and 18C4x PWM controllers and is suitable for a wide range of power conversion applications including boost, flyback and isolated output configurations. Its fast signal propagation and output switching characteristics make this an ideal product for existing and new designs. Features include up to 13.2V operation, low operating current, 90µA typical start-up current, adjustable operating frequency to 1MHz, and high peak current drive capability with 50ns rise and fall times. There are four variants of this part: the ISL78840SEH with rising Undervoltage Lockout (UVLO) threshold of 7V and 100% maximum duty cycle, the ISL78841SEH with rising UVLO threshold of 7V and 50% maximum duty cycle, the ISL78843SEH with rising UVLO threshold of 8.4V and 100% maximum duty cycle and finally the ISL78845ASEH with rising UVLO threshold of 8.4V and 50% maximum duty cycle. The four variants are closely similar and the ISL78845ASEH data discussed in this report is considered applicable to the other three variants. The ISL78845ASEH is available in an 8 Ld hermetic ceramic flatpack and in die form and offers guaranteed performance across the full -55°C to +125°C military temperature range. Characterization equipment and procedures Electrical testing was performed before and after irradiation using the Intersil production Automated Test Equipment (ATE). All electrical testing was performed at room temperature. Experimental matrix Testing proceeded in general accordance with the guidelines of MIL-STD-883 Test Method 1017. The experimental matrix consisted of six samples irradiated at 2.2x1011 n/cm2, six samples irradiated at 4.4x1011n/cm2, six samples irradiated at 6.6x1011n/cm2, three samples irradiated at 1x1012n/cm2, three samples irradiated at 1x1013n/cm2 and five samples irradiated at 1x1014 n/cm2. Two control units were used to insure repeatability. Samples were taken from current production inventory. Results Test results Neutron testing of the ISL78845ASEH is complete and the results are reported in the balance of this report. It should be realized when reviewing the data that each neutron irradiation was made on a different 6- or 3-unit sample; this is not total dose testing, where the damage is cumulative. Variables data The plots in Figures 1 through 20 show data plots for key parameters before and after irradiation to each level. The plots show the median, minimum and maximum of each parameter for each of the four amplifier channels as a function of neutron irradiation. We chose to plot the median because of the small sample sizes involved. We also show the applicable electrical limits taken from the SMD, this for guidance only as the ISL78845ASEH is not specified for neutron irradiation. Test Description Irradiation Facilities Neutron irradiation was performed by the Honeywell team at the Fast Burst Reactor facility at White Sands Missile Range (White Sands, NM), which provides a controlled 1MeV equivalent neutron flux. Parts were tested in an unbiased configuration with all leads shorted together. As neutron irradiation activates many of the elements found in a packaged integrated circuit, the parts exposed at the higher neutron levels required (as expected) significant ‘cooldown’ time before being shipped back to Intersil (Palm Bay, FL) for electrical testing. May 12, 2015 TR006.0 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2015. All Rights Reserved Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. Test Report 006 9.1 SPEC HIGH UVLO START VOLTAGE (V) 8.9 8.7 MEDIAN 8.5 MIN MAX 8.3 8.1 SPEC LOW 7.9 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 1. ISL78845ASEH Undervoltage Lockout (UVLO) START threshold voltage as a function of neutron irradiation, showing the median, minimum and maximum of the populations following irradiation to each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011 n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). For reference, the SMD limits are 8V to 9V. (21) 8.1 SPEC HIGH 8.0 7.9 UVLO STOP VOLTAGE (V) MIN MAX 7.8 MEDIAN 7.7 7.6 7.5 7.4 7.3 SPEC LOW 7.2 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 2. ISL78845ASEH UVLO STOP threshold voltage as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011 n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). For reference, the SMD limits are 7.3V to 8V. (22) Submit Document Feedback 2 TR006.0 May 12, 2015 Test Report 006 600 SPEC HIGH STARTUP CURRENT (µA) 500 400 300 200 MAX MEDIAN 100 MIN 0 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 3. ISL78845ASEH startup current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2 x 1011 n/cm2 (6 samples), 4.4 x 1011 n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). For reference, the post-irradiation SMD limit is 500µA. 4.5 SPEC HIGH 4.0 OPERATING CURRENT (mA) 3.5 3.0 MEDIAN MAX 2.5 2.0 MIN 1.5 1.0 0.5 0 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 4. ISL78845ASEH operating current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011 n/cm2 (6 samples), 4.4x1011 n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1 x 1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014 n/cm2 (3 samples). The SMD limit is 4mA maximum. Submit Document Feedback 3 TR006.0 May 12, 2015 Test Report 006 6 SPEC HIGH OPERATING SUPPLY CURRENT (mA) 5 4 MEDIAN MAX 3 2 MIN 1 0 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 5. ISL78845ASEH operating supply current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4 x 1011 n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1 x 1014 n/cm2 (3 samples). The SMD limit is 5.5mA maximum. 5.06 SPEC HIGH 5.04 REFERENCE VOLTAGE (V) 5.02 5.00 MEDIAN 4.98 MIN 4.96 MAX 4.94 SPEC LOW 4.92 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 6. ISL78845ASEH reference voltage accuracy as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are 4.925V to 5.050V. Submit Document Feedback 4 TR006.0 May 12, 2015 Test Report 006 0 VREF CURRENT LIMIT, SOURCING (mA) -10 SPEC HIGH -20 -30 -40 -50 MEDIAN MAX -60 MIN -70 1E+11 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 7. ISL78845ASEH reference current limit, sourcing, as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limit is -20mA minimum. 30 MEDIAN MAX VREF CURRENT LIMIT, SINKING (mA) 25 MIN 20 15 10 5 SPEC LOW 0 1E+11 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 8. ISL78845ASEH reference current limit, sinking, as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limit is 5mA minimum. Submit Document Feedback 5 TR006.0 May 12, 2015 Test Report 006 1.5 SPEC HIGH CURRENT SENSE BIAS CURRENT (µA) 1.0 0.5 MAX 0 MEDIAN MIN -0.5 -1.0 -1.5 Pre-rad SPEC LOW 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 9. ISL78845ASEH current sense input bias current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011 n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are -1µA to 1µA. 1.04 SPEC HIGH 1.03 MAXIMUM INPUT SIGNAL (V) 1.02 MEDIAN MIN 1.01 MAX 1.00 0.99 0.98 SPEC LOW 0.97 0.96 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 10. ISL78845ASEH current sense maximum input signal as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1 x 1014 n/cm2 (3 samples). The SMD limits are 0.97V to 1.03V. Submit Document Feedback 6 TR006.0 May 12, 2015 Test Report 006 3.6 SPEC HIGH 3.4 CS GAIN (V/V) 3.2 3.0 MEDIAN MAX 2.8 MIN 2.6 SPEC LOW 2.4 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 11. ISL78845ASEH current sense gain (ACS = VCOMP / VCS) as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012 n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are 2.5V/V to 3.5V/V. Two out of three samples were nonfunctional after irradiation to 1x1014n/cm2. 2.54 SPEC HIGH 2.53 EA REFERENCE VOLTAGE (V) 2.52 MIN MAX MEDIAN 2.51 2.50 2.49 2.48 SPEC LOW 2.47 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 12. ISL78845ASEH error amplifier reference as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012 n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are 2.475V to 2.530V. Submit Document Feedback 7 TR006.0 May 12, 2015 Test Report 006 1.5 SPEC HIGH FEEDBACK INPUT BIAS CURRENT (µA) 1.0 0.5 MAX MEDIAN 0 -0.5 MIN SPEC LOW -1.0 -1.5 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 13. ISL78845ASEH error amplifier input bias current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are -1µA to 1µA. 12 COMPARATOR SINK CURRENT (mA) 10 MIN 8 MAX MEDIAN 6 4 2 SPEC LOW 0 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE, (n/cm2) FIGURE 14. ISL78845ASEH error amplifier sink current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limit is 1mA minimum. Submit Document Feedback 8 TR006.0 May 12, 2015 Test Report 006 0 -0.1 COMPARATOR SOURCE CURRENT (mA) -0.2 -0.3 SPEC HIGH -0.4 -0.5 MAX MEDIAN -0.6 MIN -0.7 -0.8 -0.9 -1.0 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 15. ISL78845ASEH error amplifier source current as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limit is -0.4mA minimum. 5.10 SPEC HIGH 5.05 MIN COMPARATOR VOH (V) 5.00 MAX MEDIAN 4.95 4.90 4.85 SPEC LOW 4.80 4.75 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 16. ISL78845ASEH error amplifier HIGH output voltage as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are 4.80V to 5.050V. Submit Document Feedback 9 TR006.0 May 12, 2015 Test Report 006 1.2 SPEC HIGH 1.0 MEDIAN COMPARATOR VOL (V) MAX 0.8 MIN 0.6 SPEC LOW 0.4 0.2 0 Pre-rad 1.E+12 1.E+13 1.E+14 NEUTRON FLUENCE (n/cm2) FIGURE 17. ISL78845ASEH error amplifier LOW output voltage as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limits are 0.4V to 1V. 54 SPEC HIGH 53 MAX MEDIAN FREQUENCY (kHz) 52 MIN 51 50 49 SPEC LOW 48 47 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 18. ISL78845ASEH oscillator frequency as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014 n/cm2 (3 samples). The SMD limits are 48kHz to 53kHz. Submit Document Feedback 10 TR006.0 May 12, 2015 Test Report 006 70 SPEC HIGH CURRENT SENSE TO OUTPUT DELAY (ns) 60 50 MIN 40 MAX MEDIAN 30 20 10 0 1E+12 Pre-rad 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 19. ISL78845ASEH current sense to output delay as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limit is 60ns maximum. 50.5 50.0 MAXIMUM DUTY CYCLE (%) 49.5 49.0 48.5 MEDIAN MAX 48.0 47.5 MIN SPEC LOW 47.0 46.5 Pre-rad 1E+12 1E+13 1E+14 NEUTRON FLUENCE (n/cm2) FIGURE 20. ISL78845ASEH maximum duty cycle as a function of neutron irradiation, showing the median, minimum and maximum of the populations at each level. Neutron fluences and sample sizes (in parentheses) were 2.2x1011n/cm2 (6 samples), 4.4x1011n/cm2 (6 samples), 6.6x1011n/cm2 (6 samples), 1x1012n/cm2 (3 samples), 1x1013n/cm2 (3 samples) and 1x1014n/cm2 (3 samples). The SMD limit is 47% minimum. Submit Document Feedback 11 TR006.0 May 12, 2015 Test Report 006 Discussion and conclusion This document reports the results of neutron testing of the ISL78845ASEH current mode PWM controller. Samples were irradiated to levels of 2.2x1011n/cm2, 4.4x1011n/cm2, 6.6x1011n/cm2, 1x1012n/cm2, 1x1013n/cm2 and 1x1014n/cm2, with sample sizes of six each for the first three cells and three each for the last three cells. It should again be carefully realized when interpreting the attributes and variables data that each neutron irradiation was performed on a different sample; this is not total dose testing, where a single set of samples is used and the damage is cumulative. ATE characterization testing was performed before and after the irradiations, and two control units were used to insure repeatable data. Variables data for monitored parameters is presented in Figures 1 through 20. The current sense maximum input signal (Figure 10) showed some degradation at the highest two neutron levels but remained well within the SMD limits. The current sense gain (Figure 11) showed good stability at the lower levels but was nonfunctional after 1x1014n/cm2, with two of the three samples failing this test. The error amplifier reference voltage (Figure 12) showed good stability after all neutron levels. The error amplifier input bias current and sink current (Figures 13 and 14) showed good stability to the 1x1013n/cm2 level but decreased significantly after 1x1014n/cm2. Both parameters remained within the SMD limits. The error amplifier source current (Figure 15) showed good stability after all neutron levels. The ISL78845ASEH is not formally designed for neutron hardness. The part is built in a junction-isolated submicron BiCMOS process; the bipolar transistors are minority carrier devices, obviously, and may be expected to be sensitive to Displacement Damage (DD) at the higher neutron levels. This expectation turned out to be correct. We will discuss the results on a parameter by parameter basis and then draw some conclusions. The error amplifier HIGH and LOW output voltages (Figures 16 and 17) showed good stability to the 1x1013n/cm2 level with slight decreases after 1x1014n/cm2. The Undervoltage Lockout (UVLO) START and STOP threshold voltages (Figures 1 and 2) showed good stability after all neutron levels. The current sense to output delay (Figure 19) showed good stability after all neutron levels. The startup current, operating current and operating supply current (Figures 3 through 5) showed excellent stability after all neutron levels. The reference voltage accuracy (Figure 6) showed good stability after all neutron levels, with a gradually decreasing range at the higher levels. The reference sourcing and sinking current limits (Figures 7 and 8) showed excellent stability after all neutron levels. The oscillator frequency (Figure 18) showed good stability to the 1x1013n/cm2 level but decreased significantly after 1x1014n/cm2. The parameter remained well within the SMD limits. The maximum duty cycle (Figure 20) showed good stability after all neutron levels. We conclude that the ISL78845ASEH is capable of post 1x1013n/cm2 operation (likely with some relaxation of parametric specifications for some parameters) within the SMD post-total dose parameters. The part is not capable of post 1x1014n/cm2 operation as it was nonfunctional, failing the current sense gain parameter. The current sense input bias current (Figure 9) showed good stability to the 1x1013n/cm2 level but decreased significantly after 1x1014n/cm2. The parameter was near the lower SMD limit after 1x1014n/cm2. Submit Document Feedback 12 TR006.0 May 12, 2015 Test Report 006 Appendices TABLE 1. REPORTED PARAMETERS FIGURE PARAMETER LIMIT, LOW LIMIT, HIGH UNIT 1 UVLO START Threshold Voltage 8 9 V 2 UVLO STOP Threshold Voltage 7.3 8 V 3 Startup Current - 500 µA 4 Operating Current - 4 mA 5 Operating Supply Current - 5.5 mA 6 Reference Voltage Accuracy 4.925 5.050 V 7 Reference Current Limit, Sourcing -20 - mA 8 Reference Current Limit, Sinking 5 - mA 9 Current Sense Input Bias Current -1 1 µA 10 Current Sense Maximum Input Signal 0.97 1.03 V 11 Current Sense Gain 2.5 3.5 V/V 12 Error Amplifier Reference Voltage 2.475 2.530 V 13 Error Amplifier Input Bias Current -1 1 µA 14 Error Amplifier Sink Current 1 - mA 15 Error Amplifier Source Current -0.4 - mA 16 Error Amplifier HIGH Output Voltage 4.80 5.05 V 17 Error Amplifier LOW Output Voltage 0.4 1 V 18 Oscillator Frequency 48 53 kHz 19 Current Sense To Output Delay - 60 ns 20 Maximum Duty Cycle 47 - % Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the document is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com Submit Document Feedback 13 TR006.0 May 12, 2015