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PSI tests - Comparator Results

PSI tests - Comparator Results. Devices under test and beam conditions Schematics Results Input bias current Output drift I-V acquisition of the comparator outputs Gain Response time SET. Devices under test and beam conditions. DUT LM339D, LP339M and LM139 : SET LM339D and LP339M

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PSI tests - Comparator Results

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  1. PSI tests - Comparator Results • Devices under test and beam conditions • Schematics • Results • Input bias current • Output drift • I-V acquisition of the comparator outputs • Gain • Response time • SET

  2. Devices under test and beam conditions • DUT • LM339D, LP339M and LM139: • SET • LM339D and LP339M • Input biasmeasurements • LM339D: • Output drift • I-V acquisition of the comparator outputs • Gain • Response time • Beam conditions: • PIF facility at PSI • Proton energy was set to 230 MeV • Dose rate : 7.5 rad/s (270 Gy/h)

  3. Schematics SET evaluation • From literature, the lowest ΔVin gives the highest chance to get SETs

  4. Schematics Input bias current

  5. Schematics Output drift / Response time / Gain / I-V measurements • 4 kinds of measurements performed: • Output drift by applying a constant V(-) during irradiation • During test breaks: • Gain by applying a saw tooth at V(-) • Response time by supplying V(-) with a square wave • I-V curves by using a Source Measure Unit (Keithley)

  6. Input Bias Current • LM339D • Vin > 0 • V(-) = 7.5V • I(+) = 75 nA → V(+) = 7.5 V • 1st Run • Up to 80 Gy • At 80 Gy run was stopped • Change supply voltage from: • +/- 15V to 0/34V

  7. Input Bias Current • 2nd Run • Vin > 0 • V(-) = 17V • I(+) = 170 nA → V(+) = 17 V • At ≈ 155 Gy → I(+)max is exceeded (250 nA)

  8. Input Bias Current • LP339M • At ≈ 57 Gy → I(+)max is exceeded (25 nA)

  9. Output Drift • Voutinit set to –Vcc (-15V) • Test break : • Othermeasurements (Gain etc…) • Trend of the Vout variation vs dose: • Vout tends to lower values • From 0 to 300Gy: • Voutdriftedfrom: • -14.927 V to -14.895 V (32 mV) • LM339D • Can be assumed as very small • Datasheet affords no information concerning the allowed drift

  10. I-V measurements of the comparator outputs • LM339D • Test break : • I-V measurements • Source-Measure Unit (Keithley) • Inject I and measureVout

  11. I-V measurements of the comparator outputs • A trend of the output is observable: • I-V curves → Lower values of Ic vs Dose • LM339D Breakdown • Reasons: • β (output transistor) decreased • Current source isdamaged Active field of the transistor

  12. Gain • Test break : • V(-) → SawtoothwaveformΔV = 10mV • V(+) → Ground

  13. Gain • Specifications: • Gainmin = 50V/mV • Gain of the 2 irradiatedcomparatorsdecrease vs dose • Variation of the reference Gainis due to the limitedresolution of the scope to measure Vin. • The increase of Vin is due to the input offset • As dose increases, ΔVin increases to change the output state • → Lowresolutionisless dominant • Switching voltage increases with dose.

  14. Response time • A step from -100mV to +100mV was applied on V(-). • Results show that response time increases vs dose with respect to the reference: • Rising time can be acceptable depending on the application • 50% after a TID of 150 Gy (from 2.1 µs to 3 µs) • 220% after a TID of 300Gy (from 2.1 µs to 4.75 µs)

  15. Summary of the Results • The analysed parameters show a degradation. In some cases the datasheet limit is exceeded

  16. Conclusions • No SET (>15 ns and > 100 mV) have been observed for any of the DUTs. • The analysed parameters show a degradation • In some cases the datasheet limit is exceeded as shown in the previous table • The degradation can be tolerated depending on the application

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