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LHC POWER CONVERTER

LHC POWER CONVERTER. Radiation analysis. Introduction. The aim : to use TRAD experience in spatial applications and to apply existing literature to propose test recommendation for radiation characterization compliant with LHC environment

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LHC POWER CONVERTER

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  1. LHC POWER CONVERTER Radiation analysis

  2. Introduction • The aim : to use TRAD experience in spatial applications and to apply existing literature to propose test recommendation for radiation characterization compliant with LHC environment • search of radiation tests data on the different types performed on public data base • references chosen by CERN designers : radiation data analysis & complementary radiation tests needed. • Then we propose radiation characterization recommendations and priority for the different component families : High, medium, low. • Irradiation facilities.

  3. LHC RADIATION ENVIRONMENT • Maximum radiation level for 10 years LHC operation

  4. Total Ionizing Dose • 100 Gy for 10 years : level rather low but some devices are excpected to show degradation • ELDRS has to be taken into account • Based on specifications for spatial application Margin

  5. TID Statistical approach • Delta XL = <delta x> +/- K(n,C,P) σ • There is a probability P with a confidence limit C that a given electrical parameter will not exceed the following limits Delta XL • <delta x > is the mean shift among tested population of n samples, σ is the standard deviation of the shift, K is the one sided tolerance limit factor. • A 3-sigma (K=3) approach is often used in spatial applications, with n=5 (samples) it will yield a probability of success P>0.9 with a confidence level C>0.9 • 90% of parts from a given lot have a failure level above the type TIDS, with a confidence level of 90%.

  6. Displacement Damage • Tunnel : 3 e11 1MeV neutron/cm² for 10 years • Devices concerned : Optocouplers, bipolar transistors, operational amplifiers, comparators, voltage reference,… • shielded area : 6 e10 1MeV neutron/cm2 • only a few high precision components may show a significant degradation.

  7. Single Event Effects: Thermal neutrons • 10B loacted near the sensitive nodes of the devices. • The two recoils (Li and He) ions • BPSG in CMOS devices for technology nodes of 0.15µm and older. • P+ zones doped with boron give sensitivity to thermal neutrons. • So thermal neutrons effects need to be evaluated on digital devices (FPGA, SRAM,..) • in priority : technology node >150nm. • The observed SEU sensitivity ratio is about two decades (typically 5E-14 cm2/bit with BPSG and 5E-16 cm2/bit without BPSG). • Thermal neutron effects have been studied mostly on digital devices. analog devices considered to be immune, to be checked for devices very sensitive to SET with High Energy neutrons • facilities, • ILL in Grenoble • LLB in CEA/Saclay • other reactors with a moderator to enhance the thermal/high energy ratio can also be used.

  8. Single Event Effects: High Energy Hardrons • The variation of sensitivity of the different devices to the energy of the incident hadrons is complex. • the cross-section is considered in a first approximation as constant for energy>20MeV • But for some particular effects such as SEL, SEB, MCU and ASET (Analog Single Event Transients) this assumption is probably not sufficient. • Both LET and range (related to energy) of the secondary recoils are important parameters to induce these SEEs.

  9. Heavy Ions testing approach • Heavy ions testing is proposed to obtain the LET threshold to trigger SEL. • If LETth<15 MeV*cm2/g there is a high probability that SEL will be observed with HEH. • This approach will not give the SEL cross-section for the LHC environment but will indicate if SEL tests are needed in an environment representative of the LHC environment.

  10. OP27 : bipolar technology, high precision operational amplifier • Radiation data : • Testing recommendation • OP27 operational amplifier can be used for LHC tunnel environment. • A proton test (both TID and DD) should be performed to evaluate the degradation of the most sensitive parameter Ibias.

  11. LM139 : precision voltage comparators • Radiation data : • Total dose: Input bias current drift @ 20krad • SET: cross-section and Threshold LET related to the voltage difference between inputs. • dV=12mV: sigma=4E-9 cm2 • Testing recommendation • A proton test (TID-DD) is needed to evaluate input current, gain, output current. • A high energy proton test to evaluate SET in worst case condition (Input voltage difference=10mV) should be performed

  12. UC1842 • Radiation data • No SEL @ LETth >85 MeV.cm2/mg (Warren) • TID: • Vref: 15 krad • Other parameters >50krad • ASET • Protons: Cross-section 5E-10 cm2 • Testing recommendation • UC1842 can probably be used in the application: Verify the effect of a variation of Vref, on the output voltages in the application. • TID: Vref @ H4Irrad. • ASET: protons

  13. LTC1595 16 bits DAC • Radiation data • SEL LET threshold of about 10 MeV-cm2/mg • cross section relatively small at low LETs, gradually increasing to about 10e-4 at high LET • factor of 1.5 to 2 increase in latchup cross section for the heated device. • Testing recommendation • SEL: static test • Electrical conditions: Vdd= Vddmax Vref=Vref nom. • Effects of input state on SEL sensitivity: LD, CLK, SRI will be put at 0 and then at 1. • Out1 at Gnd, • Total dose: • Bias under irradiation: Vdd nom, Vref nom :External high stable power supply , CLK (at a given frequency), 0 is stored in the register (Power On Reset), • Control: Power supply current, Output current (OUT1) • Detail test at several steps. • SET test • Room temperature test • Codes input: all0 or all1 • Observation of output with an Operational Amplifier. • Measurement of SET amplitude and duration related to switches and register bits upset.

  14. AD768 AD 16 bits DAC • Radiation data • TID : tested biased at high dose rate within specifications up to 50 krads. • SEU LETth of about 15 MeV-cm2/mg • All of these SEU occur in the standby mode. • A simple reclocking of the data reset the device. • The device was tested at constant oscillation frequencies of 0.5, 1, and 12 MHz. No SEUs were seen at these frequencies. • The device is apparently immune to SEU effects at frequencies over 0.5 MHz. • Testing recommendation • SEL test • The SEU rate is related to the refreshing frequency of the device. At high frequency (>0.5 MHz) the probability of upset can be neglected • TID and DD: The technology of AD768 is ABCMOS1 from Analog Devices. So ELDRS effects can exist. • Test to be performed at H4IRRAD in active mode. • Bias: nominal on VDD and VEE.

  15. AD7846SQ AD • Radiation data • TID • DNL exceeds specification limit at 10krads(Si). • Functional failure at 15krads(Si), recovered after 168 hour annealing., parametric degradation continues. • Devices were taken to 20krads(Si) and no functional failure was observed. After 25krads(Si), functional failures were again observed. • SEL threshold > 110 • Testing recommendation • SEL test is not mandatory because SEL was not observed with heavy ions at maximum LET. • SET: The output is a voltage output (A3 is the inside output amplifier). Output transients and outputs voltage variation will be monitored during irradiation. • Total Dose and DD • Test performed at H4IRRAD • Use of an external low noise high stability voltage reference • Parameters monitored: output voltage, power supplies Vcc, VDD, Vss current • Detailed linearity test before and after irradiation.

  16. LTC1609 16 bits ADC • Radiation data • 14 MeV neutrons • No SEL events were detected after a fluence of 2e10 neutrons per cm2. The limiting cross section 1.9 e-10 cm2 • HI • At room temperature, SEL LETth between 8.0 and 11.7 MeV-cm2/mg. • For the heated device, SEL LETth between 5.3 and 8.0 MeV-cm2/mg. • Testing recommendation • SEL to be performed at high temperature at maximum values of Vdig and Vana. • Total dose and DD: • Tests to be performed at H4IRRAD to study simultaneously DD and Total dose. • SET and SEU • Output binary code modifications to analyze for a stable input condition. • First the stability of the code values to evaluate without radiation in the facility. A window of coding is defined that take into account of all sources of noise (Example + or -2bits around the code value). Only codes outside this window are considered as SET.

  17. Tests recommendations and priorities • Discrete devices

  18. Linear devices • Mixed devices

  19. Digital devices

  20. SEE Irradiation facilites

  21. SEE Irradiation facilites

  22. SEE Irradiation facilites

  23. Conclusion • radiation characterization recommendations can be used as a guideline for the test campaign phase. • The radiation effects on the different families have been identified in WP2 and the radiation test priorities are evaluated with three criteria: high, medium, low. • All the testing recommendations, derating rules are given as a guideline and have to be used with precaution. • In some particular cases (application, very sensitive parts…) this recommendation could be not applicable and radiation testing remains the only way to characterize the part sensitivity.

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