TRAD, Tests & Radiations 13/09/2011 LHC POWER CONVERTER Radiation analysis

TRAD, Tests & Radiations 2 13/09/2011Introduction  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.

TRAD, Tests & Radiations 3 13/09/2011 LHC RADIATION ENVIRONMENT  Maximum radiation level for 10 years LHC operation

TRAD, Tests & Radiations 4 13/09/2011 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

TRAD, Tests & Radiations 5 13/09/2011 TID Statistical approach  Delta XL = +/- 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  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%.

TRAD, Tests & Radiations 6 13/09/2011 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.

TRAD, Tests & Radiations 7 13/09/2011 Single Event Effects: 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.

TRAD, Tests & Radiations 8 13/09/2011 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.

TRAD, Tests & Radiations 9 13/09/2011 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.

TRAD, Tests & Radiations 10 13/09/2011 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.

TRAD, Tests & Radiations 11 13/09/2011 LM139 : precision voltage comparators  Radiation data :  Total dose: Input bias current 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

TRAD, Tests & Radiations 12 13/09/2011UC1842  Radiation data  No 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: H4Irrad.  ASET: protons

TRAD, Tests & Radiations 13 13/09/2011 LTC 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.

TRAD, Tests & Radiations 14 13/09/2011 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.

TRAD, Tests & Radiations 15 13/09/2011 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.

TRAD, Tests & Radiations 16 13/09/2011 LTC 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.

TRAD, Tests & Radiations 17 13/09/2011 Tests recommendations and priorities  Discrete devices

TRAD, Tests & Radiations 18 13/09/2011  Linear devices  Mixed devices

TRAD, Tests & Radiations 19 13/09/2011  Digital devices

TRAD, Tests & Radiations 20 13/09/2011 SEE Irradiation facilites

TRAD, Tests & Radiations 21 13/09/2011 SEE Irradiation facilites

TRAD, Tests & Radiations 22 13/09/2011 SEE Irradiation facilites

TRAD, Tests & Radiations 23 13/09/2011Conclusion  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.