Mauro CitterioICATPP Como – 10/4/20111 Energy Distribution in Hostile Environment: Power Converters and Devices Mauro Citterio on behalf of the INFN-APOLLO project

Mauro CitterioICATPP Como – 10/4/20112 INDEX The ATLAS LAr Calorimeter System …. a test case The Proposed Power Distribution for an Upgraded LAr System Characteristics of Power MOSFETs under irradiation - exposed to ionizing radiation (gamma 60 Co) - exposed to heavy ions ( 75 Br at 155 MeV) - exposed to protons (216 MeV) Conclusions

Mauro CitterioICATPP Como – 10/4/20113 The ATLAS experiment LAr barrel calorimeter The power distribution and conversion scheme in the detector area

Mauro CitterioICATPP Como – 10/4/20114 The required qualification doses for this application are: 4.5 x 10 4 rad and 2 x particles/cm2 (> 20 MeV) Ten times higher for Hi-LHC scenario (70 safety factor)!!! ATLAS Experiment: Lar Barrel Calorimeter Details of the Front End Electronics and Main Power Converter

Mauro CitterioICATPP Como – 10/4/20115 ATLAS Experiment: Present Status LAr Calorimeter Front-End Board (FEB) Power Distribution 19 LDO regulators/FEB

Mauro CitterioICATPP Como – 10/4/20116 CRATE 280 Vdc Main DC/DC Converter Card #3 POL LDO Converter POL LDO Converter POL LDO Converter Card #2 POL LDO Converter POL LDO Converter POL LDO Converter Card #1 POL niPOL Converter POL niPOL Converter POL niPOL Converter Regulated DC bus POL Converter with high step-down ratio Characteristics: Main isolated converter with N+1 redundancy High DC bus voltage (12V or other) Distributed Non-Isolated Point of Load Converters (niPOL) with high step-down ratio Proposed Power Supply Distribution Scheme for a LAr Upgrade MORE INFO TAKE A LOOK AT THE DEDICATED POSTER !!!

Mauro CitterioICATPP Como – 10/4/20117 The Main Converter Q1Q1 Q2Q2 Q3Q3 Q4Q4 T1T1 CoCo C4C4 L V in V ou t + - C3C3 C2C2 C1C1 T2T2 T3T3 iT2iT2 iLiL T4T V out = 12V Switched In Line Converter SILC -Required Mosfet Voltage Breakdown: ~ 200 Volt or higher -Mosfets, diodes and controller must be qualified against radiation The Point of Load S1S1 S2S2 S3S3 S4S4 L1L1 CoCo R C1C1 L2L2 UinUin UoUo + - UC1UC1 + - D<50% U o = U in D/2 POL Specifications: Input voltage: U g = 12 V Output voltage: U o = 2.5 V Output current: I o = 3A Operating frequency:f s = 1 MHz 350 nH air core inductors Critical Elements for a LAr Upgrades

Mauro CitterioICATPP Como – 10/4/20118 Power Mosfets exposed to gamma rays Devices under test: 30V STP80NF03L-04 30V LR V IRF630 Devices under test: 30V STP80NF03L-04 30V LR V IRF630 Used doses: I 1600 Gray II 3200 Gray III 5890 Gray IV 9600 Gray Used doses: I 1600 Gray II 3200 Gray III 5890 Gray IV 9600 Gray Measurements : Breakdown VGS=-10V Threshold VDS=5V ON VGS=10V Gate VDS=10V Measurements : Breakdown VGS=-10V Threshold VDS=5V ON VGS=10V Gate VDS=10V For each type of device 20 samples were tested, 5 for each dose value (tested at the ENEA Calliope Test Facility)

Mauro CitterioICATPP Como – 10/4/ V Mosfet: STP80NF03L-04

Mauro CitterioICATPP Como – 10/4/ V Mosfet: LR7843

Mauro CitterioICATPP Como – 10/4/ V Mosfet: IRF630

Mauro CitterioICATPP Como – 10/4/ Mosfet Exposed to Heavy Ions. The SEE framework Drain P + N + P _ GateSource N _ Body N + Drain P + N + P _ GateSource N _ Body N + Destructive Single Event Effects in Power MOSFETS (tested at INFN Catania) Single Event BurnoutSingle Event Gate Rupture

Mauro CitterioICATPP Como – 10/4/ The SEE experimental set-up Fast Sampling Oscilloscope Parameter Analyzer Drain P + N + P _ GateSource N _ Body N + Cg Cd 50 1 M Vgs Impacting Ion DUT Vds The current pulses The IGSS evolution during irradiation

Mauro CitterioICATPP Como – 10/4/ The SEE analysis TIME DOMAIN WAVEFORMSSCATTER PLOT MEAN CHARGE vs BIAS VOLTAGEΓ-LIKE DISTRIBUTION FUNCTION

Mauro CitterioICATPP Como – 10/4/ The SEE experimental results 200 V Mosfet: IRF630

Mauro CitterioICATPP Como – 10/4/ The SEE experimental results D21 0Gy Vds=110V Vgs=-2V

Mauro CitterioICATPP Como – 10/4/ The SEE experimental results Scatter-plot Vds=50V

Mauro CitterioICATPP Como – 10/4/ Characterization requires that an SEB circumvention method be utilized SEB characterization produces a cross-sectional area curve as a function of LET for a fixed VDS and VGS. Generally SEB is not sensitive to changes in the gate bias, VGS. However, the VGS bias shall be sufficient to bias the DUT in an off state (a few volts below V TH ), allowing for total dose effects that may reduce the V TH. Mosfet Exposed to Protons SEB characterization The only difference in the test set-up was that the current probe was on the Mosfet Source

Mauro CitterioICATPP Como – 10/4/ Mosfet Exposed to Protons The results are still preliminary. Only the 200V Mosfets (IRF 630, samples from two different manufacturers) were exposed Proton energy: 216 MeV ( facility at Massachusetts General Hospital, Boston) Ionizing Dose: < 30 Krads An absolute cross section will require the knowldege of the area of the Mosfet die which is unknown.

Mauro CitterioICATPP Como – 10/4/ The number of SEB events recorded at each VDS was small less then 30 events for the ST less than 150 events for the IR devices Large statistical errors affect the measurements The cross section at VDS = 150 V (de-rated operating voltage) can not be properly estimated Dependence from manufacturer Knee not well defined To effectively qualify the devices for 10 years of operation at Hi-LHC, the cross section has to be of the order of / cm 2, which puts the failure rate at <1 for 10 years of operation Proton irradiation campaigns with increased fluences and more samples are planned. Work still in progress …………….. Mosfet Exposed to Protons

Mauro CitterioICATPP Como – 10/4/ Distributed Power Architecture has been proposed Main converter (SILC topology) Point of load converter (IBDV topology) Critical selcction of components to proper withstand radiation Controller, Driver and Isolator FPGA for overall monitoring MOSFETS MOSFETS, both for main converter and POL have been selected and tested Gamma ray Heavy ions Protons Some results are encouraging, however more systematic validation is on-going Novel devices based on SiC and GaN, are also under investigation Conclusions