Energy Distribution in Hostile Environment: Power Converters and Devices

1. Energy Distribution in Hostile Environment: Power Converters and Devices Mauro Citterioon behalf of the INFN-APOLLO project

2. 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 60Co) • - exposed to heavy ions (75Br at 155 MeV) • - exposed to protons (216 MeV) • Conclusions

3. The ATLAS experiment LAr barrel calorimeter The power distribution and conversion scheme in the detector area

4. ATLAS Experiment: Lar Barrel Calorimeter Details of the Front End Electronics and Main Power Converter The required qualification doses for this application are: 4.5 x 104 rad and 2 x 1012 particles/cm2 (> 20 MeV)  Ten times higher for Hi-LHC scenario (70 safety factor)!!!

5. ATLAS Experiment: Present Status LAr Calorimeter Front-End Board (FEB) Power Distribution 19 LDO regulators/FEB

6. Main DC/DC Converter LDO Converter LDO Converter LDO Converter niPOL Converter LDO Converter LDO Converter LDO Converter niPOL Converter niPOL Converter POL POL POL POL POL POL POL POL POL Proposed Power Supply Distribution Scheme for a LAr Upgrade MORE INFO  TAKE A LOOK AT THE DEDICATED POSTER !!! CRATE Card #2 Card #3 Card #1 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 POL Converter with high step-down ratio 280 Vdc Regulated DC bus

7. + C4 Q4 L T1 + iL + Vout T3 Q3 Co C3 - Vin + C2 Q2 T4 iT2 T2 + Q1 C1 Vout = 12V S1 S2 L1 + + S4 Uin Uo Co R UC1 C1 - - L2 S3 D<50% Uo = UinD/2 Critical Elements for a LAr Upgrades The Main Converter The Point of Load • POL Specifications: • Input voltage: Ug= 12 V • Output voltage: Uo = 2.5 V • Output current: Io = 3A • Operating frequency: fs = 1 MHz • 350 nH air core inductors • Switched In Line Converter SILC • Required Mosfet Voltage Breakdown: ~ 200 Volt or higher • Mosfets, diodes and controller must be qualified against radiation

8. Power Mosfets exposed to gamma rays Devices under test: 30V STP80NF03L-04 30V LR7843 200V IRF630 For each type of device 20 samples were tested, 5 for each dose value (tested at the ENEA Calliope Test Facility) Measurements : BreakdownVoltage @ VGS=-10V Threshold Voltage @ VDS=5V ON Characteristic @ VGS=10V GateLeakage @ VDS=10V Useddoses: I 1600 Gray II 3200 Gray III 5890 Gray IV 9600 Gray

9. 30 V Mosfet: STP80NF03L-04

10. 30 V Mosfet: LR7843

11. 200 V Mosfet: IRF630

12. Source Source Gate Gate Body Body _ _ + + N N P P + + P P _ _ N N + + N N Drain Drain Mosfet Exposed to Heavy Ions.The SEE framework Destructive Single Event Effects in Power MOSFETS (tested at INFN Catania) Single EventBurnout Single EventGateRupture

13. The IGSS evolution during irradiation Source Gate Vgs Vds 1 MW 1 MW Body Cd 50 W + N _ P DUT The current pulses Cg Impacting Ion 50 W + P _ N + N Drain The SEE experimental set-up Parameter Analyzer Fast Sampling Oscilloscope

14. The SEE analysis TIME DOMAIN WAVEFORMS SCATTER PLOT NUMERICAL INTEGRATION Γ-LIKE DISTRIBUTION FUNCTION PARAMETERS EXTRACTION MEAN CHARGE vs BIAS VOLTAGE Γ-LIKE DISTRIBUTION FUNCTION

15. The SEE experimentalresults 200 V Mosfet: IRF630 The increaseof the ϒ-dose causesa reduction of the critical bias condition at which drain and gate damages appear

16. The SEE experimental results D21 0Gy Vds=110V Vgs=-2V Twodifferent sensitive areas D21 0Gy Vds=110V Vgs=-2V Meancharge vs Vds The SEB currentpulse

17. The SEE experimental results Scatter-plot Vds=50V The increaseof the ϒ-dose causes a wideningof the currentpulses

18. Mosfet Exposed to Protons SEB characterization 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 VTH), allowing for total dose effects that may reduce the VTH. The only difference in the test set-up was that the current probe was on the Mosfet Source

19. 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.

20. 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 10-17/ cm2, which puts the failure rate at <1 for 10 years of operation Proton irradiation campaigns with increased fluencesand more samples are planned. Mosfet Exposed to Protons Work still in progress ……………..

21. 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