1. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 1 Changes since PDR Spacecraft Selection and Meetings: –PDU was moved to opposite side of SIU to match SC power/C&DH physical partitioning –Signal levels (discretes, 1 PPS, Science Interface, GBM GRB signal) were officially changed to LVDS (before undefined or RS422), March 03 –Recently finalized power, analog monitoring, and discrete interface to SC –Defined MIL1553 command set/interface –Separated SIU prime and redundant into separate (and identical) crate assemblies since cross-connection to SC prime and redundant was solved on the SC- LAT interface level and lead to removal of direct SIU-SIU inter- connections Before SC selection After SC selection COMMENT- Add Major to title & choose 1 chart

2. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 2 Changes since PDR (Con’t) Event-Builder was moved from CPU crates to GAS unit –Reduced complexity of inter-connections –Reduced hardware from 3 event-builder blocks to 2 (1 prime, 1 redundant), and power dissipation from two event-builder blocks to one SIU crate was modified to be the same as EPU crate –Removes mechanical, thermal, electrical design effort for one assembly –Moved SC science interface from Spacecraft Interface Board in SIU to event-builder in GASU –Additional benefit that SIB board is almost identical to existing SECCI version (both boards are designed by NRL/Silver Engineering), major simplification –Science interface on GASU is small change since GASU already transmits event data to LAT CPU’s, so additional target is incremental –Added SIB board in each EPU crate to provide local EEPROM Simplification in software effort. No remote booting code development/testing required.

3. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 3 LAT Electronics Physical 16 Tower Electronics Modules –DAQ electronics module (DAQ-EM) –Power-supplies for tower electronics * Primary & Secondary Units shown in one chassis 3 Event-Processor Units (2+1 spare) –Event processing CPU –LAT Communication Board –SIB Spacecraft Interface Unit –Spacecraft Interface Board (SIB): Spacecraft interface for MIL1553 control & data –LAT control CPU –LAT Communication Board (LCB): LAT command and data interface Power-Distribution Unit (PDU)* –Spacecraft interface, power –LAT power distribution –LAT health monitoring Global-Trigger/ACD-EM/Signal-Distribution Unit* TKR CAL TKR Front-End Electronics (MCM) ACD Front-End Electronics (FREE) CAL Front-End Electronics (AFEE)

4. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 4 Optimization – Summary Serial LVDS (Low-Voltage-Differential-Swing) protocol with Data, Clock, Reset, Return-Data to each front-end system and between DAQ modules (see LAT-TD-00606) Buffering of event data fragments at each module stage to meet dead-time requirements –TKR front-end -> TEM -> Event-Builder -> LAT Communication Board -> CPU -> Spacecraft Solid-State Recorder Flow-control between buffer stages to meet non-overwriting and data consistency requirements Utilization of ASIC’s to meet volume, power, and cost constraints COMMENT- DELETE THIS PAGE

5. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 5 Heritage Similar data-acquisition system was used on balloon flight (TEM, one event-processing CPU, one spacecraft-interface- equivalent control CPU) Electronics components: mostly components with flight- heritage (FPGA’s, LVDS converters, memories) ASIC technology same as for tracker, calorimeter, ACD systems Trigger, dataflow, event assembly, and event filter processing very similar to past high-energy physics experiments COMMENT- DELETE THIS PAGE

6. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 6 LAT Spacecraft Interface Power –28V regulated and unregulated MIL1553 –Commanding Science Interface (LVDS) –Transport of science data to spacecraft solid-state recorder 1-PPS timing signal (LVDS) –Timing pulse GBM GRB Candidate signal (LVDS) –Notification of candidate Gamma-Ray Burst (GRB), from GBM routed through SC Discretes (LVDS) –Pulsed and level digital signals from and to spacecraft Analog Monitoring –Temperature and voltage monitoring by SC without having LAT powered Two power/signal sets: Prime and redundant All agreed to: Spectrum Astro SC-LAT Interface Document LVDS: Low-Voltage-Differential-Swing signaling

7. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 7 Power Interface to Spacecraft All power feeds from spacecraft can be turned off/on via ground Spacecraft turns off SIU/DAQ feeds when going to survival mode LAT start-up ICD: LAT- TD-01536 –Describes process of cold and warm boot (bring-up) of LAT

8. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 8 Spacecraft 1-PPS and GRB Candidate Signal 1-PPS signal from spacecraft prime and redundant are connected to both GASU DAQ boards (prime and redundant) GASU DAQ selects which SC signal to use Result is fanned out to all processor crates (SIU’s as well as EPU’s) Crate DAQ selects which GASU signal to use SC-LAT components are fully cross-connected Same for GBM GRB candidate signal

9. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 9 Spacecraft Discrete Signal Discrete Signals from SC to LAT: –Discrete LVDS-signals from spacecraft prime and redundant are connected to both SIU crates (prime and redundant) –Reset discrete: P and R SC signal is logically Or’ed and used as CPU reset –Spare discretes: CPU selects whether to use P or R input and result is routed to CPU discrete inputs (3 prime and 3 redundant) Discrete Signals from LAT to SC (not shown) –Discrete LVDS-signals from LAT SIU P and SIU R are driven to both, prime and redundant, spacecraft C&DH (Control & Data Handling) systems

10. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 10 LAT-SC Science Interface GASU event builder –Directs data from TEM’s to any of the CPU’s (not shown) –Directs data from CPU to CPU –Directs data from CPU to spacecraft Any CPU can direct data via either GASU DAQ (P or R) to SC Data is driven to both SC sections (P and R) –SC needs to select which GASU to listen to –GASU needs to know from which SC (P or R) the flow-control line is valid –All configured via ground commanding

11. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 11 Power Interface to Spacecraft All power feeds from spacecraft can be turned off/on via ground Heaters are on separate power feeds Each SIU is powered via one dedicated SC power feed Rest of LAT power is on main feed –One primary, one redundant Cross-connected in LAT PDU –Can use either SC main feed to power either PDU

12. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 12 Power Allocation QuantityColdCurrent Hot Case CaseEstimateAllocation Total286.20313.79318.00359.85 Mech On-Board Power1 38.00 35.0038.00 TEM--Tower Electronics Module 43.20 46.7048.00 54.32 TEM board16 2.70 2.923.00 3.39 Power Supplies 148.50 163.29165.00 186.72 TKR,CAL,TEM16 9.28 10.21 11.67 GASU--Global Tgr ACD, Signal Dist. Unit 19.80 22.3722.00 24.90 EP, AEM, Sig Dist & Supplies1 22.37 Other Boxes 74.7081.4383.0093.92 SIU--Spacecraft Interface Unit1 21.60 23.8924.00 27.16 EPU Total 38.70 42.6043.00 48.66 EPU--Event Processor Unit2 19.35 21.3021.50 24.33 PDU--Power Distribution Unit1 14.40 14.9316.00 18.11

13. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 13 Grounding & Shielding LAT RF SHIELD BOX ENCLOSURE

14. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 14 EMI/ EMC & EMI Allocation Primary document 433-RQMT-005 Radiated Emissions (RE101, RE102) –20% of total emissions are allocated to subsystems outside LAT RF shield ACD, Tracker, Heaters –60% of total emissions are allocated to subsystems inside LAT shield Radiated Susceptibility (RS101,RS103) –All subsystems must meet Section 5.3 of 433-RQMT-005 Conducted Emissions (CE101, CECM) –Only the T&DF subsystem is affected and must meet requirements Conducted Susceptibility (CS101, CS116) –Only the T&DF subsystem is affected and must meet requirements COMMENT- Radiation Hardness?

15. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 15 Connections LAT/Spacecraft and to LAT EMI Shield (focus)

16. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 16 Example: Connections LAT/Spacecraft and to LAT EMI Shield

17. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 17 SHIELDING

18. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 18 Monitoring & Thermal Control Outline Overview Temperature Monitoring (Matrix) Voltage/Current Monitoring (Matrix) Operating Temperature Control Survival Summary

19. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 19 Monitoring Spacecraft monitors –Voltages & Temperatures PDU SIU GASU VCHP switches –Temperatures Locations outside LAT EMI shield PDU monitors –Voltages & Temperatures TEM EPU SIU –Temperatures Locations outside LAT EMI shield GASU monitors –Voltages & Temperatures ACD TEM monitors –Voltages & Temperatures CAL TKR

20. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 20 Temperature Monitoring (SC & PDU) NameTypeSpacecraftPDU PrimeRedundantPrime Redundan t ACD TilesThermal55 ACD TSA Shell (inside)Thermal55 ACD TSA Shell (outside)Thermal 22 ACD BEA-Grid interfaceThermal 22 ACD PMT RailThermal4444 Calorimeter BaseplateThermal 16 SIUThermal22 PDUThermal22 EPUThermal 33 GASUThermal22 TEM DAQ BoardThermal 16 TEM pwr SupplyThermal 16 Radiator Anti-Freeze HtrThermal 44 RadiatorsThermal8810 Grid-Radiator interfaceThermal4444 Grid Make-up HeatersThermal44 VCHP-XLHP interfaceThermal4412 X-LAT PlateThermal44 VCHP-DSHP interfaceThermal 12 GridThermal 12 VCHP's Reservoir HtrThermal12 24 VCHP Reservoir Htr Pri/SecVoltage44 Spare Temp. ChannelsThermal88

21. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 21 Temperature Monitoring (TEM & GASU) NameTypeTEMGASU PrimeRedundant ACD FREEThermal 12 CAL AFEEThermal128 AEM Power SupplyThermal 11 AEM DAQ BoardThermal 11 TKR CablesThermal256 LAT Instrumentation Plan: LAT-SS-00890 Spacecraft ICD: GSFC-IRD-433

22. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 22 Voltage/Current Monitoring NameTypeSpacecraftPDUTEMGASU PrimeRedundantPrimeRedundant VCHP Reservoir Htr Pri/SecVoltage44 SIU Pri/Sec 3.3/5V VVoltage22 PDU Pri/Sec 3.3V VVoltage22 GASU Pri/Sec 3.3/28V/3.3VA VVoltage22 66 EPU 3.3V VVoltage 44 TEM 3.3V VVoltage 16 ACD FREE VVoltage 12 ACD FREE ICurrent 11 ACD HV (I)Current 24 TKR VVoltage 64 TKR ICurrent 64 CAL VVoltage 48 CAL ICurrent 48 TEM DAQ VVoltage 16 TEM DAQ ICurrent 16 LAT SIU Bus V Pri/SecVoltage22 LAT VCHP Bus V Pri/SecVoltage22 Spare Voltage ChannelsVoltage18 Total 32 20 25643

23. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 23 Heater Control Survival Heaters (GRID & VCHP Anti-Freeze) –Powered by SC unregulated feed –Block redundant prime and redundant set –Thermostat control, not controlled by LAT electronics Survival & Operational Heaters (VCHP) –Powered by SC regulated feed –Block redundant prime and redundant set of 12 heaters –Controlled by LAT SIU Temperature monitoring Software algorithm in CPU 12 hardware switches in SIB Hardware watchdog to power heaters as default –Final responsibility of survival is by SC LAT-SS-00715 Thermal Control System ICD

24. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 24 Instrument Protection Instrument Damage Protection Against LAT Hardware & Software Malfunction –Protection against high and low temperatures –Protection of ACD Photo-Multiplier Tubes (PMT’s) in South- Atlantic Anomaly (SAA) –Document: LAT-TD-01553

25. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 25 High and Low Temperatures GRID/Anti-freeze heaters –turn on when T is below thermostats –no LAT active control VCHP heaters –LAT responsible for operational control Survival –if T too high or too low SC puts LAT into safe mode Turns-off LAT SIU and Main DAQ power

26. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 26 ACD PMT Protection LAT turns down PMT high-voltage levels during SAA passage to protect PMT’s –SC SAA notification PMT’s are hardware protected within ACD in case of DAQ mishap –ACD HV supplies have built-in protection to limit current to PMT’s

27. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 27 Summary Monitoring of temperatures, voltages, and currents defined Heater control defined Instrument protection tree documented –LAT DAQ does not have final responsibility to protect instrument from damage Responsibility of spacecraft

28. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 28 Tracker Electronics TKR sub-system electronics Si-Strip Detectors 24 GTFE (GLAST Tracker Front-End) ASIC (1,536 signal channels) 2 GTRC (GLAST Tracker Readout Controller) ASIC MCM (Multi-Chip Module) Flex-cables Presented in tracker sub-system CDR GTFE ASIC GTRC ASIC

29. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 29 Calorimeter Electronics CAL sub-system electronics Diodes 48 GCFE (GLAST Calorimeter Front-End) ASIC 4 GCRC (GLAST Calorimeter Readout Controller) ASIC AFEE (Analog Front-End Electronics) board Presented in calorimeter sub-system CDR GCFE ASIC GCRC ASIC

30. GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 30 ACD Electronics ACD sub-system electronics PMT’s 18 GAFE (GLAST ACD Front-End) ASIC 1 GARC (GLAST ACD Readout Controller) ASIC FREE (Front-End Electronics) board High-Voltage Supply board (not shown) Presented in ACD sub-system CDR GAFE ASIC GARC ASIC