SIU Manufacturing Readiness Review (MRR)

1. Gamma-ray Large Area Space Telescope SIU Manufacturing Readiness Review (MRR) GLAST Large Area Telescope: G. Haller SLAC haller@slac.stanford.edu (650) 926-4257

2. Contents • Overview (G. Haller) • SIU Module Description • Changes since CDR • Design and Test Documentation • Engineering Module Validation • Production • Quality Assurance Quality Assurance Plan

3. LAT Electronics TKR Front-End Electronics (MCM) ACD Front-End Electronics (FREE) TKR CAL Front-End Electronics (AFEE) 16 Tower Electronics Modules & Tower Power Supplies CAL Global-Trigger/ACD-EM/Signal-Distribution Unit* 3 Event-Processor Units (EPU) (2 + 1 spare) • Event processing CPU • LAT Communication Board • SIB Spacecraft Interface Units (SIU)* • Storage Interface Board (SIB): Spacecraft interface, control & telemetry • 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 * Primary & Secondary Units shown in one chassis

4. SIU/EPU Mounted on LAT SIU EPU’s PDU

5. SIU/EPU Crate Electronics • Storage Interface Board (SIB) • EEPROM • MIL1553 Communication with spacecraft* • Power Control of PDU/GASU power switches in PDU* • Power Control of VCHP switches in heater box* • LAT Communication Board (LCB) • Communication with GASU • Commanding • Read-back Data • Housekeeping Data • Event Data • Crate Power Supply Board (CPS) • 28V to 3.3V/5V conversion • Power-On Reset • LVDS-CMOS conversion of spacecraft discretes* • System clock to GASU • CPU Board (RAD750) • Processor** • IO of level-converted SC discretes • Crate Backplane (CBP) • passive • *Only used in SIU crate • **Start-up ROM code different from EPU and SIU

6. SIU/EPU Crate • Partially loaded crate on left (without LCB and SIB) • Fully loaded crate on right • Shown are also serial card and ethernet cards, not part of flight assembly (cards with front-panel connections)

7. CBP & CPS & CPU CBP (Crate Backplane) CPS (Crate Power Supply Board) CPU (RAD750 from BAE)

8. SIB & LCB SIB (Storage Interface Board) LCB (LAT Communication Board)

9. Changes since CDR • SIB/LCB • Code in FPGA was finished/modified and bugs fixed • Some resistor values were changed to optimize performance • CPS • Some resistor/capacitor values were changed to optimize performance • Backplane • Some interconnections were added between modules and connector IO

10. Power Peer Review RFA Status • RFA 3 • Request • Need to get AR-461 filter schematic plus schematic of 28-28 supply on spacecraft.  Need to develop model of power and ground distribution to verifiy filter performance relative to 100 kHz noise.  Damping of the entire filter network should also be verified to assure that an interactive among the many identical filters cannot occur. • Response (SLAC) • The PRU Road Show exercised the Spacecraft PRU and the LAT interface and tested the performance. The results are: • (1) The interface between the Spacecraft and LAT is understood (pinouts and signal definitions) . • (2) The SIU, VCHP and DAQ feeds are stable under full load. • (3) The conducted EMI is within the requirement. • (4) The Calorimeter - Tracker mini-tower performs properly with the spacecraft PRU. • (5) There were no significant transients when the LAT feed is turned off when fully powered . • The test results are documented in LAT-AM-04670.

11. Power Peer Review RFA Status (Continued) • RFA 4 • Request • T0-220 Maxim regulators have their mounting tabs connected to ground.  This has the potential of creating an undesirable ground path with associated noise problems.  The optimum grounding solution for this particular configuration is to connect all elements to chassis and use the structure as the primary ground return (as diagrammed on the conference room whiteboard).  It is strongly recommended that this approach be taken to assure proper instrument performance despite the fact that the approach is slightly unorthodox.  As a second issue, it is also suggested that gold foil or indium foil be used to assure reproducible heat sink contact for the regulators.  The grease or no intermediate material approaches are strongly recommended against. • Response (SLAC) • 1) The grounding approach defined in the RFA is the current implementation. The grounding tabs on the Maxim regulators are mounted directly to the enclosure, and the enclosure used as the primary ground return • (2) The regulators are mounted using a thermally conductive adhesive (CV-2946 Nusil). Tests on the EM hardware showed minimal temperature rise (a few degrees) across the interface.

12. Power Peer Review RFA Status (Continued) • RFA 5 • Request • Maxim part screening must be carefully done to assure that the testing provides valid verification reliability.  Documented methods by Maxim are for static burn-in only (diffusion based issues) and do not represent the actual operational case planned for GLAST.  In that the GLAST application is actually fairly stressful AND uses the part outside of its normal operational range (for the 1.5 volt output case), it is suggested that the screening and qual test be configured to verify the 1.5 volt configuration since it is most stressful.  Note that great care must be taken with the layout and instrumentation to assure that the setup does not accidentally result in part damage. • Response (NASA/SLAC) • Parts were screened and qualification testing performed at GSFC.

13. Power Peer Review RFA Status (Continued) • RFA 6 • Request • The 28 volt converter planned for use by Spectrum Astro, uses a step-up transformer.  A quick calculation indicates that the step-up ratio is probably 1.5 or more.  therefore, a failure where the control loop goes open while the bus is at 33 volts, could put as much as 50 volts on the input to the power supply regulators.  Such a condition could have catastrophic consequences to the instrument such that system level redundancy could be compromised due to progagation of the failure across interfaces.  Therefore, it is strongly recommended that overvoltage protection be implemented to assure protection of the hardware plus protection against failure propagation. • Response (NASA) • Lambda identified a credible single point failure that could cause an overvoltage condition.  Spectrum added a transorb across the output of each 28 volt feed to prevent the voltage from exceeding 38 V.  A test was run at Lambda at the end of August to verify the design.  The preliminary results show that the voltage never exceeded 38 V.  Spectrum Astro is reviewing the test results and performing additional studies to ensure the test results are analytically consistent with the circuitry.

14. ELX Peer Review RFA Status • RFA 23 • Request • In order to understand EMI, perform SPICE analysis of the LAT internal power distribution bus. Include models for S/C DC/DC converters, all filters, and LAT DC/DC converters. Use model to establish EMI self-compatibility, i.e. will the internal EMI sources cause problems. Look at inrush issues as well • Response • We are not able to perform SPICE level simulations due to the lack of SPICE models for the converter hybrids. However no issues were found in tests performed (PRU road-show and test-bed). EMI will be tested on the qualification models.

15. ELX Peer Review RFA Status (Continued) • RFA 24 • Request • For the CDR, revise the grounding scheme chart to make it more clear and accurate. • Response • Was done for CDR

16. SIU/EPU Documents (all released) • SIB • LAT-DS-01674-56 Circuit Card Assembly SIU-SIB • LAT-DS-02871-51 PWB, Fab, Loading, and Assembly-SIU-SIB • LAT-TD-02585-54 Excel Bill of Materials SIU-SIB • LAT-DS-01675-51 Printed-Wiring Board SIB • LAT-DS-02141-51 6u-Front-Panel • LAT-DS-02403-50 Heat-Sink Stiffener • LAT-DS-01676-51 Storage Interface Board Schematic • LCB • LAT-DS-01679-56 Circuit Card Assembly • LAT-DS-01680-51 Printed-Wiring Board LCB • LAT-DS-02872-51 PWB, Fab, Loading, and Assembly • LAT-TD-02584-53 Bill of Materials • LAT-DS-02141-51 6u-Front-Panel • LAT-DS-02403-50 Heat-Sink Stiffener • LAT-DS-01681-54 LCB Schematic • CPS • LAT-DS-01669-56 Circuit Card Assembly • LAT-DS-01670-53 Printed-Wiring Board CPS • LAT-DS-02870-53 PWB, Fab, Loading, and Assembly • LAT-TD-02356-54 Bill of Materials • LAT-DS-02140-51 3u-Front-Panel • LAT-DS-02401-50 Heat-Sink • LAT-DS-01702-54 Crate Power Supply Schematic • CBP • LAT-DS-01662-52 Circuit Card Assembly • LAT-DS-01663-52 Printed-Wiring Board CPB 4-25-05 • LAT-DS-02869-52 PWB, Fab, Loading, and Assembly • LAT-TD-02586-50 Bill of Materials in excel • LAT-DS-02964-56 Assembly: CBP, cable and connector plate • LAT-DS-02117-50 Connector Plate, SIU/EPU Chassis • SIU/EPU Assembly • LAT-DS-01862-52 SIU/EPU Assembly

17. Engineering Model Design Validation • Tested on bench and on test-bed • Functionality and performance validated on test-bed • 16 TEM/TPS, EM PDU and GASU connected to SIU & EPU’s • Validated over frequency and voltage margins • Limitations • Only limited temperature tests performed on SIU

18. Parts, Materials, and Processes • All EEE Parts approved by the Program Parts Board • Materials • All Materials have been approved by the Program MPRB in accordance with LAT-SS-00107, LAT Mechanical Parts Plan • GLAST/LAT Material Usage Agreement #002 (MAR DID No. 313; LAT Document # LAT-TD-04756-01)- Approved 9/13/04 • Processes • All processes have been reviewed and approved by the Program MPRB in accordance with LAT-SS-00107, LAT Mechanical Parts Plan

19. Procurement Status • All parts were procured and received • FPGA’s were programmed • Contract for assembly was awarded • Manufacturing Process Flow at assembler, Configuration Management, identical to what was presented for the PDU & GASU, see • http://www-glast.slac.stanford.edu/Elec_DAQ/Reviews/GASU-MRR/reviews.htm

20. Quality Assurance • Same vendor and processes as used for PDu and GASU modules • See QA presentation at • http://www-glast.slac.stanford.edu/Elec_DAQ/Reviews/GASU-MRR/reviews.htm