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GLAST LAT Project
SIU MRR
GLAST Large Area Telescope:
SIU Manufacturing
Readiness Review (MRR)
Gamma-ray Large
Area Space
Telescope
G. Haller
SLAC
[email protected]
(650) 926-4257
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SIU MRR
Contents
• Overview (G. Haller)
– SIU Module Description
– Changes since CDR
– Design and Test Documentation
– Engineering Module Validation
• Production
• Quality Assurance Quality Assurance Plan
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LAT Electronics
ACD
TKR Front-End Electronics (MCM)
ACD Front-End Electronics (FREE)
CAL Front-End Electronics (AFEE)
TKR
16 Tower Electronics Modules & Tower
Power Supplies
CAL
Global-Trigger/ACD-EM/Signal-Distribution Unit*
Spacecraft Interface
Units (SIU)*
– Storage Interface
Board (SIB):
Spacecraft interface,
control & telemetry
– LAT control CPU
– LAT Communication
Board (LCB): LAT
command and data
interface
EPU-1
3 Event-Processor Units (EPU) (2 + 1
spare)
– Event processing CPU
– LAT Communication Board
– SIB
EPU-2
Power Dist. Unit*
empty
empty
GASU*
empty
empty
empty
SIU*
SIU*
EPU-3
Power-Distribution Unit (PDU)*
– Spacecraft interface,
power
– LAT power distribution
– LAT health monitoring
* Primary & Secondary Units shown in one chassis
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SIU/EPU Mounted on LAT
SIU
EPU’s
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PDU
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GLAST LAT Project
SIU MRR
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
•
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VCHP
Heater Box
BackPlane
SIB
Heater
Control*
Power
Control*
PDU
PCI
Interface
EEPROM
Spacecraft
MIL1553
MIL1553*
LCB
CommandResponse
GASU
PCI
Interface
FIFO
Event Data
GASU
Spacecraft
Discretes
CPS
LVDS Convertion
Spacecraft
Power
28-V DC/
DC
Power-On
Reset
GASU
3.3V/5V
System
Clock
CPU
Discrete I/O
PCI
Interface
Power PC
*Only used in SIU crate
**Start-up ROM code different from EPU and SIU
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GLAST LAT Project
SIU MRR
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)
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CBP & CPS & CPU
CBP (Crate Backplane)
CPS (Crate Power Supply Board)
CPU (RAD750 from BAE)
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SIB & LCB
SIB (Storage Interface Board)
LCB (LAT Communication Board)
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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
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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.
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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 (CV2946 Nusil). Tests on the EM hardware showed minimal temperature rise (a
few degrees) across the interface.
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SIU MRR
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.
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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.
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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.
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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
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SIU/EPU Documents (all released)
•
•
•
•
•
SIB
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–
–
–
–
–
LCB
–
–
–
–
–
–
–
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
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
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–
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–
–
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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
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–
–
–
–
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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
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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
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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-TD04756-01)- Approved 9/13/04
Processes
–
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All processes have been reviewed and approved by the Program MPRB in accordance with LAT-SS00107, LAT Mechanical Parts Plan
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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
–
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http://www-glast.slac.stanford.edu/Elec_DAQ/Reviews/GASU-MRR/reviews.htm
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Quality Assurance
• Same vendor and processes as used for PDu and GASU
modules
• See QA presentation at
–
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http://www-glast.slac.stanford.edu/Elec_DAQ/Reviews/GASU-MRR/reviews.htm
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