GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 1 Changes since PDR...

GLAST LAT Project CDR/CD3 May 12-15, 2003

G. Haller 4.1.7 Elec LAT Design 1

Changes since PDRChanges 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



Changes since PDR (Con’t)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.

SIU

EventBuilder

GlobalTrigger

CommandResponse

Unit

TEM 0

CAL

TKR

TEM 1

CAL

TKR

TEM 15

CAL

TKR

ACD

ACD

ACD

ACD ElectronicsModule

GAS Unit

EPU 0 EPU 1

SCCommanding

SC ScienceData

0 1 11



LAT Electronics PhysicalLAT Electronics Physical

16 Tower Electronics Modules– DAQ electronics module (DAQ-EM)– Power-supplies for tower electronics

* Primary & Secondary Units shown in one chassis

ACD

spare

EPU-3

EPU-2EPU-1

spare spare

Pwr Dist. Box

GASU

spare

spare

SIU-P SIU-R

3 Event-Processor Units (2+1 spare)

– Event processing CPU– LAT Communication Board– SIBSpacecraft 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)



Optimization – SummaryOptimization – 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



HeritageHeritage

• 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



LAT Spacecraft InterfaceLAT Spacecraft Interface

Power

SPACECRAFT

MIL1553

LAT

1 PPS

GBM GRBCandidate

DiscretesDigital

Analogs

Science Data

• 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



Power Interface to SpacecraftPower Interface to Spacecraft

toUnregulatedVoltagePrimary

to

to

to

GRID or Anti-Freeze

Heaters,several

zones, eachzone has itsown set of

thermostats/heaters

VCHPsurvival/

operationalheaters

RegulatedVCHP Voltage

Primary

Turn on control fromSIU P and SIU R


Redundant

Prime

Prime

Redundant

RegulatedSIU-Prime

Voltage

SIUPrime

Regulated SIU-Redundant

Voltage

SIURedundant

Regulated MainDAQ Prime

Voltage

PDUPrime

Regulated MainDAQ Redundant

Voltage

PDURedundant

Spacecraft LAT

To other thermostats/heater zones


to

to

to

Redundant


Turn on control fromSIU P and SIU Rl

Cross-connected:either PDU

can useeither feed

All switches arecontrolled by

spacecraft

Power to restof LAT

To other switches(12 total)


• 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



Spacecraft 1-PPS and GRB Candidate SignalSpacecraft 1-PPS and GRB Candidate Signal

S1S2

D

C

ENB

Multiplexer

1-PPS P

1-PPS RS1S2

D

C

ENB

Multiplexer

GASU DAQ BoardRedundant

GASU DAQ Board Prime

S1S2

D

C

ENB

MultiplexerFan-Out

E.g SIU P

Spacecraft LAT

To other crates

• 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



Spacecraft Discrete SignalSpacecraft Discrete Signal

Discretes P

Discretes R

SIU Crate Redundant

SIU Crate Prime

CPU

Spacecraft LAT

• 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



LAT-SC Science InterfaceLAT-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

Receiver P

Receiver R

GASU DAQ BoardRedundant

GASU DAQ Board Prime

Switch

SIU P

Spacecraft LAT

S1S2

D

C

ENB

Multiplexer

S1S2

D

C

ENB

Multiplexer

To other LAT CPU’s

To other LAT CPU’s

EPU R

2 SIU’s,3 EPU’s



Power Interface to SpacecraftPower Interface to Spacecraft


to

to

to

GRID or Anti-Freeze

Heaters,several

zones, eachzone has itsown set of

thermostats/heaters

VCHPsurvival/

operationalheaters


Primary

Turn on control fromSIU P and SIU R


Redundant

Prime

Prime

Redundant

RegulatedSIU-Prime

Voltage

SIUPrime

Regulated SIU-Redundant

Voltage

SIURedundant

Regulated MainDAQ Prime

Voltage

PDUPrime

Regulated MainDAQ Redundant

Voltage

PDURedundant

Spacecraft LAT



to

to

to

Redundant


Turn on control fromSIU P and SIU Rl

Cross-connected:either PDU

can useeither feed

All switches arecontrolled by

spacecraft

Power to restof LAT



• 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



Power AllocationPower Allocation

Quantity Cold Current Current Hot Case

Case Estimate Allocation

Total 286.20 313.79 318.00 359.85

Mech On-Board Power 1 38.00 35.00 38.00 38.00

TEM--Tower Electronics Module 43.20 46.70 48.00 54.32

TEM board 16 2.70 2.92 3.00 3.39

Power Supplies 148.50 163.29 165.00 186.72

TKR,CAL,TEM 16 9.28 10.21 11.67

GASU--Global Tgr ACD, Signal Dist. Unit 19.80 22.37 22.00 24.90

EP, AEM, Sig Dist & Supplies 1 22.37

Other Boxes 74.70 81.43 83.00 93.92

SIU--Spacecraft Interface Unit 1 21.60 23.89 24.00 27.16

EPU Total 38.70 42.60 43.00 48.66

EPU--Event Processor Unit 2 19.35 21.30 21.50 24.33

PDU--Power Distribution Unit 1 14.40 14.93 16.00 18.11



Grounding & ShieldingGrounding & Shielding

FILTER FILTER

TKR/CAL_FE

ACD_FEFILTER

ACD ASSY

FILTER

TEM ASSY.

EPU

FILTER

FILTER

FILTER

POWER ASSY.

DIST-GLT ASSY. SPACECRAFT

T

28 VOLTS

MIL-1553

SSR

HSKP

GRID COMMON

SPACECRAFT

SUBSYSTEM

GROUND

COMMON

SIU

FILTER

BONDINGSTRAP

( ONE PLACE )

FILTERFILTER

OUTER SHIELDGRID CABLE

LAT RF SHIELD

BOX ENCLOSURE



EMI/ EMC & EMI AllocationEMI/ 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?



Connections LAT/Spacecraft and to LAT EMI Connections LAT/Spacecraft and to LAT EMI Shield (focus)Shield (focus)



Example: Connections LAT/Spacecraft and to Example: Connections LAT/Spacecraft and to LAT EMI ShieldLAT EMI Shield

+Y

Ra

dia

tor

Bra

cke

t-Y

Ra

dia

tor

Bra

cke

t

ACDElectronics

Box(x 24)

SIURdnt

SIUPrim

PDUBox

SC PRUPrim2.8A

regulated

+Y HeaterControl Box

JL-126

-Y HeaterControl Box

JL-139

SC PRURdnt2.8 A

regulated

JL-1

13

JL-1

12

JL-146

SC PDUPrim

unregulated

SC PDURdnt

unregulated

12 c + 6 gnd

12 c + 6 gnd

12 c + 6 gnd

12 c + 6 gnd

JL-1

07

JL-3

JL-4

JL-1

JL-2

4 pr tm +4 pr vm

JL-34

4 pr pwr +4 pr vm

4 pr pwr +4 pr vm

4 pr pwr

4 pr pwr

JL-141

6 -Y VCHP Heater Rdnt

6 -Y VCHP Heater Prim2 -Y Rad Antifreeze Heater Prim

2 -Y Grid Make Up Heater Rdnt

2 -Y Grid Make Up Heater Prim

2 -Y Rad Antifreeze Heater RdntJL-143

JL-147

JL-150

4 pr pwr

4 pr pwr

4 pr pwr

12 pr pwr

4 pr pwr

4 pr pwr

4 pr pwr12 pr pwr

48 pr tm

Grid (12 tm)Cal baseplate (16 tm)

JL-105 JL-37

JL-106

JL-149

2 pr pwr (AWG18)

2 pr pwr (AWG18)

2 pr pwr (AWG18)

JL-33JL-31

4 pr pwr

4 pr pwr

2 pr vm

2 pr tm

1 pr mil1553

1 pr mil1553

12 pr discrete

12 pr discrete

1 pr mil1553

1 pr mil1553

12 pr discrete

12 pr discrete

SCC&DHPrim

SCC&DHRdnt

SC AnalogMonitor Rdnt

SC AnalogMonitor Prim

4 pr pwr

4 pr pwr

12 pr pwr

12 pr pwr

XLAT plateJL

-12

3

JL-142

JL-140

JL-144

[ FROM ACD TO SC ]ACD Tiles (10 tm)ACD PMT Rail (8 tm)ACD Shell (10 tm)

2 pr pwr + 2 pr vm (-Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)

2 pr pwr + 2 pr vm (-Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)

2 pr pwr + 2 pr vm (+Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)

2 pr pwr + 2 pr vm (+Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)

4 pr tm

4 pr tm

32 pr tm

16 pr tm

16 pr tm

32 pr tm

16 pr tm

16 pr tm

2 pr pwr (AWG18)

-Y VCHP-XLHP Intf (4 tm)

Grid (12 tm)Cal baseplate (16 tm)

Timing Prim/Rdnt

GRBM Prim/Rdnt

JL-1

10

JL-1

09

GASUBox

JL-5

JL-7

JL-8

JL-4

4JL

-45

JL-4

1JL

-40 16 pr LATP +

8 pr pwr +2 pr tm + 2 pr vm

16 pr LATP +8 pr pwr +

2 pr tm + 2 pr vm

-Y VCHP Heaters (24 tm)-Y VCHP-XLHP Intf (12 tm)-Y VCHP-DSHP Intf (12 tm)

48 pr tm

SC PRUPrim25A

regulated

SC PRURdnt25A

regulated

16 pr pwr

16 pr pwr

4 pr tm + 4 pr vm

4 pr tm + 4 pr vm

(2 pr tm + 2 pr vm, pdu Prim & rdnt) + (2 pr tm + 2 pr vm, gasu Prim & rdnt)

(2 pr tm + 2 pr vm, pdu Prim & rdnt) + (2 pr tm + 2 pr vm, gasu Prim & rdnt)

16 pr pwr

4 pr tm +4 pr vm

16 pr pwr

4 pr vm

4 pr vm

28 pr tm

28 pr tm

JL-9,10,11

JL-13 … 28

JL-6

JL-1

08

8 pr tm

(8 c)*2 + 8 gnd

(8 c)*2 + 8 gnd

EPUBox(x 3)

TEMBox

(x 16)

JL-7

0,7

1,7

2

x 3

4 pr pwr + 2 pr tm + 2 pr vm

x 16

JL-8

9-1

04

4 pr pwr + 4 pr tm + 2 pr vm

JL-6

6,6

7,6

8

JL-46,47,48

JL-50 … 65

JL-7

3-8

8

x 3

x 16

100

51

JL-1

17

JL-230

JL-1

16

JL-1

19

JL-232

JL-1

22

JL-1

20

100

100

EPUBox

(test only)JL-1

55

JL-1

54

6 +Y VCHP Heater Rdnt

6 +Y VCHP Heater Prim

+Y Grid Rad Intf (4 tm)2 +Y Grid Make Up Heater (4 tm)+Y Radiator (8 tm)

[ FROM ACD TO PDU ]ACD BEA-Grid Intf (4 tm)ACD PMT Rail (8 tm)ACD Shell (4 tm)

Grid Rad Intf (8 tm)Radiator (20 tm)Radiator Antifreeze Heaters (8 tm)

JL-12

4 pr pwr +2 pr tm +2 pr vm

JL-49

100JL-29

JL-43JL-42

22 pr science +2 pr 1PPS +2 pr GRBM 22 pr science +

2 pr 1PPS +2 pr GRBM

JL-125



JL-1

24

11 pr science

11 pr science

11 pr science

11 pr science

NOTE: ONLY FIXED POSITION CONNECTORS ARESHOWN. CABLE CONNECTORS ARE NOT SHOWN.SC CONNECTORS NOT SHOWN. ACD NOT SHOWN.

JL-1

11

JL-1

14

JL-130

JL-131

JL-127

JL-129

JL-137JL-136

JL-134JL-133

2 +Y Rad Antifreeze Heater Prim

2 +Y Rad Antifreeze Heater Rdnt

2 +Y Grid Make Up Heater Prim

32 pr tm

JL-128

2 +Y Grid Make Up Heater Rdnt

AC

D T

em

pS

en

sor

Bra

cke

t

+Y VCHP Heaters (24 tm)+Y VCHP-XLHP Intf (12 tm)+Y VCHP-DSHP Intf (12 tm)

JL-69 JL-39 JL-35

16 pr tm

28 pr tm

JL-38

JL-32JL-30

JL-36

36 pr tm

-Y Grid Rad Intf (4 tm)2 -Y Grid Make Up Heater (4 tm)-Y Radiator (8 tm)

32 pr tm

14 prtm

14 prtm

JL-228

JL-1

21

JL-1

18

JL-234

JL-156 … 179

??

JL-180 … 203

x 24

GLAST LAT WIRINGDIAGRAM

REV 06

FEB 27, 2003 PY

JL-153

JL-2

04

… 2

27

8 pr tm + 40 pr vm

4 pr tm +20 pr vm

SPAREANALOGS

4 pr tm +20 pr vm

2 pr vm

2 pr vm 2 pr vm

2 pr vm

vm

vm

vm

vm

1 pr im

1 pr im

1 pr im

1 pr im

JL-1

15

2 pr tm

2 pr vm

JL-229JL-233

JL-235 JL-231

6 -Y VCHP Heater (12 tm)

6 +Y VCHP Heater (12 tm)+Y VCHP-XLHP Intf (4 tm)

JL-?

JL-151JL-148JL-145

JL-138JL-135JL-132

NOT USED CONNECTORNUMBERS

KEY:pr pairc controlgnd groundpwr powervm voltage monitorim current monitortm temp monitor

emi shieldspacecraftlocated +X sidelocated -X sidelocated +Y sidelocated -Y side

HDS high density D socketHDP high density D plugUDS micro D socketUDP micro D plugCIRC1S circular series I socketCIRC1P circular series I plugCIRC2S circular series II socketCIRC2P circular series II plug

JL-152

Reference TypeJL-1 55-CIRC1PJL-2 55-CIRC1PJL-3 55-CIRC1PJL-4 55-CIRC1PJL-5 26-HDPJL-6 26-HDPJL-7 78-HDSJL-8 78-HDSJL-9...12 26-HDSJL-13…28 26-HDSJL-29 37-UDSJL-30 100-UDSJL-31 100-UDSJL-32 100-UDSJL-33 100-UDSJL-34 100-UDSJL-35 37-CIRC2?JL-36 79-CIRC1SJL-37 100-CIRC1SJL-38 100-CIRC1SJL-39 26-HDSJL-40 78-HDPJL-41 78-HDPJL-42 62-HDSJL-43 62-HDSJL-44 100-UDSJL-45 100-UDSJL-46…49 100-UDSJL-50…65 51-UDPJL-66…68 100-UDPJL-69 100-UDSJL-70…72 26-HDPJL-73…88 51-UDPJL-89…104 26-HDPJL-105JL-106JL-107 26-HDSJL-108 26-HDSJL-109 100-UDSJL-110 100-UDSJL-111…114 26-HDPJL-115 13-CIRC1PJL-116 13-CIRC1PJL-117 66-CIRC1PJL-118 66-CIRC1PJL-119 13-CIRC1PJL-120 13-CIRC1PJL-121 66-CIRC1PJL-122 66-CIRC1PJL-123 22-CIRC1PJL-124 66-CIRC1SJL-125 66-CIRC1SJL-126JL-127JL-128JL-129JL-130JL-131JL-132 NOT USEDJL-133JL-134JL-135 NOT USEDJL-136JL-137JL-138 NOT USEDJL-139JL-140JL-141JL-142JL-143JL-144JL-145 NOT USEDJL-146JL-147JL-148 NOT USEDJL-149JL-150JL-151 NOT USEDJL-152 66-CIRC2?JL-153 51-UDPJL-154 26-HDPJL-155 100-UDPJL-156…179 100-UDPJL-180…203 79-CIRC2?JL-204…227 79-CIRC2?JL-228…235 MIL1553



SHIELDINGSHIELDING



Monitoring & Thermal Control OutlineMonitoring & Thermal Control Outline

• Overview• Temperature Monitoring (Matrix)• Voltage/Current Monitoring (Matrix)• Operating Temperature Control• Survival• Summary



MonitoringMonitoring

ACD

ACD

0 11

EPUP0

EPUR

SIUR

SIUP

TEM 0

CAL

TKR

TEM15

CAL

TKR

MonitoringP

PDU

Via CommunicationProtocolVia Sensor Wires

V/T toSC P/R

GASU

V/T toSC P/R

V/T toSC P/R

MonitoringR

V/T toSC P/R

Sensors Pexternal ofLAT EMIshield

Sensors Pexternal ofLAT EMIshield

T toSC P

T toSC R

V/T toSC P/R

• 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



Temperature Monitoring (SC & PDU)Temperature Monitoring (SC & PDU)Name Type Spacecraft PDU

Prime Redundant PrimeRedundan

t

ACD Tiles Thermal 5 5

ACD TSA Shell (inside) Thermal 5 5

ACD TSA Shell (outside) Thermal 2 2

ACD BEA-Grid interface Thermal 2 2

ACD PMT Rail Thermal 4 4 4 4

Calorimeter Baseplate Thermal 16 16

SIU Thermal 2 2

PDU Thermal 2 2

EPU Thermal 3 3

GASU Thermal 2 2

TEM DAQ Board Thermal 16 16

TEM pwr Supply Thermal 16 16

Radiator Anti-Freeze Htr Thermal 4 4

Radiators Thermal 8 8 10 10

Grid-Radiator interface Thermal 4 4 4 4

Grid Make-up Heaters Thermal 4 4

VCHP-XLHP interface Thermal 4 4 12 12

X-LAT Plate Thermal 4 4

VCHP-DSHP interface Thermal 12 12

Grid Thermal 12 12

VCHP's Reservoir Htr Thermal 12 12 24 24

VCHP Reservoir Htr Pri/Sec Voltage 4 4

Spare Temp. Channels Thermal 8 8



Temperature Monitoring (TEM & GASU)Temperature Monitoring (TEM & GASU)

Name Type TEM GASU

Prime Redundant

ACD FREE Thermal 12 12

CAL AFEE Thermal 128

AEM Power Supply Thermal 1 1

AEM DAQ Board Thermal 1 1

TKR Cables Thermal 256

• LAT Instrumentation Plan: LAT-SS-00890• Spacecraft ICD: GSFC-IRD-433



Voltage/Current MonitoringVoltage/Current Monitoring

Name Type Spacecraft PDU TEM GASU

Prime Redundant Prime Redundant

VCHP Reservoir Htr Pri/Sec Voltage 4 4

SIU Pri/Sec 3.3/5V V Voltage 2 2

PDU Pri/Sec 3.3V V Voltage 2 2

GASU Pri/Sec 3.3/28V/3.3VA V Voltage 2 2 6 6

EPU 3.3V V Voltage 4 4

TEM 3.3V V Voltage 16 16

ACD FREE V Voltage 12 12

ACD FREE I Current 1 1

ACD HV (I) Current 24 24

TKR V Voltage 64

TKR I Current 64

CAL V Voltage 48

CAL I Current 48

TEM DAQ V Voltage 16

TEM DAQ I Current 16

LAT SIU Bus V Pri/Sec Voltage 2 2

LAT VCHP Bus V Pri/Sec Voltage 2 2

Spare Voltage Channels Voltage 18 18

Total 32 32 20 20 256 43 43



Heater ControlHeater Control

ThermostatGRID/VCHPAnti-

FreezeHeaters

SpacecraftPower

MOS FET

VCHPHeaters

SpacecraftPower

SIU

• 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



Instrument ProtectionInstrument 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



High and Low TemperaturesHigh 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

SC: TDRSSWarning to

Ground

Yellow HighLimit

SC: TurnsLAT SIU/

DAQ Poweroff

Red HighLimit

LAT off or LATprocessor stuck

Within T limits

LAT SIU controls VCHPheater switches

VCHP Heaterspowered, Radiators

isolated

LAT on, LAT processoroperating, Thermal

Control enabled

Within T limits

LAT-LATTemp sensors

SC: Processing of Temperatures, monitoring of Heater Feeds

LAT-SC Tempsensors

Radiators not isolated(Malfunction of SIU/

heaters/SC feed)

Red Low Limit

SC: TDRSSWarning to

Ground

Yellow Lowlimit

T out of limits

SC: TurnsLAT SIU/

DAQ Poweroff



ACD PMT ProtectionACD 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

ACD high-voltagesupplies limit current

LAT power on,processor mal-function

ACD PMT high-voltagelowered

LAT on, LAT processoroperating, LAT

commanding enabled

Within currentlimit

SC SAAindicationcommands

At current limit

LAT power off

SAA

No high-voltage

SAA



SummarySummary

• 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



Tracker ElectronicsTracker 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



Calorimeter ElectronicsCalorimeter 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



ACD ElectronicsACD 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

GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 1 Changes since PDR...

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Transcript of GLAST LAT ProjectCDR/CD3 May 12-15, 2003 G. Haller 4.1.7 Elec LAT Design 1 Changes since PDR...