GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
CDR/CD-3 Review May 12-16, 2003
GLAST Large Area Telescope:
Electronics, Data Acquisition &
Flight Software
LAT Electronics Design
Engineering
Gunther Haller
Stanford Linear Accelerator Center
Manager, Electronics, DAQ & FSW
LAT Chief Electronics Engineer
haller@slac.stanford.edu
(650) 926-4257
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
1
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Electronics Physical
TKR Front-End Electronics (MCM)
ACD
ACD Front-End Electronics (FREE)
TKR
CAL Front-End Electronics (AFEE)
CAL
Global-Trigger/ACD-EM/Signal-Distribution
(GAS) Unit*
Spacecraft Interface
Unit
– Storage Interface
Board (SIB):
EEPROM
SC MIL1553
control & data
– LAT control CPU
– LAT
Communication
Board (LCB): LAT
command and
data interface
16 Tower Electronics Modules
– DAQ electronics module (DAQ-EM)
– Power-supplies for tower electronics
3 Event-Processor Units (2+1 spare)
– Event processing CPU
– LAT Communication Board (LCB)
– Storage Interface Board (SIB)
EPU-1
EPU-2
Pw r Dist. Box
spare
spare
GASU
spare
spare
spare
SIU-P
SIU-R
EPU-3
Power-Distribution Unit (PDU)*
– Spacecraft interface,
power
– LAT power distribution
– LAT health monitoring
* Primary & Secondary Units shown in one chassis
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
2
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Electronics
•
•
•
•
•
•
•
•
TKR: Tracker
CAL: Calorimeter
ACD: Anti-Coincidence Detector
EPU: Event Processor Unit
SIU: Spacecraft Interface Unit
GAS Unit: Global Trigger-ACD-Signal
Distribution Unit
TEM: Tower Electronics Module
There are
– 2 prim EPU’s, 1 redundant EPU
(not shown)
– 1 prim SIU, 1 redundant SIU (not
shown)
– 1 prim GAS, 1 redund. GAS (not
shown)
– 1 prim PDU (not shown), 1
redundant PDU (not shown)
Document: LAT-PR-01967
SC
SC Science
Commanding
Data
EPU 0
EPU 1
SIU
GAS Unit
Event
Builder
TEM 0
C
A
L
T
K
R
Command
Response
Unit
Global
Trigger
TEM 1
C
A
L
T
K
R
TEM 15
C
A
L
T
K
R
ACD Electronics
Module
A
C
D
A
C
D
A
C
D
0
1
11
Section 8.2 LAT Elec Design v5
3
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Tracker Electronics
GTRC ASIC
•
•
GTFE ASIC
TKR sub-system electronics
• Si-Strip Detectors
• 24 GTFE (GLAST Tracker Front-End) ASICs (1,536 signal channels)
• 2 GTRC (GLAST Tracker Readout Controller) ASICs
• MCM (Multi-Chip Module)
• Flex-cables
Presented in tracker sub-system presentation
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
4
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Calorimeter Electronics
GCRC ASIC
GCFE ASIC
•
•
CAL sub-system electronics
• Diodes
• 48 GCFE (GLAST Calorimeter Front-End) ASICs
• 4 GCRC (GLAST Calorimeter Readout Controller) ASICs
• AFEE (Analog Front-End Electronics) board
Presented in calorimeter sub-system presentation
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
5
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
ACD Electronics
•
•
GAFE ASIC
ACD sub-system electronics
• PMT’s
• 18 GAFE (GLAST ACD Front-End) ASICs
• 1 GARC (GLAST ACD Readout Controller) ASIC
• FREE (Front-End Electronics) board
• High-Voltage Supply board (not shown)
Presented in ACD sub-system presentation
Document: LAT-PR-01967
GARC ASIC
Section 8.2 LAT Elec Design v5
6
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
DAQ Electronics
•
•
DAQ sub-system electronics
• SIU, EPU, GASU, PDU, TEM, Harness, Instrument Software
– Example shown is Tower Electronics Module Engineering Unit
Presented in DAQ & Instrument Software presentations
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
7
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
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 SCLAT interface level and lead to
removal of direct SIU-SIU interconnections
Document: LAT-PR-01967
Before SC selection
spare
EPU-1
EPU-2
EPU-3
spare
spare
GASU
spare
spare
SIU P/R
Pwr Dist. Box P/R
After SC selection
EPU-1
EPU-2
Pwr Dist. Box
spare
spare
GASU
spare
spare
spare
SIU-P
SIU-R
EPU-3
Section 8.2 LAT Elec Design v5
8
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
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
(renamed SIB to Storage Interface Board)
– 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.
Document: LAT-PR-01967
SC
SC Science
Commanding
Data
EPU 0
EPU 1
SIU
GAS Unit
Event
Builder
TEM 0
C
A
L
T
K
R
Command
Response
Unit
Global
Trigger
TEM 1
C
A
L
T
K
R
TEM 15
C
A
L
T
K
R
ACD Electronics
Module
A
C
D
A
C
D
A
C
D
0
1
11
Section 8.2 LAT Elec Design v5
9
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Spacecraft Interface
•
•
•
•
•
•
•
•
Power (to SIU, PDU, Heaters)
– 28V regulated and unregulated
MIL1553 (to/from SIU)
– Commanding, house-keeping
Science Interface (from GASU)
– Transport of science data to spacecraft solidstate recorder
1-PPS timing signal (to GASU)
– Timing pulse
GBM GRB Candidate signal (to GASU)
– Notification of candidate Gamma-Ray Burst
(GRB), from GBM routed through SC
Discretes (to/from SIU))
– Pulsed and level digital signals from and to
spacecraft
Analog Monitoring (from entire LAT)
– Temperature and voltage monitoring by SC;
available even when LAT is off
Two sets of power & signals: Prime and redundant
Spectrum Astro SC-LAT Interface Document
Document: LAT-PR-01967
Power
MIL1553
SPACECRAFT
Science Data
LAT
1 PPS
GBM GRB
Candidate
Discretes
Digital
Analogs
Section 8.2 LAT Elec Design v5
10
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
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
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
To other thermostats/
heater zones
Unregulated
Voltage
Primary
to
to
to
to
GRID or AntiFreeze
Heaters,
several
zones, each
zone has its
own set of
thermostats/
heaters
Prime
To other thermostats/
heater zones
Unregulated
Voltage
Primary
to
to
to
to
Redundant
To other switches
(12 total)
Regulated
VCHP Voltage
Primary
Prime
To other switches
(12 total)
Turn on control from
SIU P and SIU R
VCHP
survival/
operational
heaters
Regulated
VCHP Voltage
Redundant
All switches are
controlled by
spacecraft
Redundant
Turn on control from
SIU P and SIU Rl
Regulated
SIU-Prime
Voltage
SIU
Prime
Regulated SIURedundant
Voltage
Regulated Main
DAQ Prime
Voltage
Regulated Main
DAQ Redundant
Voltage
Document: LAT-PR-01967
LAT
SIU
Redun
dant
Crossconnected:
either PDU
can use
either feed
Section 8.2 LAT Elec Design v5
PDU
Prime
Power to rest
of LAT
PDU
Redun
dant
11
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Spacecraft 1-PPS and GRB Candidate Signal (to
GASU)
Spacecraft
1-PPS P
LAT
Multiplexer
S1 E D
S2 N
CB
Fan-Out
GASU DAQ Board Prime
1-PPS R
Multiplexer
S1 E D
S2 N
CB
Multiplexer
S1 E D
S2 N
CB
E.g SIU P
To other crates
GASU DAQ Board
Redundant
•
•
•
•
•
•
1-PPS signal from spacecraft (prime and redundant) are connected to both GASU boards
(prime and redundant)
GASU selects which SC signal to use
Result is fanned out to all processor crates (SIU’s as well as EPU’s)
– prime and redundant signals are connected to discrete RAD750 processor inputs (PID’s)
• Software select which 1-PPS to use
SC-LAT components are fully cross-connected
Same for GBM GRB candidate signal
LAT needs to know which SC-port or GBM-port to listen to
– Ground commanding
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
12
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Spacecraft Discrete Signals & MIL1553 (to SIU)
Spacecraft
LAT
CPU
Discretes P
SIU Crate Prime
Discretes R
SIU Crate Redundant
•
•
•
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
MIL1553 Command/Data (not shown)
– Command & Data interface to both, SIU P and SIU R
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
13
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT-SC Science Interface (from GASU)
Spacecraft
LAT
To other LAT CPU’s
Switch
Receiver P
Multiplexer
D E S1
N S2
BC
SIU P
GASU Event-Builder Prime
Receiver R
Multiplexer
D E S1
N S2
BC
To other LAT CPU’s
2 SIU’s,
3 EPU’s
EPU R
GASU Event Builder Redundant
•
•
•
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 Event-Builder (P or R) to SC
Data is driven to both SC sections (P and R)
– SC needs to select which GASU to listen to
– LAT GASU needs to know which SC port (P or R) flow-control line is active
– All configured via ground commanding
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
14
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Connections LAT/Spacecraft and to LAT EMI
Shield
16 pr pwr
(2 pr tm + 2 pr vm, pdu Prim & rdnt) + (2 pr tm + 2 pr vm, gasu Prim & rdnt)
SC PRU
Prim
25A
regulated
28 pr tm
ACD Temp
Sensor Bracket
JL-131
+Y Grid Rad Intf (4 tm)
2 +Y Grid Make Up Heater (4 tm)
+Y Radiator (8 tm)
32 pr tm
2 pr pwr (AWG18)
JL-133
2 pr pwr (AWG18)
JL-136
4 pr pwr
+Y Heater
Control Box
HTR
JL-134
4 pr pwr
2 +Y Grid Make Up Heater Prim
JL-137
4 pr pwr
2 +Y Grid Make Up Heater Rdnt
2 pr pwr + 2 pr vm (+Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)
JL-127
JL-128
4 pr pwr
12 pr pwr
2 +Y Rad Antifreeze Heater Prim
6 +Y VCHP Heater Prim
2 pr pwr + 2 pr vm (+Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)
JL-129
JL-130
4 pr pwr
12 pr pwr
2 +Y Rad Antifreeze Heater Rdnt
6 +Y VCHP Heater Rdnt
16 pr tm
16 pr tm
ACD
Electronics
Box
(x 24)
ACD
[ FROM ACD TO PDU ]
ACD BEA-Grid Intf (4 tm)
ACD PMT Rail (8 tm)
ACD Shell (4 tm)
EPU
Box
(test only)
JL-154
4 pr tm + 4 pr vm
JL-204 … 227
+Y Radiator
Bracket
32 pr tm
SC PDU
Prim
unregulated
[ FROM ACD TO SC ]
ACD Tiles (10 tm)
ACD PMT Rail (8 tm)
ACD Shell (10 tm)
JL-152
+Y VCHP-XLHP Intf (4 tm)
6 +Y VCHP Heater (12 tm)
1 pr im
JL-155
1 pr im
EGSE
16 pr tm
JL-126
4 pr tm
48 pr tm
4 pr tm
JL-180 … 203
JL-105
JL-69
JL-39
JL-35
+Y VCHP Heaters (24 tm)
+Y VCHP-XLHP Intf (12 tm)
+Y VCHP-DSHP Intf (12 tm)
JL-37
11 pr science
8 pr tm
XLAT plate
??
EPU
EPU
Box
(x 3)
4 pr pwr +
2 pr tm +
2 pr vm
JL-113
100
JL-231
JL-5
JL-153
4 pr tm +
4 pr vm
x3
GASU
16 pr LATP +
8 pr pwr +
2 pr tm + 2 pr vm
16 pr LATP +
8 pr pwr +
2 pr tm + 2 pr vm
16 pr pwr
PDU
(8 c)*2 + 8 gnd
4 pr pwr
JL-112
2 pr vm
JL-116
JL-120
2 pr vm
12 c + 6 gnd
51
11 pr science
2 pr 1PPS +
2 pr GRBM
JL-125
JL-34
TEM
Box
(x 16)
TEM
JL-89-104
12 c + 6 gnd
4 pr pwr + 4 pr tm + 2 pr vm
Grid (12 tm)
Cal baseplate (16 tm)
JL-?
JL-106
JL-36
JL-38
SPARE
ANALOGS
48 pr tm
-Y VCHP Heaters (24 tm)
-Y VCHP-XLHP Intf (12 tm)
-Y VCHP-DSHP Intf (12 tm)
36 pr tm
Grid Rad Intf (8 tm)
Radiator (20 tm)
Radiator Antifreeze Heaters (8 tm)
JL-139
2 pr 1PPS +
2 pr GRBM
16 pr tm
2 pr pwr + 2 pr vm (-Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)
JL-140
JL-141
12 pr pwr
4 pr pwr
6 -Y VCHP Heater Prim
2 -Y Rad Antifreeze Heater Prim
2 pr pwr + 2 pr vm (-Y VCHP, sum of 6 Prim sw & sum of 6 Rdnt sw)
JL-142
JL-143
12 pr pwr
4 pr pwr
6 -Y VCHP Heater Rdnt
2 -Y Rad Antifreeze Heater Rdnt
2 pr pwr (AWG18)
JL-146
JL-147
4 pr pwr
2 -Y Grid Make Up Heater Prim
2 pr pwr (AWG18)
JL-149
JL-150
4 pr pwr
2 -Y Grid Make Up Heater Rdnt
16 pr tm
4 pr pwr
HTR
-Y Heater
Control Box
LAT EMI shield
-Y Radiator
Bracket
4 pr tm + 4 pr vm
8 pr tm + 40 pr vm
1 pr im
1 pr im
JL-32
JL-124
11 pr science
SC PDU
Rdnt
unregulated
JL-30
28 pr tm
JL-73-88
JL-114
4 pr pwr +
4 pr vm
4 pr vm
GRBM Prim/
Rdnt
JL-13 … 28
22 pr science +
2 pr 1PPS +
2 pr GRBM
vm
4 pr tm +
20 pr vm
Timing Prim/
Rdnt
JL-4
x 16
22 pr science +
2 pr 1PPS +
2 pr GRBM
vm
SC PRU
Rdnt
2.8 A
regulated
JL-6
SIU R
SIU
Rdnt
2 pr vm
4 pr tm +
4 pr vm
JL-50 … 65
JL-43
JL-108
JL-42
JL-118
JL-122
SC Analog
Monitor Rdnt
2 pr tm
16 pr pwr
x 16
12 pr discrete
12 pr discrete
PDU
Box
JL-8
JL-45
JL-110
100
JL-1
JL-230
1 pr mil1553
JL-33
JL-3
1 pr mil1553
JL-235
JL-46,47,48
GASU
Box
SC
C&DH
Rdnt
JL-31
JL-7
JL-234
JL-49
x 24
100
JL-40
JL-229
JL-44
JL-228
1 pr mil1553
JL-109
1 pr mil1553
JL-233
JL-29
JL-2
JL-156 … 179
JL-232
JL-12
x3
(8 c)*2 + 8 gnd
12 pr discrete
SC
C&DH
Prim
JL-9,10,11
100
JL-41
12 pr discrete
JL-117
JL-121
2 pr vm
SIU P
SIU
Prim
2 pr tm
SC Analog
Monitor Prim
12 c + 6 gnd
JL-107
4 pr pwr
vm
4 pr tm +
20 pr vm
Grid (12 tm)
Cal baseplate (16 tm)
4 pr pwr + 2 pr tm + 2 pr vm
28 pr tm
2 pr vm
JL-115
2 pr vm
14 pr
tm
12 c + 6 gnd
vm
JL-119
14 pr
tm
4 pr pwr +
4 pr vm
JL-66,67,68
SC PRU
Prim
2.8A
regulated
JL-111
4 pr vm
JL-70,71,72
JL-123
11 pr science
32 pr tm
SC PRU
Rdnt
25A
regulated
JL-144
32 pr tm
6 -Y VCHP Heater (12 tm)
-Y VCHP-XLHP Intf (4 tm)
-Y Grid Rad Intf (4 tm)
2 -Y Grid Make Up Heater (4 tm)
-Y Radiator (8 tm)
(2 pr tm + 2 pr vm, pdu Prim & rdnt) + (2 pr tm + 2 pr vm, gasu Prim & rdnt)
Heater & Monitoring Box
16 pr pwr
Spacecraft
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
15
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Grounding and Shielding
SURVIVAL
LAT Grounding an Shielding Diagram
SPACECRAFT PDU
HEATERS
RADIATOR
SIU
1553
SSR
T
28 VOLT DISTRIBUTION
NOTE:
PDU, SIU, EPU,TEM_TPS,
TKR, CAL, BEA, and GASU
are housed in aluminum enclosures
LAT RF SHIELD
GRID IS BONDED TO
SPACECRAFT AT
FOUR LOCATIONS,
ONE ON EACH SIDE
OF THE LAT.
FILTER
TKR & CAL
FILTER
(1 of 16)
BEA BONDED
TO THE GRID
GASU
ACD BEA
FILTER
RESISTIVE
LOAD
TEM_TPS (1 of 16)
FILTER
TRANSFORMER
ISOLATION &
DC-DC CONVERTER
28 VOLT DISTRIBUTION
FILTER
EPU (1of2)
LAT GRID
(GROUND)
HSKP
PDU
FILTER
FILTER
HEATERS
FILTER
SPACECRAFT CD&H
FILTER
SPACECRAFT PRU
LAT
(1 of 8)
ACD CABLING
•
EMI/EMC: GSFC-355-RQMT
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
16
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Shielding
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
17
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Power Allocation
Quantity
Total
Mech On-Board Power
1
TEM--Tower Electronics Module
TEM board
16
Power Supplies
TKR,CAL,TEM
16
GASU--Global Tgr ACD, Signal Dist. Unit
EP, AEM, Sig Dist & Supplies
Current
Current
Case
Estimate
Allocation
286.20
313.79
318.00
359.85
38.00
35.00
38.00
38.00
43.20
46.70
48.00
54.32
2.70
2.92
3.00
3.39
148.50
163.29
165.00
186.72
9.28
10.21
19.80
22.37
1
Other Boxes
SIU--Spacecraft Interface Unit
Cold
1
EPU Total
Hot Case
11.67
22.00
24.90
22.37
74.70
81.43
83.00
93.92
21.60
23.89
24.00
27.16
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
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
18
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
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
Document: LAT-PR-01967
T to
SC P
T to
SC R
V/T to
SC P/R
V/T to
SC P/R
V/T to
SC P/R
V/T to V/T to
SC P/R SC P/R
SIU
P
Sensors P
external of
LAT EMI
shield
SIU
R
PDU
Monitoring
P
Sensors P
external of
LAT EMI
shield
GASU
Monitoring
R
Via Communication
Protocol
Via Sensor Wires
EPU
P0
EPU
R
TEM
15
TEM 0
C
A
L
T
K
R
C
A
L
T
K
R
A
C
D
A
C
D
0
11
Section 8.2 LAT Elec Design v5
19
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Temperature Monitoring (SC & PDU)
SC Action if
low or high
limit is
reached
Location of Sensor
Sensor Type
Sensors
by
processed
Spacecraft
Sensors
by
processed
PDU
Prime
Redundant
Prime
Redundant
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
Calorimeter Baseplate
Thermal
16
16
SIU
Thermal
2
2
PDU
Thermal
2
2
EPU
Thermal
3
3
GASU
Thermal
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
Document: LAT-PR-01967
4
2
4
2
Section 8.2 LAT Elec Design v5
20
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Temperature Monitoring (TEM & GASU)
Sensor processed by
Location
Sensor Type
TEM
GASU
Prime
Redundant
12
12
ACD FREE
Thermal
CAL AFEE
Thermal
AEM Power Supply
Thermal
1
1
AEM DAQ Board
Thermal
1
1
TKR Cables
Thermal
128
256
• LAT Instrumentation Plan: LAT-SS-00890
• Spacecraft ICD: GSFC-IRD-433
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
21
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Voltage/Current Monitoring
Location
Sensor Type
Sensed
by
PDU
Sensed by
Spacecraft
Prime
Redundant
Prime
Sensed
by
TEM
Sensed
by
GASU
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
EPU 3.3V V
Voltage
4
4
TEM 3.3V V
Voltage
16
16
ACD FREE V
6
6
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
32
32
43
43
Total
20
20
256
Note: LAT does not monitor currents or voltages on SC-LAT feeds
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
22
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
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 not exceeding
low or high survival temperatures lays
with SC
LAT-SS-00715 Thermal Control System ICD
Document: LAT-PR-01967
Spacecraft
Power
Thermostat
Spacecraft
Power
MOS FET
GRID/
VCHP
AntiFreeze
Heaters
VCHP
Heaters
SIU
Section 8.2 LAT Elec Design v5
23
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Instrument Protection: 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 T
– if T too high or too low
• SC puts LAT into safe
mode
• SC turns-off LAT SIU and
Main DAQ power
• SC may need to switch
heater feeds in cold case
– SC responsible for LAT
Document: LAT-TD-01553
Document: LAT-PR-01967
LAT-LAT
Temp sensors
LAT on, LAT processor
operating, Thermal
Control enabled
LAT off or LAT
processor stuck
LAT SIU controls VCHP
heater switches
VCHP Heaters
powered, Radiators
isolated
Within T limits
Radiators not isolated
(Malfunction of SIU/
heaters/SC feed)
Within T limits
T out of limits
LAT-SC Temp
sensors
Yellow High
Limit
SC:
Warning to
Ground
SC: Processing of Temperatures, monitoring of Heater Feeds
Red High
Limit
SC: Turns
LAT SIU/
DAQ Power
off
Yellow Low
limit
SC:
Warning to
Ground
Red Low Limit
SC: Turns
LAT SIU/
DAQ Power
off
Section 8.2 LAT Elec Design v5
24
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Instrument Protection: ACD PMT Protection
SC SAA
indication
commands
LAT on, LAT processor
operating, LAT
commanding enabled
SAA
LAT power on,
processor mal-function
LAT power off
SAA
No highvoltage
ACD PMT high-voltage
lowered
At current limit
Within current
limit
ACD high-voltage
supplies limit current
•
•
•
LAT turns down PMT high-voltage levels during SAA passage to
protect PMT’s
– In response to SC SAA notification, or
– When SC heard-beat is lost
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
Document: LAT-TD-01553
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
25
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Instrument Protection: Over-Current
• LAT does not monitor current on SC feeds
• SIU power feed not fused on LAT, SC has current limit switch
• Main DAQ feed power not fused on LAT, SC has current limit
switch
– LAT PDU distributes 28V to about 20 LAT loads. Each subfeed is fused on PDU via poly-switches
• Tower Electronics Modules convert and distribute power
(+1.5V, 2.5V, 3.3V, 0-100V, 0-150V) to TKR & CAL: Feeds are
fused on TEMs via poly-switches
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
26
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Summary
•
•
•
•
•
Interface to SC defined
Grounding and shielding of LAT defined
Monitoring of temperatures, voltages, and currents defined
Heater control defined
Instrument protection tree documented
– SC, not LAT has final responsibility to protect instrument
from damage in respect to temperatures
– SC has to meet power quality specifications to not damage
LAT
– LAT is responsible for SAA PMT survival
• First layer of protection software controlled
• Second layer (back-up) protection: hardware
– Over-current protection of electronics components via polyfuses
Document: LAT-PR-01967
Section 8.2 LAT Elec Design v5
27