Argonne National Laboratory is a U.S. Department of Energy laboratory managed by U Chicago Argonne, LLC.
• 2nd Measurement – Feb., 2011– Test board with individual components– 188 MeV protons– Discovered: LT1681 Controller Chip
trips & restarts
– Diode conducts at cold start– Diode is back biased– SEUs still happen, but recovery is fast
The TileCAL Low Voltage System
Radiation Testing Methodology
Measurements & Results
• Power for TileCAL Front-End Electronics• Novel Switching DC-DC Power Supply– Custom, Compact, High-Efficiency, 250 Watt– 8 Different Voltages Customized Bricks– Water Cooled; System Interface & Monitoring– Environment: Magnetic Field, Radiation Tolerant• 256 boxes on detector, 2048 bricks, + spares Reliability is Important Infrequent Access
End of Long Barrel Detector Section
LVPS Access
on Detector Drawer Electronics
LVPS Box8 bricks per Box
LVPS Brick
Single Event Upset Energy Dependence In a Buck-Converter Power Supply Design
Bruce Mellado2, Anusha Gopalakrishnan1, Sanish Mahadik1, Robert Reed2, Abhirami
Senthilkumaran1 1 - University of Wisconsin-Madison, Madison, WI USA
2 – The University of the Witwatersrand, Johannesburg, SAOn Behalf of the ATLAS Tile Calorimeter System
Gary Drake, Member IEEE, James Proudfoot
Argonne National Laboratory, Lemont, IL USA
• The Fix – Soft Start not used in brick operation– But, circuit does control startup rate Want capacitor for cold start Want capacitor out of circuit for normal operation Add a diode & resistor:
• Radiation Tolerance Requirements– 10 Years of Running, L = 1034 cm-2 sec-1
• 1st Measurement – Dec., 2010– Bricks tripped from SEU– 188 MeV protons
SEU Problem
We have performed a study of the susceptibility to Single Event Upsets (SEU) on the new upgraded supplies
TID (Grays)
NIEL Fluency (neutrons/cm2)
SEE Fluency
(protons/cm2)3.78 2.74x1011 6.74x1010
• SEU Testing Program– Proton beam at Mass. Gen. Hospital– 20 – 200 MeV protons– Read out continuously during irradiation
Soft-start capacitorExternal component
Value controls startup delay
Schematic
LT1681 Block Diagram
Soft Start Feature
• A Puzzle– SEUs not seen in earlier tests at 60 MeV– Why?...
• 3rd Measurement – Apr., 2011– Fix installed on 3 bricks– No more trips!
• 4th Measurement – Apr., 2012 Study SEUs as a function of energy
– 60 MeV, 80 MeV, 100.5 MeV, 140 MeV, & 216 MeV– Results: See energy dependence
Test Setup at MGH
Test Setup Configuration
Block Diagram of Brick
• Theory: Bendel Parameters [1] – In general, SEU susceptibility depends on fab tech., feature size, layout, and configuration
– Bendel Parameters: Parameterization of form:–Our fit:
[1] W.J.Stapor, et al., IEEE Trans Nucl. Sci., Vol. 37, NO.6, pp. 1966-1973, December 1990.
ToELMB(Control
Interface)
Startup
Shutdown
Opt
oIs
olat
orO
pto
Isol
ator
MonitorVoltages
VIN* IIN*
LT1681Controller
Chip
+
Vout
-
FETDriver
RSHUNT
VFB
IFB
Tran
sfor
mer
GNDSECGNDPRI
Startup&
ShutdownControl
OVP, OCP,
Temp, &
Monitor
RSHUNT
LC Filter
+
200V
-
LC Buck LC Filter
OpAmpRunStop
Over Temp
VOUT*
IOUT*
PR
IP
ower
SE
CP
ower
+VSEC
-
+VPRI
-
Isolated SecondaryPrimary
SEMI-EMPIRICAL 2 PARAMETER FIT