Transcript Purpose Protect the stave

Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Serial Powering - Protection
Purpose
Protect the stave
Assure supply of power to a serial powered chain of modules
when one member of the chain fails
Control the stave
Allow power to arbitrary selection of modules
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Why add protection?
Power failure modes
Open circuit module
Wire bonding failure
Noisy module
Without protection, one failed module can adversely affect the operation of all other modules on stave
Demonstration staves are very reliable - Protection is not strictly necessary
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
How to add protection?
Short out affected module(s)
One module out-of-service
The switch should respond to module
over-voltage and to DCS control
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-- Switch on -Short out and disable this module
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Issues to address
But…
How does the protection do its job?
Circuit options default state connections
Is automatic protection required?
Feedback from hybrid current/voltage
How fast must the protection react?
Reaction time
Is DCS control/reporting required? (yes)
Implementation requirements AC coupling
Automatic and/or DCS
How is the protection controlled?
Switching must not affect the rest of the SP chain? Transient effects on problem &/or power-up
Bus-cable or hybrid
Where should the switch be placed? (hybrid)
Numerical failure analysis
Quantitative estimate of failure rate?
Switch failure modes, fail safe, mass,
What extra complexity can we justify?
possibility of common mode failure,
monitoring
Is protection needed for other powering configurations?
Note that independent module voltage monitoring
may be available through the shunt regulator
device if using an “intelligent” component such as
SPi, but this may not be possible if there is a an
open-circuit module. However, it may be possible
to identify a faulty module by switching all
modules off, then each one on in turn.
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Qualitative target specification
DCS should be able to switch off (short-out) selected modules
Residual voltage (when ‘off’) < 100mV
Minimise number of components, area of components and bus-cable lines
Position on hybrid is acceptable
Over-voltage & over-current automatic protection is desirable
Switching a working module on/off must not affect the behaviour of other modules
During normal operation (module working) protection draws no power
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Examples
Can we use just one transistor for the task of shorting and SR?
OR
Less material, but possibility of common mode failure
Can we accept the risk of wire-bonds carrying power from bus-cable to hybrid
or should protection be placed directly on the bus-cable?
OR
Easier to implement, but depends on good wire bonding
Can SR and protection be included in a single ASIC package?
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
a) Circuit option
No active
protection
This option has been
sufficient for
demonstration
staves. This is a
serious option for the
ATLAS upgrade.
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+ simple
minimum mass, minimum
lines
engineered redundancy
including thick wire bonds
& several shunt transistors
- Cannot switch
modules off
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
b) Circuit option
Bonn
Each module has
a single line to an
off-detector
controller. This
can be used to
switch the
module off (short
it) or to monitor
the module
voltage.
Ref ATLAS Tracker Upgrade Workshop, NIKHEF 3-7 Nov 2008
Powering, Wed 5 Nov 2008, 17:30 Laura Gonella
http://indico.cern.ch/conferenceTimeTable.py?confId=32084
OC = Open Circuit (ie switch is “off”, module powered)
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+ simple
+ control & monitor
default state = OC
- no fast autoresponse
- many bus-cable wires
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
c) Circuit option
BNL
A common
data line fed
to a one-wire
controller
output is
latched and
used on each
module to
switch the
module off
(short it).
Ref
ATLAS Tracker Upgrade Workshop, NIKHEF 3-7 Nov 2008
Electronics Working Group, Tue 4 Nov 2008, 15:40 David Lynn
http://indico.cern.ch/conferenceTimeTable.py?confId=32084
OC = Open Circuit (ie switch is “off”, module powered)
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+ latching control
+ single DCS wire
+ fast auto-response
default state = OC
- no monitor
- low residual moduleoff voltage required
to hold latch
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
d) Circuit options
Villani
Similar to
the Bonn
design, but
power is
delivered
to the onewire
controller
and latch
by the data
line.
OC = Open Circuit (ie switch is “off”, module powered)
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+ latching control
+ “single” DCS wire
+ no trickle power
default state = OC
- no monitor
- no auto-response
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
e) Circuit options
Extended
As Villani
design, but
latch may
also be set in
the safe state
using the
shunt
regulator
alarm. Also
consider
depletion
mode FET for
fail-safe.
SC = Short Circuit (ie switch is “on”, module un-powered)
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+
+
+
+
latching control
single DCS wire
no trickle power
auto-response
default = SC
- no monitor
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Comparison
Demonstrated
Extra area mm2
Extra module mass
Extra active module components
Extra passive module components
Extra bus-cable lines
Circuit complexity
Minimum (‘off’) voltage
Latching
Auto over-current protection
Auto over-voltage protection
Proposal
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No protection
N
N
N
n/a
L
0
0
0
0
0
Y
Bonn
N
N
N
0
L
n
2
1
?
?
?
BNL
Y
N
Y
?
M
2
4
3
?
100
Y
Villani
N
N
Y
0
H
2
?
?
?
?
½
Extended
Y
Y
Y
0
H
2
?
?
?
?
N
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Summary
…circuit options are being
implemented and evaluated…
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
End
…circuit designs follow…
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Bonn protection
Copied from presentation by Laura Gonella
ATLAS Tracker Upgrade Workshop, NIKHEF 3-7 Nov 2008
Powering, Wed 5 Nov 2008, 17:30
http://indico.cern.ch/conferenceTimeTable.py?confId=32084
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Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
BNL protection
IN
ZXTDA1M832
PNP-NPN
Single Package
EDZTE613.6
Module
V
P
5k
SI 1450DH
1k
I/O
8 nF
Gnd
Ds2413
Protection
Copied from presentation by David Lynn
ATLAS Tracker Upgrade Workshop, NIKHEF 3-7 Nov 2008
Electronics Working Group, Tue 4 Nov 2008
http://indico.cern.ch/conferenceTimeTable.py?confId=32084
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OUT
Richard Holt – Rutherford Appleton Laboratory
ATLAS SCT SP protection options
January 2009
Villani protection
From Giulio Villani, RAL – personal communication
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