Transcript Fabio_MPE-TM_11_10_10

Technical review Vearth board
• Held on June 30th
• Designer: Joaquim
• Reviewers: Reiner, Betty, Gonzalo, Fabio
• Architecture
Single A to D channel based on ADuC834 24bits sigma delta converter with integrated µC
Analog functions with full galvanic insulation
• Application
Adding the capability of measuring potential to ground of the magnet 13kA power lines
Only monitoring functions, no interlock, no protection
• Quantities
Total:
1270 (plus spares)
Pre-series:
160 (plus spares), for typically 10 per magnet type and per sector
• Installation: winter shut down 2010/2011
F. Formenti - MPE Tech Meeting - October 11th, 2010
Discussion topics
1.
Boards are located in areas not very critical for radiation and their application is not critical
 for coherence with other QPS units, radiation tolerance tests will anyway be performed in CNGS
to validate operative safe margins.
2.
Readout sampling is ~5Hz limited by supervision layer
 judged appropriate for the function
3.
24 bits (0.3µV/LSB @ 5V) resolution and 1/833 voltage divider => ~250mV/LSB @ probe point
 much finer than required, voltage divider for dipoles OK also for quadrupoles
4.
Technical documentation to be prepared and stored on public space by Joaquim
F. Formenti - MPE Tech Meeting - October 11th, 2010
More discussion topics
To prevent contact sticking,
find normally close relay
Mistake correction for
galvanic insulation
Mistake correction
Remote power
cycle if I2C hangs
For best HV protection
in board layout
Either external or internal
protection diode for relay
The board layout shall be optimized avoiding “crossing”:
- between analogue and digital lines
For best EMC
To prevent permanent
divider short to GND
- between HV lines and ground references.
Power lines and correspondent return to grounds shall
be routed as close parallel lines or full planes
F. Formenti - MPE Tech Meeting - October 11th, 2010
Conclusions
No showstoppers to proceed with the prototype construction
but the layout shall be re-studied and optimized for HV, power distribution and EMC
Correction of a few circuit mistakes to be implemented as noted
I2C remote power cycle is recommended
Radiation tolerance tests on prototype shall be performed at CNGS to check operation safe margins
Documentation to be produced and stored in public database.
F. Formenti - MPE Tech Meeting - October 11th, 2010