1. Lar PHase2
F. Tartarelli, M. Citterio, M. Lazzaroni

2. Introduction
L’upgrade di Fase II di LAr, prevede che l’elettronica di Front-End e di Back-End sia completamente cambiata
Milano si è proposta per progettare:
lo schema di alimentazione per la nuova elettronica di Front-End
la distribuzione e regolazione delle alimentazioni sulle schede di Front-End
Il documento IDR è stato mandato ai revisori di ATLAS il Dic
La data per la review dell’IDR non è ancora nota
Il TDR deve essere preparato entro l’Autunno 2017
M. Citterio
CSN1 - 6 Febbraio 2017

3. LAr LVPS
New electronics -> new LVPS providing lower supply voltages
Two options under study
OPTION 1: New powering scheme  Distributed Power Architecture (DPA)
Optimized Voltage Drop
High static regulation and improvement of the dynamic performances
(the impact of the series resistance and inductance is reduced)
The DPA approach benefits from increased efficiency, low size and weight, especially if the “main converter” is really near the front-end electronics
M. Citterio
CSN1 - 6 Febbraio 2017

4. Option 1
Rationalization of the number and levels of the voltages required by the Front End electronics
one or two intermediate voltages must be supplied
loads must be served by PoLs regulators
Based on the availability of PoLs
rad tolerant
Proper sizing of max current (several Amps) to match the load requirements
magnetic tolerant
New design of the “main converter”
tolerant to higher radiation levels
modular approach
high reliability / low maintenance
optimized design of magnetic devices
low losses and heat
M. Citterio
CSN1 - 6 Febbraio 2017

5. Option 2: Move LVPS away from detector
Re-evaluate possibility to move LVPS away from the detector,
requested (RECENTLY) by LAr Collaboration
Pros:
LVPS in a more accessible location
Use of commercial crates/boards could be possible
LVPS no more constrained in size/space between two Tile fingers
Less radiation
Cons:
Where? Eg, near Pixel PP2? Need to find room for new crates and cables
How far from load? What length/section of cables needed?
Higher magnetic field (dependent from location)
Might require using a higher IBV (48V)
then not easy to go from 48V to low voltages in one step on the FEB (introduce intermediate step!?)
M. Citterio
CSN1 - 6 Febbraio 2017

6. RD_FASE2
In the last two years with RD_FASE2 we have explored only the on-detector solution (Option 1) by designing:
1. A custom LVPS
First prototype realized with CAEN help
Fully functional, but it needs improvement in efficiency
and selection of rad-tolerant components
- GaN devices tested as possible substitute to Si Power MOSFETs
2. An LVPS based on commercial converters
tested two commercial devices (Vicor BCM® Bus Converter) which passed neutron tests but failed TID tests
On-going searching of other type of “power bricks”
Finanziamenti:
Ricevuti 20 (2015) + 20 (2016) keuro
Richiesti ulteriori 20 keuro nel 2017
Utilizzati per componenti, moduli LV, board di test, adattamento del prototipo costruito con CAEN
M. Citterio
CSN1 - 6 Febbraio 2017

7. Next steps towards TDR
Investigate the space necessary for moving converter/cable out of finger region (OPTION 2)
with CERN help we are reviewing drawings and collecting information
Specification definition
- power budget in relation to location
- voltage drop along cables
- modularity, i.e. crates dimension ….
- power dissipation at the converter
If feasibility is understood soon then  Before TDR in any case !
search for possible commercial solutions (CAEN? others?)
- including “small modifications” to existing system
If no commercial system exists, we will try to re-use solutions studied for RD_FASE2
M. Citterio
CSN1 - 6 Febbraio 2017

8. Next steps
Independently from the option selected we need to initiate a collaboration with a commercial partners
If OPTION 1 is chosen
to “move” from a INFN prototype design to a robust/final product
to construct converters in quantity
to provide support on the long term
If OPTION 2 is chosen
to “customize” a commercial system, if it exists
to build a new pre-production module
following LAr specification
according with the results from RD_Fase2
M. Citterio
CSN1 - 6 Febbraio 2017

9. Milano Involvement Up to TDR Continuation of RD_FASE2 activities
Choice between OPTION 1 and 2
Long Term Engagement
Test and validation of “first article” converter/system
Selection of POL to be mounted on Front-end board
Burn-in of one/two “first modules” done at INFN Milan
More extensive burn-in will be done by CERN, using existing facilities
M. Citterio
CSN1 - 6 Febbraio 2017

10. Core costs and schedule
From the IDR Document
From IDR document
Total costs for INFN: kCHF
in respect to a gran total of 3123 KCHF (45 %)
Manpower:
Run 2 + Fase 1: 3.4 FTE
Fase 2: 3.8 FTE
M. Citterio
CSN1 - 6 Febbraio 2017

11. Back up
M. Citterio
CSN1 - 6 Febbraio 2017

12. Schema di alimentazione corrente (Phase 0 and Phase I)
Centralized power distribution architecture
Many isolated converters/distributors generate a set of 7 regulated DC voltages to be provided to the subsystem circuits
M. Citterio
CSN1 - 6 Febbraio 2017

13. Schema di alimentazione corrente
Main characteristics:
Converter located “as close as possible” to the load, to avoid high number of long cables
Converter accessible only during “long shut-down”
Constrained between two Tile fingers
Dimensions: ~ 15x30x40 cm^3
Converters supply several KW per unit
Power Supply exposed to radiation and a “moderate” magnetic field (< 1 kG)
Extensive use of LDO regulators
M. Citterio
CSN1 - 6 Febbraio 2017