1. DC/DC Converter Update Markus Friedl (HEPHY Vienna) B2GM, 22 July 2012

2. Motivation: Belle II SVD  We can’t feed the full SVD with existing Kenwood power supplies using linear voltage regulators (as planned in TDR)   OK with DC/DC converters 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update2 1748 APV25 chips Front-end hybrids Rad-hard voltage regulators Analog level translation, data sparsification and hit time reconstruction Unified Belle II DAQ system ~2m copper cable Junction box ~10m copper cable FADC+PROC Unified optical data link (>20m) Finesse Transmitter Board (FTB) COPPER DC/DC converters

3. Introduction  General idea is similar to power grids:  transmit higher voltage at lower current to the front-end to minimize Ohmic cable loss  Please look at my slides from last B2GM for a general introduction and references  Indico Link Indico Link 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update3

4. DC/DC R&D at CERN and Aachen  DC/DC is the baseline for an upgrade of the CMS experiment  CMS and ATLAS Tracker groups have been studying the use of DC/DC converters for future S-LHC upgrade  CERN Microelectronics group is developing rad-hard DC/DC converter ASICs and air coils  Intensive tests with existing CMS Tracker modules (APV25) and rad-hard DC/DC converter prototypes at Aachen  APV25 + DC/DC work together without noise penalty!  See my previous presentation for details and references 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update4

5. ASIC: AMIS Family  Being developed since 2007  AMIS5 (final) now produced, expected back in August 2012 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update5 Efficiency vs. Iout Efficiency vs. TID 80…85%Rad-hard beyond 100Mrad Also tested: no SEB or SEGR AMIS4 measurements

6. “SM01C” CERN DC/DC Module 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update6  Final AMIS chip not yet available, but substitute is  CERN group developed a DC/DC module (SM01C) based on commercial converter chip (LTC3605) with similar performance as AMIS, but not rad-hard  Optimized design & layout  Size: 28.4 x 13.5 mm 2  Shielded air core coil  Available for tests  Chip will later be replaced by rad-hard AMIS ASIC SM01C Converter Module

7. Meeting with CERN Developers  On 23-24 April, I met Federico Faccio and Georget Blanchot, the DC/DC developers, at CERN  I got a few SM01C DC/DC modules for tests  Final module costs (very approximately, for a few hundred):  Chip ~10€, packaging ~2€, PCB ~5€, components ~5€  Shield: ?, air coil ~50€ (if made in industry)  Total per module: O(100€)  Remote voltage sensing not recommended (stability issue)  Better have slightly higher output voltage to allow cable drop  Possibility of redundancy (2 converters in parallel, 1 enabled)  To be confirmed by designers 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update7

8. Tests with SM01C DC/DC Modules  Junction box board with DC/DC converters to be placed in SVD DOCK boxes  1 and 2 bare hybrid boards (without sensors) attached for tests with 2m final cable 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update8

9. Results: Noise Comparison  Same noise within measurement precision (few %) between conventional and DC/DC powering! 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update9 Test hybrid (larger) Belle II design (smaller)

10. Results: Efficiency  Overall efficiency is 75% at Vin=10V with 2 hybrids load  4 hybrids and lower Vin @ Belle II  higher efficiency (~85%)  Anyway more than enough for SVD purposes  Additional (small) improvement possible by larger coil 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update10

11. Summary & Outlook  Belle II SVD will use DC/DC converters to power front-end  Existing Kenwood power supplies are enough for future SVD  CERN is developing rad-hard converter ASIC  Final chip expected back in August  Meanwhile: drop-in based on commercial chip  Tested successfully with APV25 hybrids  No difference in noise  Efficiency of 75% obtained at Vin=10V and 2 hybrids load  ~85% expected in final configuration  Will continue tests with full detector modules 22 July 2012M. Friedl (HEPHY Vienna): DC/DC Converter Update11