1. Tullio Grassi ATLAS–CMS Power Working Group 31 March 2010 DC-DC converters and Power Supplies requirements for CMS HCAL Phase 1 Upgrade

2. Data Fibers From the existing system to the Phase-1 upgrade, the channel count will increase ~4 times The power consumption will increase almost of the same factor. Plans to keep mechanics and cooling infrastructure Need for power efficiency  switching regulators 2 ADC ASIC Serializer Laser Driver and Laser Overview of CMS HCAL Front-end Readout Module 5V3.3V 1.5V 2.5V FPGA

3. 3 Mechanics of CMS HCAL Front-end (proposal for upgrade) ADC Cooling by contact with metal box. Metal is water cooled. ~50 mm ~85 mm 64 channels ~7 regulators Power ~45 W. ~110 mm

4. Step-down (buck) regulator: Four different versions with outputs at: 5V, 3.3V, 2.5V, 1.5V. Input up to 10V + SAFETY MARGIN Rad-hard (below tracker levels) Magnetic field 4 Tesla Efficiency: as close to 85% as possible. Max current: 3A (*) Enable input Power_good output Low noise (compatible with system susceptibility). The physical size is to be defined, but something like 30x20x10 mm 3. Package: possibly compatible with pick-and-place machines. Total quantity ~ 5000. (*) If a higher current is required, we understand that more R&D is needed 4 } together they allow power sequences Switching Regulators for HCAL: requirements

5. 5 The R&D work from the CERN MIC group (G. Blanchot, F. Faccio, et al.) is close to our needs. We are discussing with the MIC group if and how they can provide us the regulators (mezzanine with ASIC). Schedule for the HCAL front-end: Receive regulator prototypes: summer 2010 Production and test of HCAL regulators:2012 Production of full-system:2013 Burn-in tests of full system:2014 Ready to install full system: end 2014 Switching Regulators for HCAL: plans

6. 6 To our knowledge, the upgraded HCAL front-end will be one of the first HEP systems to use switching regulators, in a similar scale and environment. We should do some failure analysis at system level: Interaction between regulators (related to their frequency, etc) ? Drift of voltage output over time, after a certain dose, combined with drifts of the loads ? Switching Regulators for HCAL: concerns

7. Power Supply HCAL FE READOUT BOX R CABLE VOVO VLVL I Given: Voltage of the Load = Input of the regulator = V L = 10V Resistance of cable = R = 0.25 Ohm (worst case) Power to the box = P = 200 W (cooling limit) Then : P = V L x I; I = P / V L = 20A Voltage Output of PS = V O = V L + RI = 10 + 5 = 15V  spec for the PS Power supplied by PS = V O x I = 300 W  spec for the PS Safety margins: to protect from variations (PS output, resistance of cable, connections) we need a safety margin at the regulator input. DC-DC regulators 7 Power Budget of HCAL FEE

8. 8 Power per channel > 300 W (*) Output Voltage > 15V Input Voltage = possibly 48 V (from CAEN MAO) Current > 20 A Rad-hard ? Magnetic field: compatible with CMS cavern (outside the solenoid) Noise ? The physical size is to be defined, but similar to CAEN Easy crates. Quantity: ~ 170 channels (*) we can consider having this power delivered by 2 channels External Power Supplies for HCAL: requirements

9. External Power Supplies for HCAL: plans Other than considering commercial solutions, we are also considering to develop the Power Supplies in collaboration with other institutes or subsystems. Collaborators Welcome ! 9