1. FP420 Low and High voltage supply
Henning E. Larsen,
INFN
29 Sep. 2006

2. Bias supply segmentation
PT1000 Temperature sensor?
HV: res +-1V, +-1uA
Cinzia: 1/20nA to 1uA, Abs max is 1mA
Voltage best up to 150V at least 100V
This is a huge dynamic range! Will require 24 bit
Damage depends on distance from the beam. Required bias voltage and current increase with radiation dose.
Pixels:50x400um
and 400x50um
Drawing: Ray Thompson

3. Functions for a superlayer supply
Superlayer consists of..
Detectors (Atlas pixel detctors),
Front-end pixel-readout (Atlas Pixelchip),
MCC,
Optical transmitters
PT1000 temperature sensor
Each superlayer should be LV +HV supplied by a separate unit=>
Electrical isolation
Redundancy
Modular servicable
Isolation implies that it will have its…
own ac-ac power transformer secondary winding and AC-DC rectifier bridge
digital communcation interface isolated
Linear regulators to have best radiation tolerance. Switch-mode regulators are much more compact but more delicate.
Remote controlled fine adjustable offset and shutdown of LV supply
Remote control of HV supply and shutdown.
Monitoring of the voltage, current and local heatsink temperature
Monitoring of the superlayer frontend temperature (PT1000 sensor)
(LHC4913 STM tol 5kGy) (2.0V and 1.6V, 5W)

4. Specifications (needs finalization)
Detectors: 4 to 5 stations of 10 planes = 5 superlayers each
High voltage
Drive per detector
U= 20 to 150V, with shutdown to 0V
I=0 to 1mA
Monitor
1V resolution (12bit), Accuracy much worse (5V)
1μA resolution (12bit), Accuracy much worse
Low voltage
Drive
U= 2.0V, U=1.6V Power<10W per station
I=0 to 1mA
Monitor
10mV resolution (8bit)
Current resolution 8 bit.

5. Location for service electronics
Until today we thought:
If the LV electronics should stay within some 20m from the detectors, there are only two possible locations (ref Daniela Macina):
Below the new cryostat, where the radiation level is estimated at about 700 Gy per year of running at full luminosity;
Below or near the adjacent magnets, where the radiation is much lower and estimated at about 15 Gy per year, but where there are already other things.
At mechanics meeting 29/9/06 we saw:
Space for service electronics.
Few meters of cable
Radiation level????
Shielding possibility?
Thierry
Space for electronics needing close proximity to detectors

6. LV+HV supply blockdiagram for one station
Candidate for the crate controller is the solution from ALICE DETECTOR CONTROL SYSTEM (DCS) PROJECT
Monitor ADC: Use of the integrated Detector Control Unit, DCUF used in the CMS central tracker for the monitoring of some embedded parameters like supply voltage and currents on the front-end read-out modules. Digital interface is I2C which only reach a few meter so the controller must be close by
Control DAC: Currently no suggestion for a DAC.
Local control: Rad tolerant FPGA from

7. LV+HV Crate for 1 station with 8 superlayers=16 hybrids=48 detectors

8. HV principle diagram V1 Ibias Vin αIbias + Vbias - Cable R3 Pass
transistor R1
R2 +R3 R2
Vin
αIbias +
Vbias -
Transformer+rectifier R1 R4
ADC’s
Galvanic
isolation
Use R4 to allow increase of α.
DAC
Simple linear regulator to make radiation tolerance easier to implement with COTS
Monitor, remote control, galvanic isaolated

9. HV current measurement
HV7800 is convenient, but unlikely to be radiation tolerant
HV MOSFET is required

10. Issues to finalize Location of support electronics in tunnel
Radiation level to expect. ”Most COTS breaks after few 100Gy”
Specification of LV and HV requirements (Volts, Currents, Stabilty, Ripple)
Communication interface module in LV supply?
Galvanic isolation method within supply modules: Optics or differential signals
Communication medium to slow control system: Fiber or cupper?
Segmentation within a superlayer.
Need for temperature monitor of FE for the cooling system. Where should it be seviced? If in the HV-LV unit, we need define a local interface with cooling
Cinzia will supply info about Atlas chips requirements.
Mimmo coordinate space location.
Post doc to make study on dose rate at fp420. Preliminary report in september.

11. Critical issues for support electronics (LV and HV)
What is the infrastructure and environement in LHC:
Location of support electronics in the tunnel
Radiation levels at these location
Suitable electronics to survive there. Most COTS breaks after few 100Gy
Temperature range: Variable from 14 to 30? degree
Data communication
To quote Scott: The infrastructure in the tunnel is critical: Where is room for service electronics, and what is the environment there?
We should look to what has LHC machine done to solve these issues for their support electronics. Posibly use their methods if appropriate. For slow control we have no problems with speed.

12. ADC’s: DCUF Detector Control Unit (CMS)
CMS central tracker for the monitoring of some embedded parameters like supply voltage and currents on the front-end read-out modules

13. Alice DCS
Alice slow control interface board.

14. Radiation tests
Using the neutron facility in Louvain together with the PMT tests
Test sessions already planned for november and for Januar. We can piggyback on this session with small volume (few liter).
But this is neutrons! Is this actually useful?

15. LV Block diagram
This shows a blockdiagram of the LV supply. Modules must be located some meters from the frontend for reasons of space and radiation protection. All electronics should support the environment in the LHCtunnel: Radiation and temperature.
The frontend supply (2.0 and 1.6V, <10W) is regulated with a linear regulator. It has remote sense to compensate for line drop. It is likely to be required to adjust the set-voltage remotely during operation. One candidate for regulator is LHC4913 STMicroelectronics. Used in Alice. For reasons of redundancy and electrical isolation, one module for each detector plane or super-plane.
Monitor ADC: Use of the integrated Detector Control Unit, DCUF used in the CMS central tracker for the monitoring of some embedded parameters like supply voltage and currents on the front-end read-out modules. Digital interface is I2C which only reach a few meter so the controller must be close by
Local processor: Some local intelligence is needed to simplify the communication and perform local house-keeping. Interface to I2C. Suggestions: FPGA’s from Actel, Atmel or micro controller from Aeroflex
Control DAC: Currently no suggestion for a DAC
Optical interface: Gigabit Optical Link (GOL) (Cern EP/MIC) is probably far to complicated to interface to, so something better has to be found
Located in shielded location some meters (3..20m) from frontend
One module per plane (superlayer?) for redundancy and noise reasons
Remote monitor of V,I and T
Remote control of deltaV and power ON/Off
Local over-temperture protection
ADC 12 bit: Use of the integrated Detector Control Unit, DCUF used in the CMS central tracker is practical.

16. Notes:
Current to voltage shunt converter: ina19X from ti.