Piotr Malecki Draft no 1.1 Dec. 10-th 1996 The Silicon Strip Detector Power Supplies and Distribution Requirements Document This document is a draft version of the requirements for the powering of modules of the silicon strip detector (SCT) both, in the barrel and in end cap wheels. These requirements are strongly related to the baseline design of the detector modules: two layers of single-sided strip detectors, 768 channels each, serviced by 12 amplifier/discriminator CAFE chips (every one for 128 channels) and 12 CMOS pipeline chips ABC as well as DORIC, a front-end clock and L1 distribution chip and dual LED driver circuit LDC. The requirements also apply to the DMILL option of a combined CAFE/ABC chip. 1. MODULARITY. The modularity of SCT power supplies shall follow the modularity of the detector. There shall be 3688 power supplies of required voltages (see below) to serve 2112 detector modules in four barrel layers and of 1576 modules in two end caps. Each end cap consists of nine wheels. Eight "complete" wheels are equipped with two rings of 40 and 52 modules and the ninth one with only a ring of 52 modules. 2. VOLTAGES. Modules are powered with a set of low voltages (LV) for front-end electronics: - CAFE voltage, - ABC voltage, serving also DORIC3 and LDC chips and - PIN photo-diode voltage for a photo-diode connected to DORIC input. and with - detector bias voltage, called also high voltage (HV). 3. CAFE VOLTAGE. Required parameter values are given for one detector module. All values are given on a module - if applicable. 3.1 Nominal value +3.50 V (+/- 5%) 3.2 Maximum current 1000 mA 3.3 Voltage setting resolution 0.01 V 3.4 Current monitoring accuracy 1 mA 3.5 Reaction time for voltage adjustment 100 usec 3.6 Start/stop ramping (for power reset) 2 V/s 3.7 Over-current trip at 1200 mA 3.8 Over-voltage trip at +5.50 V 3.9 Allowable noise level 35 mV 3.A On crate and inter-crate communication protocol - unspecified (CAN bus, RS485 ?) 3.B No remote sensing and feedback control 3.C Status register latching the trip cause 3.D Power supply enable line (for sequencer system) 3.E Nominal voltage setting "hardwired" into a PS 3.1 CAFE PREAMPLIFIER CURRENT CONTROL VOLTAGE (VI1). 3.1.1 Nominal value +1.00 V 3.1.2 Maximum current (0.5 mA/chip) 6.0 mA 3.1.3 Voltage setting resolution 0. 1 V 3.1.4 Over-current trip at 8.0 mA 3.1.5 Over-voltage trip at +3.50 V 3.1.6 No remote sensing and feedback control 3.1.7 Status register latching the trip cause 3.1.8 Nominal voltage setting ? 4. ABC VOLTAGE. Required parameter values are given for one detector module. All values are given on a module - if applicable. 4.1 Nominal value +4.00 V (+/- 5%) 4.2 Maximum current 500 mA 4.3 Voltage setting resolution 0.01 V 4.4 Current monitoring accuracy 1 mA 4.5 Reaction time for voltage adjustment 100 usec 4.6 Start/stop ramping unspecified 4.7 Over-current trip at 600 mA 4.8 Over-voltage trip at +6.00 V 4.9 Allowable noise level 35 mV 4.A On crate and inter-crate communication protocol - unspecified (CAN bus, RS485 ?) 4.B No remote sensing and feedback control 4.C Status register latching the trip cause 4.D Power supply enable line (for sequencer system) 4.E Nominal voltage setting "hardwired" into a PS 5. PIN VOLTAGE. Required parameter values are given for one detector module. All values are given on a module - if applicable. 5.1 Nominal value 10.00 V 5.2 Maximum current 10 uA 5.3 Voltage setting resolution 0.1 V 5.4 Current monitoring accuracy 1 uA 5.5 Reaction time for voltage adjustment unspecified 5.6 Start/stop ramping unspecified 5.7 Over-current trip at 15 uA 5.8 Over-voltage trip at ? V 5.9 Allowable noise level 100 mV 5.A On crate and inter-crate communication protocol - unspecified (CAN bus, RS485 ?) 5.B No remote sensing and feedback control 5.C Status register latching the trip cause 5.D Power supply enable line (for sequencer system) 5.E Nominal voltage setting "hardwired" into a PS 6. BIAS VOLTAGE (HV). Required parameter values are given for one detector module. All values are given on a module - if applicable. 6.1 Nominal value range 10 - 300 V 6.2 Current 4 uA - 4 mA 6.3 Voltage setting resolution 1 V 6.4 Current monitoring accuracy - multi-range 6.5 Reaction time for voltage adjustment 20 msec 6.6 Start/stop ramping unspecified 6.7 Over-current trip programmable 6.8 Over-voltage trip at 400 V 6.9 Allowable noise level 200 mV 6.A On crate and inter-crate communication protocol - unspecified (CAN bus, RS485 ?) 6.B No remote sensing and feedback control 6.C Status register latching the trip cause 6.D Power supply enable line (for sequencer system) 6.E Nominal voltage setting by digital control input 7. LOCALIZATION of PS modules. Two possibilities are considered: 1. Racks with crates of Power Supply modules shall be placed on shelves on the outer shell of the ATLAS detector. PS modules shall work in 200-400 Gs field. Access is granted during short 1-day shutdowns of the machine. 2. Racks are in the service room outside the tunnel. Besides the magnetic field and radiation the difference in distance is about 55m. 8. MUTUAL LOCALIZATION of the low voltage (LV) and high voltage (HV) power supply modules. LV and HV modules serving the same detector module should be close to each other. If designers exclude common boards then neighboring crates in the same rack should be a choice. A common patch panel should allow grouping all lines belonging to the same module in one multi-wire cable. The packing of modules of LV and HV power supplies on boards should be either identical or making the identification "crystal clear". 9. POWER DISTRIBUTION and CABLING 9.1 Modules are powered by separate two-wire lines for every voltage. All leads for a module are grouped in multi-wire cable. Low mass cables are used inside the detector space and conventional cables outside. 9.2 The length of low mass cables depends on a module location and does not exceeds 10 m. The first part of this, about 2 m, run inside the cold box of the barrel or end cap at -10 (-20?) deg. Celsius. The passage outside these boxes should be done without cutting (low mass) cables. The length of conventional cables depends on a position of PS racks. It should not exceed 25 m for the case of shelves and 80m for the other one. 9.3 Maximum voltage drop for 3.5 V CAFE voltage shall be 0.2 V in a low mass section (round-trip) and less than 0.1 V in a conventional cable. Power dissipation in low mass cable section of 0.2 W corresponds to 5.7 % of the module power consumption at 3.5 V. The corresponding cross section of aluminum leads is 2.8 mm2. 9.4 Maximum voltage drop for 4 V ABC voltage shall also be 0.2 V in a low mass section (round-trip) and less than 0.1 V in a conventional cable. Power dissipation in low mass cable section of 0.1 W corresponds to 5 % of the module power consumption at 4 V. The corresponding cross section of aluminum leads is 1.4 mm2. 9.5 Cross section of other leads of the low mass cable may be dictated by the cable technology. 9.6 Total number of leads per module is 10 including: CAFE 3.5V -- 2 ABC 4.0V -- 2 BIAS -- 2 VI1 -- 1 PIN -- 2 ABC clock enable -- 1 (2?) 9.7 Grounding scheme. Supplying each voltage with two-wire line makes a low frequency isolation of modules possible. An influence of the high frequency intensive field in the area of SCT requires simulations and test measurements allowing for the optimal scheme, cable shaping and module design. Such simulations and measurements shall be carried out in 1997. ----------------------------------------------------------------------------- ___________________________________________________________________ This mail has been sent to all members of the list atlas-sct ___________________________________________________________________