Development of µHV miniature HV supplies Harry van der Graaf, Henk Groenstege, Fred Hartjes and Jaap Kuijt RD51 Mini workshop CERN, 24 September 2009

Why developing HV power supplies? uPutting dedicated HV units in the vicinity of a detector lAvoiding long HV cabling uCommercially available HV supplies are not suited for this lOften too bulky lMay use iron based transformers n=> do not operate in a magnetic field lNot radhard lMostly designed to deliver substantial power (1 W or more) where powers in the mW region are needed lMostly no trip level in the nA region uNeed for dedicated HV supplies for HEP detectors 2

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Concept uAs small as possible uLimited output power uSmall input power (< few mW idle mode) uVery radhard (until 1000 Mrad, 10 7 Gy) uMinimal noise emittance uOutput voltage stabilization, low ripple uHigh resolution current measurement (< 1 nA resolution) uAdjustable trip level in the nA region uExternal communication like at CAN bus 3

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Two designs for different applications 1.Larger unit, but easy to operate lSmall scale physics experiments (lab, test beams) lIn progress: lab version 50 – 500V nSHV out 2.“As small as possible” unit for big scale HEP experiments (LHC) nPlanned: Atlas upgrade: miniature and radhard version 50 – 1000V uAlso two power versions foreseen a)few mW for MPGDs and diamond b)Up to few 100 mW for silicon 4

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Lab version under development 5 uIntended specs l50 V < V out < 500 V, SHV connector lI max ≈ few µA lVoltage control by 14 bit DAC lSPI/CAN controller per board providing: nAdjustable software trip nAdjustable upward ramping speed nRapid downward ramping lCurrent measurement with 1 nA resolution or better n14 bit ADC 80 mm 110 mm

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Creating HV with Cockroft-Walton circuit u50 V block pulses in (duty cycle modulation) uNo transformer uVoltage divider feedback for stabilisation 6 Voltage feedback We cannot regulate down to 0V

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes PID circuit uSimulated operation lFETs represented by switches 7 Voltage feedback Overshoot prevention

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Current measurement uDone in HV line uUsing MEMS technology power converters l=> current measurement at high common mode voltage 8 Circuits at HV out voltage Digital communication Power level shift

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Present prototype PCB u110 x 80 mm 9 SPI/ CAN controller

RD51 Mini workshop, CERN, September 24, 2009Fred Hartjes Finally intended geometry of lab version uPractical and rugged mechanical box u136 x 82 x 40 mm 3 ufor future PCB 10 Intended dimensions µHV box Lab version