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Serial Power Overview

Serial Power Overview. Presented by David Nelson djn@slac.stanford.edu. Serial Power. Serial power is a viable option but… Must be evaluated on a system by system basis. There are always advantages and disadvantages for different solutions Must consider in all cases

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Serial Power Overview

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  1. Serial PowerOverview Presented by David Nelson djn@slac.stanford.edu

  2. Serial Power • Serial power is a viable option but… • Must be evaluated on a system by system basis. • There are always advantages and disadvantages for different solutions • Must consider in all cases • Grounding and shielding • System stability • Noise performance • Segmentation • Reliability • Transmission line integrity • Several high speed protocols use AC coupling • CML, LVDS, etc

  3. Serial Power Example Shunt regulator Series Regulator Current Regulated Power Source Two of N Hybrids In series

  4. Six-module stave (finished; LBNL/RAL) Interface PCB Cooling hoses with connector Module 0 Module 1 Hybrid 2 Module 3 Module 4 Module 5 • -operating reliably with multi-drop control/command cables • -Low noise despite some compromises • -Can run from a single HV line

  5. 30-module stave (LBNL) • might become the largest serial powering stave ever built • so far looking very good in terms of SP 6-chip hybrid with SP on 3 cm long silicon sensors 4 V x 30 hybrids = 120 V (0.8 A) In future systems: 1.5 V x 20 hybrids = 30 V Chain of 30 hybrids is working fine Module stave is being built up

  6. Serial Power Advantages (1) • Reduced cabling • Currents are reduced significantly • Component requirements such as connectors and pins are reduced. • Smaller volume of services • Smaller cables & connectors • Reduced Radiation length • Smaller wire gauge cables • Less PWB copper for power distribution • More reliability • Less demand for high current connections • Better power efficiency • Lower currents • Doesn’t require switching power supply located near the preamplifiers and detectors.

  7. Serial Power Disadvantages (1) • Little/no experience in physics communities. • Must AC couple or use fiber communications. • Must maintain enough DC balance • Insure that data ALWAYS has enough transitions to recover data • Use 8b-10b or other encodings schemes. • Need to consider coupling capacitors’ stored energy. • Ensure that power up, power down, and fault conditions don’t destroy electronics. • Minimize coupling capacitor sizes. • Should include ground fault circuitry • You want all of the current going through the intended electronics and not taking a short cut. • Sections of electronics are tens of volts from detector grounds.

  8. Serial Power Disadvantages (2) • High voltage biasing may present issues • Detectors will see different biasing if using a common external HV source • Could develop HV locally on the serially powered section • Not all that easy developing clean HV without iron core inductors. • An open could occur that acts much like the series Christmas tree light failure.

  9. Conclusions • Need to take a close look at requirements to see if serial power is appropriate. • Serial power can work. • We have some operational experience at LBNL on silicon strip detectors. (slide 5) • No hybrids broke during many power cycles to date • Noise performance is good. • AC coupling of LVDS works.

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