1. SP & DC-DC Considering the benefits of combining serial powering and DC-DC conversion technologies in powering ATLAS SCT upgrade modules & staves Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 1

2. ATLAS now independent powering, ABCD One hybrid ABCD = A Binary Chip in DMILL-technology Digital: Analogue: ABCD (0.8  m) 4.0 volts 3.5 volts 150mA per ABCD 50mA per ABCD This wiring scheme is used on modules within the ATLAS inner detector Semi-Conductor Tracker (SCT) Independent wires are used to supply power to each hybrid Four separate powr supply conductors are used between each hybrid and cavern 2 B a c k g r o u n d Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

3. ABCD with SP serial powering tests now, ABCD One hybrid ABCD (0.8  m) Digital: Analogue: 4.0 volts 3.5 volts 150mA per ABC 50mA per ABC SR = Shunt Regulator, LR = Linear Regulator 3 B a c k g r o u n d Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

4. Comparing ABC power Digital: Analogue: ABCD (0.8  m, biCMOS) 4.0 volts 3.5 volts 35 mA per ABC measured 74 mA per ABC measured * Measured by Peter Philips => 4.0 x 35 + 3.5 x 74 = 399 milliwatts Digital: Analogue: ABC- N (0.13  m CMOS) 0.9 volts 1.2 volts 51 mA per ABC 16 mA per ABC † => 0.9 x 51 + 1.2 x 16 = 65 milliwatts Digital: Analogue: 2.5 volts 2.2 volts 95 mA per ABC measured 27 mA per ABC measured => 2.5 x 95 + 2.2 x 27 = 300 milliwatts ABC- N (0.25  m CMOS) Ignoring local power conversion & delivery cable losses Options for powering are discussed in the next slides Notice that for 0.13  m ABC- N: Analogue voltage is higher than digital requirement …And analogue draws a lower current Question: How do we cope with a higher analogue voltage? In ATLAS now Manufactured now Proposed ** Ref http://indico.cern.ch/getFile.py/access?contribId=16&sessionId=8&resId=0&materialId=slides&confId=32084http://indico.cern.ch/getFile.py/access?contribId=16&sessionId=8&resId=0&materialId=slides&confId=32084 Power consumed per ABC per channel * * 3.1 milliwatts 2.3 milliwatts 0.5 milliwatts 4 ** B a c k g r o u n d Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

5. Definition – Hybrid (excludes stave interconnects & supply cables) Efficiency = H power delivered to hybrid power consumed by ABC- N Definition – Detector (includes all supply cables within the detector cavern) Efficiency = D power delivered by power supply power consumed by ABC- N And we will assume: SR = 85%, low current DC-DC = 90%, high current DC-DC = 85% 5 The ABC demand power is dependant on task. This will normally mean a shunt regulator will dissipate some power to maintain voltage under all conditions. Efficiency - definitions Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Efficiency D H

6. Analogue & digital power Selection How do we decide what’s best? – Selection Criteria This should be based upon Power efficiency (efficiency ) within the hybrid Power efficiency of stave (ie whole inner detector) Power efficiency (efficiency ) within the whole detector Electronic noise generated and susceptibility of detector to that noise Mass / radiation length of components used – including cables Physical issues, both inside and outside the Inner Detector: Dimensions, materials, environment (radiation tolerance, operating temperature & fluctuations, aging, gas, magnetic field) And other issues unlikely to have an influence… Installation issues Practicality of supplying power to the detector at necessary voltage/current Cost And we will assume: SR = 85%, low current DC-DC integer = 90%, fractional = 80%, high current DC-DC = 85% 6 The ABC demand power is dependant on task. This will normally mean a shunt regulator will dissipate some power to maintain voltage under all conditions. H D Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

7. Lots of circuit options (1) 7 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Note: voltages not as spec 1 2 3 4 5 6

8. 8 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion …these options ignore the possibility of generating HV bias within each hybrid… Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Independent powering Parallel powering DC-DC favoured option 3:1 & 4:1 DC-DC SP & 3:1 & 4:1 DC-DC 10 11 7 8 9 Lots of circuit options (2)

9. 9 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 12 13 Lots of circuit options (3)

10. Efficiency How do these options compare? 10 Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

11. Comparing hybrid efficiency 11 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Eff = 69% Eff = 61% D H Eff = 55% Eff = 50% D H Eff = 78% Eff = 73% D H Eff = 80% Eff = 65% D H Eff = 71% Eff = 59% D H D H 1 2 3 4 5 6

12. More circuit options 12 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Highest efficiency Eff = 76% Eff = 40% D H Eff = 100% Eff = 1% D H Eff = 77% Eff = 75% D H Eff = 90% Eff = 14% D H Eff = 100% Eff = 1% D H 7 8 9 10 11

13. More circuit options 13 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Eff = 79% Eff = 67% Eff = 72% Eff = 65% 12 13 D H D H

14. Efficiency observations 14 1.Higher voltage supply lines increase Efficiency 2.Serial powering allows higher voltage supply lines 3.Serial powering: Efficiency is dominated by Efficiency at higher supply voltages 4.Independent or parallel powering would require a much lower supply cable resistance to be viable options Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 DH D

15. Favoured options 15 SR = Shunt Regulator, LR = Linear Regulator, DC-DC = DC to DC voltage conversion Highest efficiency No DC-DC Lowest noise DC-DC favoured option Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Eff = 55% Eff = 50% D H Eff = 76% Eff = 40% D H Eff = 77% Eff = 75% D H 11 2 7

16. Conclusion Combining serial powering and DC-DC techniques appears to be a promising option if noise and other issues are acceptable 16 …but other issues affecting the selection of a powering method must be addressed too… Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

17. 17 Supplemental slides Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008

18. Analogue & digital power Practical options Efficiency 0.85 x 65mW / (1.2volts x 51mA + 1.2volts x 16mA) = 0.69 69% H Efficiency 0.85 x 65mW / (1.5volts x 51mA + 1.5volts x 16mA) = 0.55 55% H 18 SR = Shunt Regulator, LR = Linear Regulator Simple implementation, low noise Simple implementation and very low noise Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Numbers rounded 1 2

19. Analogue & digital power Practical options Efficiency 0.85 x 65mW / (0.8volts x 51mA / 0.9 + 1.6volts x 16mA) = 0.78 78% H Efficiency 0.85 x 65mW / (0.8volts x 51mA + 1.6volts x 16mA / 0.9) = 0.80 80% H 19 SR = Shunt Regulator, DC-DC = DC to DC voltage conversion Simple implementation, low noise Higher supply voltage means lower cable losses Simple implementation and very low noise Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Numbers rounded 3 4

20. Analogue & digital power Practical options Efficiency 0.85 x 65mW / (0.9volts x 51mA + 1.8volts x 16mA / 0.9) = 0.71 71% H Efficiency 0.85 x 65mW / (0.9volts x 51mA + 0.9volts x 32mA / 0.9) = 0.71 71% H 20 SR = Shunt Regulator, DC-DC = DC to DC voltage conversion LR analogue to reduce DC-DC noise As above, but changed order of LR & DC-DC Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Numbers rounded 5 6

21. Analogue & digital power Efficiency 0.85 x 65mW / (0.9volts x 51mA / 0.9 + 1.2volts x 16mA / 0.9) = 0.77 77% H *** This is the DC-DC favoured option *** 21 DC-DC = DC to DC voltage conversion Noisy? Cable efficiency? Independent powering for comparison DC-DC favoured option for comparison Efficiency 100% (no regulators) H … But very inefficient in supply cables Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Numbers rounded 7 8

22. Analogue & digital power Practical options Efficiency 65mW / (0.9volts x 51mA/0.9 + 1.2volts x 16mA / 0.9) = 0.90 78% H Efficiency 0.85 x 65mW / (0.9volts x 51mA/0.9 + 1.2volts x 16mA / 0.9) = 0.77 77% H 22 SR = Shunt Regulator, DC-DC = DC to DC voltage conversion High voltage Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Numbers rounded 11 10

23. Analogue & digital power Practical options Efficiency 0.85 x 65mW / (0.9volts x 51mA / 0.8 + 1.2volts x 16mA) = 0.72 72% H Efficiency 0.85 x 65mW / (0.9volts x 51mA + 1.2volts x 16mA / 0.8) = 0.79 79% H 23 SR = Shunt Regulator, DC-DC = DC to DC voltage conversion Simple implementation, low noise Higher supply voltage means lower cable losses Simple implementation and very low noise Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 Numbers rounded 12 13

24. Independent powering (100% hybrid efficiency) 24 1 stave = 24 hybrids = 480 ABC- N (0.13  m) 32 Watts 0 Watts 3 Watts Numbers rounded 2668 Watts Efficiency = 1% D Power (voltage) 2633 Watts Independent supplies (line pairs) for digital and analogue power. Same amount of copper => Cables are 96 ohms total for each line pair. Each line pair carries 20 x 51mA (digital) and 20 x 16mA (analogue). Detector power efficiency Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 8

25. Serial powering a stave, (no DC-DC version) 25 1 stave = 24 hybrids = 480 ABC- N (0.13  m) Numbers rounded Power (constant current) Regulator power = (1/eff - 1) x ABC power H Stave supply current = (32 + 14 + 0.5)watts / (1.2volts x 24) = 1.6amps Detector power efficiency 32 Watts 14 Watts 0.5 Watts Cables assumed to be 2 ohms total for each power line pair (69% efficiency ) H 5.2 Watts 52 Watts Efficiency = 61% D Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 1

26. Detector power efficiency Two-stage DC-DC powering 26 1 stave = 24 hybrids = 480 ABC- N (0.13  m) 32 Watts 9.6 Watts 1.3 Watts Numbers rounded Power (voltage) Cables assumed to be 2 ohms total for each power line pair (76% efficiency ) H Regulator power = (1/eff - 1) x ABC power Stave supply current = (32 + 9.6 + 1.3)watts / 10volts = 4.3amps 80 Watts Efficiency = 40% D 37 Watts Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 7

27. Serial powering 3.6V, 3:1 & 4:1 DC-DC 27 1 stave = 24 hybrids = 480 ABC- N (0.13  m) Numbers rounded Power (constant current) Regulator power = (1/eff - 1) x ABC power H Stave supply current = (32 + 9.6 + 0.5)watts / (3.6volts x 24) = 0.49amps Detector power efficiency 32 Watts 9.6 Watts 0.5 Watts Cables assumed to be 2 ohms total for each power line pair (77% efficiency ) H 0.5 Watts 43 Watts Efficiency = 75% D Richard Holt – Rutherford Appleton Laboratory Combined SP & DC-DC powering options December 2008 11