1. SPP-COB meets a module Ashley and Peter 17 th June 2011

2. SPP-COB and M17 2

3. H0 Integral 2.5V H1 Integral 2.5V TTi 5A H0 (top) SPP-COB 2.3V H1 Integral 2.5V TTi 5A H0 SPP-COB 2.3V H1 SPP-COB 2.3V CSI 5.5A H0 SPP-COB 2.45V H1 SPP-COB 2.45V CSI 5.5A 3 iDelay Change => Column Flip

4. The Truth behind the Plots! SPP-COB in one location (low side) worked “out of the box” – As expected SPP-COB in both locations was a struggle – With TTI power supply, “low” side would not work Ramp up too slow for BCC? – With CSI power supply, “high” side would not work Clamp to ~1.6V with R4 33k, ~2.0V with R4 36k A similar “failure” mode sometimes occurs on the SP stavelet when PPB slow control bypass is disabled. – Is there a common cause? Can avoid overvoltage conditions by controlled ramping Eventually got both hybrids working with SPP-COB using following recipe – Set CSI to 4.0A, configure hybrids – Set CSI to 4.5A, configure hybrids – Set CSI to 5.0A, configure hybrids – Set CSI to 5.5A, configure hybrids – Cycle LVDS buffer power, configure Hybrids (recover BCC dclk) 4

5. Power up ramps: TTi @ 5.0A H0: BCC UNRESPONSIVE H1: BCC & ABCN WORK Diff Probe, power feed on Module Frame PCB 5

6. Power up ramps: CSi @ 5.0A H0: BCC & ABCN WORK H1: Hybrid clamps at ~1.6V (~2V on PCB) ~2.80V Diff Probe, power feed on Module Frame PCB From memory, W shunt regulates at 2.6V, with over voltage trip at ~2.7V ~2.75V 6

7. Thermal Camera Images 7 HO SPP-COB H1 SPP-SOB CSI 4A => Hot chips on both hybrids HO SPP-COB H1 op-amp/zener CSI 4A => Hot chips on H0 only

8. Discussion A mode exists, using SPP-COB, whereby one or more chips sink more current than the others – This does not occur using the usual op-amp/zener shunt controller circuit One difference here is that SPP-COB is independently powered whereas the usual circuit using commercial components is parasitically powered in parallel with the hybrid – Hybrid voltages and shunt control lines may have different behaviour during the power up ramp The Million Dollar Question: – Are the hotspots shunt M or shunt W’s over voltage protection? 8

9. Other Stuff Spi – HSIO can drive it – Not yet tested with module DC-DC Stavelet – Module still hanging on – Field and ENC measurements in progress – Lots to understand SP Stavelet – On hold pending SPP & Spi results 9