1. FED Temperature Measurements: Greg Iles31 March 20041 FED temperature measurements –Will components on FED exceed operating temperature in CMS? Analogue OptoRx < 70°C Differential Buffer < 85°C ADC < 85°C –Need to emulate conditions we will have in CMS –LHC crate. All measurements adjusted for intake air at 18°C. –3 FEDs placed next to each other in crate. The 2 external FEDs restrict airflow and mimic to some extent heating from crate of FEDs –1 FT Ensemble used to drive all FED channels with 100kHz frames.

2. FED Temperature Measurements: Greg Iles31 March 20042 Position of temperature sensors Analogue OptoRx 0 ADC Differential buffer Analogue OptoRx 1 Analogue OptoRx 2 Not visible.... Built in FED OptoRx temperature sensor is on opposite side of the PCB

3. FED Temperature Measurements: Greg Iles31 March 20043 Temperature of ADCs & Buffers –The following have temperature range of -40 to +85 °C ADC (AD9218) Differential buffer (EL2140) –Predicted temperature in CMS by: Measuring temperature between 2 thermocouples –One in air flow below crate –One attached to top of component with araldite (near top of FED – i.e. where it gets hot) –Added expected air temperature from heat exchanger (18 °C). –Measured devices twice. All values with 2 °C. Worst case shown. –Nominal fan speed of LHC crate = 3000rpm

4. FED Temperature Measurements: Greg Iles31 March 20044 Temperature of Opto Receivers

5. FED Temperature Measurements: Greg Iles31 March 20045 Caveats –Assume heat exchanger can provide air at 18 °C. We will place a large amount of power in localised region of heat exchanger. –100kHz, “typical” frames that I have used match those in CMS. –AOH driving minimum laser signal necessary for link (i.e. keeping power dissipation in experiment to minimum) –FED in scope mode, 6 samples and delivering data to s-link oblivion. –Only have 1 FED either side if FED under test and left hand side FED is at only ~70% power. –Can we achieve a fan speed of 3480 rpm in a CMS rack. FEDs will provide a greater impedance to the air flow, but there will be more fans. How well is fan speed correlated to air flow? Heat Exchanger Hot Warm Cold FED Analogue FED Analogue