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Talk during collaboration meeting - Ben Reese

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Power Estimation

Ben Reese (10/9/2013)

As mentioned on the SVT DAQ meeting on Friday, I’d like to get some new worst case current estimates for DVDD, AVDD and V1_25 on the Hybrids.
The current numbers I’ve been designing towards are:
 
AVDD – 1.455A Max, 0.690 Nom, 0.420 Meas
DVDD – 1.455A Max, 0.690 Nom, 0.260 Meas
V1_25 – 0.825A Max, 0.325 Nom, 0.320 Meas
 
The max numbers seem rather high relative to the others.
 
I’ve completed the analog power calculations based on Max, Nominal and Measured Hybrid currents above:
 
Max – 18.2W
Nom – 12W
Meas – 9.5W
 
If I rework the design a bit (with lower dropout LDOs) I can shave off about 2W in the “nominal” case and 4W in the “max” case.
 
One thing to note: The Front End FPGA monitors all the hybrid currents and voltages. It could be programmed to automatically power down a hybrid if the power draw reached a certain threshold. The regulators on the board can handle the “max” hybrid currents, but we probably shouldn’t let them run that high for more than a few minutes.