Analog Pilot Conversion

Here I will try to explain the analog pilot conversion parameters for the 16 ADC values shifted out by the jtag interface, next you see a diagram of the adc connections in the anapil :


There are two ways of calculating these values

1 If you don't have the data collected during the halfstave and mcm tests

You can approximate the corresponding voltage measured by the adc using the next formula:

Vmeasured = 1.379*adcCount + 513       (mV)

for the values read for the 6 DAC's (DAC_REF_HIGH, DAC_REF_MID, TEST_HI, TEST_LOW, GTL_REF) due to a voltage drop in the grounding of the pixel bus, a delta has to be applied. These deltas can be found in Bari's database or read from a configuration file for the corresponding half stave .

It is known that the anapil current changes from halfstave to halfstave, from the values collected by Michele Caselle during the router interlock calibration, it was found out that a good guess is 0.245

So for calculating the BUS and MCM temperatures you can use the following formulas :

Rtbus = (1.379*adcCount + 513)/0.245         (ohm)
Tbus= (Rtbus-5000)/19.25    (C)      -> pt5000 formula
Rmcm = (1.379*adcCount + 513)/0.245    (ohm)

R0=4700.00 (ohm)
T0 =298.15 (K)

Tmcm = B/( log(Rmcm/R0) + B/T0 ) - 273.15    (C)  -> NTC formula    

2 If you have the data collected during the halfstave and mcm tests

If you happen to have the data collected during the halfstave and mcm tests then you will find the next parameters:


the first 5 values are the deltas to apply for the measurements of the anapil DACS

Ipt is the measure of the current injected to measure the temperatures

ADCSenseV is an array mapping the voltage measured by the adc corresponding to a certain adc count

ADCSenseI2 is an array mapping the measurement of SenseI

ADCPixelVdd is the mapping of the VddPilot voltage to a certain adc count

so :

Vmeasure = ADCSenseV[adcCount]       (mV) 
SenseI= ADCSenseI2[adcCount]
VddPilot = 2*ADCPixelVdd[adcCount]      (mV)

Rtbus = ADCSenseV[adcCount]/Ipt (then use pt5000 formula to get the temperature, see above)
Rtmcm= ADCSenseV[adcCount]/Ipt (then use NTC formula to get the the temperature, see above)

all other values just use the corresponding voltage measured by the adc (Vmeasured = ADCSenseV[adcCount])

Topic attachments
I Attachment History Action Size Date Who Comment
Microsoft Word filedoc Calculation_of_temperatures_and_statistical_distribution_read_from_Router_for_monitoring_and_interlock.doc r1 manage 65.5 K 2008-07-03 - 20:06 CesarMatos Calculation of the temperatures doc, thanks to Michele
Microsoft Excel Spreadsheetxls SPD_temperature_calibration_final_statistical.xls r1 manage 291.5 K 2008-07-03 - 20:05 CesarMatos router temperature calibration excel sheet
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Topic revision: r3 - 2008-07-04 - CesarMatos
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