FAST ComTec MCA4A, User Manual

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Hardware Description
3.2.2 Changing the Input range
The full scale voltage range is jumper selectable between 2.0V, 2.5V, 8.0V and 10.0V (default).
The default setting is 10 V corresponding to a VPP value of 11019 (mV) for the full 16 bit range 0..65535.
This value can be edited in the ADC settings, if the “advanced Settings” checkbox is crossed, see Fig. 4.11.
Standard values for the 8 V, 2.5 V and 2 V ranges are 8875, 2640 and 2120. Enter the new VPP value if you
have changed the input range and save it. You can do a precise calibration of VPP if you connect a DC
voltage U to the input that you measure by a good digital voltmeter and get the corresponding value V(U) by
clicking the “Get Zero” button. The VPP value is then
VPP = U * 65535 / (V(U) – V(0)).
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Fig. 3.3: Simplified analog input and ADC circuitry
Fig. 3.2: Left: jumper setting for different input ranges, right: jumper positions