Data Translation DT3152-LS, User Manual

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Principles of Operation
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Step 3. Apply the Reference
Using the equation reference = gain (Vmax + offset), with the offset
equal to 0.4032 V, V
max
equal to 1.1 V, and the gain equal to 0.5,
reference is determined as follows:
reference = 0.5 (1.1 V+ 0.4032 V)
reference = 0.7516 V
Since the voltage increment for reference is 5000 µV and you want the
reference as close to 0.7516 V (751600 µV) as possible, calculate the
best fit for reference based on a step of 50 0 0µV, using the following
equations:
751600 µV / 5000 µV = 150.32 µV// 150 (round to nearest whole
number)
150 µV * 5000 µV = 750000 µV // multiply for actual reference
reference = 0.75 V
Values greater than 0.75 V are digitized to white. Figure 6 shows the
effect of using a reference value of 0.75 V, a gain value of 0.5, and an
offset of 0.4032. The DT3152-LS board can now digitize the entire
video signal from
−
0.4 V to 1.1 V, relative to the camera output.