Data Translation DT3152-LS, Руководство пользователя

Страница: 31 / 214

Principles of Operation
15
2
2
2
2
2
2
2
2
2
Step 1. Adjust the Offset
To digitize the data below 0.0 V, shift the signal up by setting the
offset to
−
V
min
. In our example, V
min
=
−
0.4 V; therefore,
−
V
min
= 0.4 V.
Since the voltage increment for offset is 8400 µV and you want an
offset as close to 0.4 V (400000 µV) as possible, calculate the best fit
based on a step of 8400 µV, using the following equations:
400000 µV / 8400 µV = 47.62//48 (round to nearest whole
number)
48 * 8400 µV = 403200 µV // multiply for actual offset
offset = 0.4032 V
Figure 4 shows the effect of using an offset of 0.4032 V.
Figure 4: Use of Offset Voltage
−
0.5 V
0 V
0.5 V
1.0 V
1.5 V
2.0 V
Signal with offset = 0.4 032 V
Original signal with offset = 0 V