Data Translation DT9820 Series, Руководство пользователя

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Principles of Operation
17
2
2
2
2
2
2
2
2
2
Converting an Offset Code to a Voltage
To convert an offset code into a voltage, use the following formulas:
LSB = FSR
2
N
Vin = Code * LSB + Offset
where,
• LSB is the least significant bit.
• FSR is the full-scale range. For the DT9820 Series, the full-scale
range is 2.5 for the 0 to 2.5 V range or 2.6 for the -0.10 to 2.5 V
range.
• N is the input resolution (24 bits).
• Vin is the analog voltage.
• Code is the raw count used by the software to represent the
voltage in binary notation.
• Offset is the actual minus full-scale value. The minus full-scale
value is 0.0 V for the 0 to 2.5 V rang e or
−
0.10 V for the
−
0.10 to
2.5 V input range.
For example, assume that you are using a DT9821 with a unipolar
input range of
−
0.10 to 2.5 V. If the software returns a code of C00000h
for the analog input operation, determine the analog input voltage as
follows:
LSB = 2.6 = 0.00000015497
16777216
Vin = C00000h * 0.00000
−
0.10 V
Vin = 1.85 V