OM-USB-TEMP-AI User's Guide
Specifications
27
Absolute Accuracy: V0x-V3x
Table 9. Calibrated absolute accuracy specifications
Range
Absolute Accuracy
(mV)
±10 V
±2.779
±5 V
±1.398
±2.5 V
±0.707
±1.25 V
±0.362
Note 15:
When connecting differential inputs to floating input sources, the user must provide a ground
return path from each differential input to ground. To do this, simply connect a resistor from each
of the differential inputs to GND. A value of approximately 1 Meg ohm can be used for most
applications.
Note 16:
All ground pins on the OM-USB-TEMP-AI (pins 9, 19, 22, 27, 30, 33, 36, 39, 49) are common
and are isolated from earth ground. If a connection is made to earth ground when using both
voltage inputs and conductive thermocouples, the thermocouples are no longer isolated. In this
case, thermocouples must not be connected to any conductive surfaces that may be referenced to
earth ground
Note 17:
Unused voltage inputs should not be left floating. These inputs should be placed in the Disabled
mode or connected to GND.
Table 10. Accuracy components. All values are (±)
Range
Gain error
(% of reading)
Offset
error
(µV)
INL error
(% of range)
Gain
Temperature
Coefficient
(ppm/°C)
Offset Temperature
Coefficient
(µV/°C)
±10 V
0.0246
16.75
0.0015
3.68
0.42
±5 V
0.0246
16.75
0.0015
3.68
0.42
±2.5 V
0.0246
16.75
0.0015
3.68
0.42
±1.25 V
0.0246
16.75
0.0015
3.68
0.42
Table 11. Noise performance specifications
Range
Peak to peak noise
(µV)
RMS noise
(µVrms)
Noise-Free resolution
(bits)
±10 V
41.13
6.23
19.09
±5 V
30.85
4.67
18.51
±2.5 V
17.14
2.60
18.36
±1.25 V
11.14
1.69
17.98
Table 11 summarizes the noise performance for the OM-USB-TEMP-AI. Noise distribution is determined by
gathering 1000 samples with inputs tied to ground at the user connector. Samples are gathered at the maximum
specified sample rate of 2 S/s.
