Absolute accuracy: v0x-v3x, Settling time: v0x-v3x – Measurement Computing USB-TC-AI User Manual
Page 18
USB-TC-AI User's Guide
Specifications
18
Absolute accuracy: V0x-V3x
Table 5. 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 8:
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 1Meg ohm can be used for most applications.
Note 9:
All ground pins 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 10:
Unused voltage inputs should not be left floating. These inputs should be placed in the Disabled
mode or connected to GND.
Table 6. 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 7. 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 7 summarizes the noise performance for the USB-TC-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.
Settling time: V0x-V3x
Table 8. Settling time specifications
Range
Accuracy
±0.0004% (seconds)
±10 V
15.0
±5 V
0.40
±2.5 V
0.40
±1.25 V
0.40
Settling time is defined as the time required for a channel to settle within a specified accuracy in response to a
full-scale (FS) step input.