USB-1208FS-Plus-OEM User's Guide
Functional Details
16
Figure 9 shows an ideal, error-free transfer function. The typical calibrated accuracy is range-dependent. Refer
to the
on page 20 for more information. We use a ±10 V range here as an example of
what you can expect when performing a measurement in this range.
Figure 9. Ideal ADC transfer function
The offset error is measured at mid-scale. Ideally, a zero volt input should produce an output code of 2048. Any
deviation from this is an offset error.
Figure 10 shows an example of a transfer function with a ±9.77 mV offset error. Offset error affects all codes
equally by shifting the entire transfer function up or down along the input voltage axis.
The accuracy plots in Figure 10 are drawn for clarity and are not drawn to scale.
Figure 10. ADC transfer function with offset error
Gain error is a change in the slope of the transfer function from the ideal, and is typically expressed as a
percentage of full-scale.
