MKL04Z32VFK4 Datasheet, PDF (461/658 Pages) Freescale Semiconductor, Inc – KL04 Sub-Family Reference Manual

Chapter 28 Analog-to-Digital Converter (ADC)
• Zero-scale error (E_ZS), sometimes called offset: This error is defined as the difference
between the actual code width of the first conversion and the ideal code width. This
is 1/2 LSB in 8-bit, 10-bit, or 12-bit modes. If the first conversion is 0x001, the
difference between the actual 0x001 code width and its ideal (1 LSB) is used.
• Full-scale error (E_FS): This error is defined as the difference between the actual code
width of the last conversion and the ideal code width. This is 1.5 LSB in 8-bit, 10-bit,
or 12-bit modes. If the last conversion is 0x3FE, the difference between the actual
0x3FE code width and its ideal (1 LSB) is used.
• Differential non-linearity (DNL): This error is defined as the worst-case difference
between the actual code width and the ideal code width for all conversions.
• Integral non-linearity (INL): This error is defined as the highest-value or absolute
value that the running sum of DNL achieves. More simply, this is the worst-case
difference of the actual transition voltage to a given code and its corresponding ideal
transition voltage, for all codes.
• Total unadjusted error (TUE): This error is defined as the difference between the
actual transfer function and the ideal straight-line transfer function and includes all
forms of error.
28.6.2.6 Code jitter, non-monotonicity, and missing codes
Analog-to-digital converters are susceptible to three special forms of error:
• Code jitter: Code jitter is when, at certain points, a given input voltage converts to
one of the two values when sampled repeatedly. Ideally, when the input voltage is
infinitesimally smaller than the transition voltage, the converter yields the lower
code, and vice-versa. However, even small amounts of system noise can cause the
converter to be indeterminate, between two codes, for a range of input voltages
around the transition voltage.
This error may be reduced by repeatedly sampling the input and averaging the result.
Additionally, the techniques discussed in Noise-induced errors reduces this error.
• Non-monotonicity: Non-monotonicity is defined as when, except for code jitter, the
converter converts to a lower code for a higher input voltage.
• Missing codes: Missing codes are those values never converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and have no missing
codes.
KL04 Sub-Family Reference Manual, Rev. 3.1, November 2012
Freescale Semiconductor, Inc.
461