K60P100M100SF2RM Datasheet, PDF (852/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Application information
For 16-bit conversions, the code transitions only after the full code width is present, so
the quantization error is -1 LSB to 0 LSB and the code width of each step is 1 LSB.
34.6.2.5 Linearity errors
The ADC may also exhibit non-linearity of several forms. Every effort has been made to
reduce these errors, but the system designers should be aware of them because they affect
overall accuracy. These errors are:
• 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 (1/2 LSB in 8-bit, 10-bit, or 12-bit modes and 1 LSB in 16-bit mode). 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 (1.5 LSB in 8-bit, 10-bit, or 12-
bit modes and 1 LSB in 16-bit mode). 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 the (absolute
value of 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.
34.6.2.6 Code jitter, non-monotonicity, and missing codes
Analog-to-digital converters are susceptible to three special forms of error. These are
code jitter, non-monotonicity, and missing codes.
Code jitter is when, at certain points, a given input voltage converts to one of 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.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
852
Freescale Semiconductor, Inc.