mc9s08qg8 Freescale Semiconductor, Inc, mc9s08qg8 Datasheet - Page 139

• Manufacturer Part Number: mc9s08qg8
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

9.6.2.6
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 very 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 range is normally around 1/2
reduced by repeatedly sampling the input and averaging the result. Additionally the techniques discussed
in
Non-monotonicity is defined as when, except for code jitter, the converter converts to a lower code for a
higher input voltage. Missing codes are those values which are never converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and to have no missing codes.
Freescale Semiconductor
Section 9.6.2.3
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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 therefore includes all forms of error.
Code Jitter, Non-Monotonicity and Missing Codes
will reduce this error.
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 1.01
LSB
and will increase with noise. This error may be
Analog-to-Digital Converter (S08ADC10V1)
139