AN3137 datasheet(16/42 Pages) STMICROELECTRONICS

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ADC errors

AN3137

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Doc ID 16983 Rev 3

ADC errors

3.1

Introduction

This section lists the main errors which have an effect on A/D conversion accuracy. These

types of error occur in all A/D converters and conversion quality depends on eliminating

them. Values for these errors are specified in the ADC characteristics section of the

STM8L/STM8AL device datasheets. The datasheets also include sections describing

sources of error or methods for minimizing them.

3.2

Linearity errors

3.2.1

Differential nonlinearity

Differential nonlinearity (DNL) shows how far a code is from a neighboring code. The

distance is measured as a change in input voltage magnitude and then converted to LSBs.

Good ADC performances are specified as “no missing codes”. This means that if the input

voltage is swept over its range, all output code combinations will appear at the converter

output. A DNL error of <±1 LSB guarantees no missing codes. With a DNL equal to -1 LSB,

the ADC does not guarantee to have no missing codes. With a DNL greater than -1, the

device has missing codes.

Figure 7.

DNL: no missing codes

AN3137 Datasheet(PDF) 16 Page - STMicroelectronics