Integral Linearity Error; Figure 11. Differential Linearity Error Representation - ST STM32 Application Note

ADC errors
1. The differential linearity error, E
If V
REF+
0x9B0 and 0x9B2. Similarly, for an input of 2.0014 V (0x9B3), the results may vary between
0x9B2 and 0x9B4.
As a result, the total voltage variation corresponding to the 0x9B2 step is:
0x9B3 – 0x9B1, that is, 2.0014 V – 1.9998 V = 1.6 mV (1660 µV)
= 1660 µV – 805.6 µV
E
D
= 854.4 µV
E
D
= (854.4 µV/805.6 µV) LSB
E
D
E = 1.06 LSB
D
Let us assume that no voltage greater than 2.0014 V will result in the 0x9B2 digital code
when the step width is less than 1 LSB, E
2.1.4

Integral linearity error

The integral linearity error is the maximum deviation between any actual transition and the
endpoint correlation line. The ILE is denoted by E
The endpoint correlation line can be defined as the line on the A/D transfer curve that
connects the first actual transition with the last actual transition. E
line for each transition. The endpoint correlation line thus corresponds to the actual transfer
curve and has no relation to the ideal transfer curve.
The ILE is also known as the integral non linearity error (INL). The ILE is the integral of the
DLE over the whole range.
14/49

Figure 11. Differential linearity error representation

, is shown in magenta.
D
= 3.3 V, an analog input of 1.9998 V (0x9B1) can provide results varying between
is negative.
D
. It is represented in
L
DocID15067 Rev 3
AN2834
Figure 12.
is the deviation from this
L