29

MB89143A/144A

6. A/D Glossary

• Resolution

Analog changes that are identifiable with the A/D converter

• Linearity error

The deviation of the straight line connecting the zero transition point (“0000 0000”

↔ “0000 0001”) with the

full-scale transition point (“1111 1111”

↔ “1111 1110”) from actual conversion characteristics

• Differential linearity error

The deviation of input voltage needed to change the output code by 1 LSB from the theoretical value

• Total error

The difference between actual and theoretical value

This error is caused by the zero transition error, full-scale transition error, linearity error, quantization error,

and noise.

1111 1111

1111 1110

0000 0010

0000 0001

0000 0000

Theoretical I/O characteristics

Analog input

1 LSB =

256

1 LSB

Linearity error =

AVR

(1 LSB

Actual conversion

value

Theoretical conversion

value

Linearity error

1 LSB

Differential linearity error =

1 LSB

Total error =

−1

− (1 LSB × N + 0.5 LSB)