MB95120MB Series
(3) Definition of A/D Converter Terms
• Resolution
The level of analog variation that can be distinguished by the A/D converter.
When the number of bits is 10, analog voltage can be divided into 210 = 1024.
• Linearity error (unit : LSB)
The deviation between the value along a straight line connecting the zero transition point
(“00 0000 0000” ← → “00 0000 0001”) of a device and the full-scale transition point
(“11 1111 1111” ← → “11 1111 1110”) compared with the actual conversion values obtained.
• Differential linear error (Unit : LSB)
Deviation of input voltage, which is required for changing output code by 1 LSB, from an ideal value.
• Total error (unit: LSB)
Difference between actual and theoretical values, caused by a zero transition error, full-scale transition error,
linearity error, quantum error, and noise.
Ideal I/O characteristics
Total error
VFST
3FFH
3FFH
3FE
H
3FE
H
Actual conversion
characteristic
1.5 LSB
3FD
H
3FD
H
{1 LSB × (N − 1) + 0.5 LSB}
004
003
002
001
H
H
H
H
004
003
002
001
H
H
H
H
V
NT
V
OT
Actual conversion
characteristic
1 LSB
0.5 LSB
Ideal characteristics
AVSS
AVSS
AVR
AVR
Analog input
Analog input
Total error of
digital output N
AVR − AVSS
1024
VNT − {1 LSB × (N − 1) + 0.5 LSB}
=
1 LSB =
(V)
[LSB]
1 LSB
N
: A/D converter digital output value
VNT : A voltage at which digital output transits from (N − 1)H to NH.
(Continued)
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