MB90540/540G/545/545G Series
(Continued)
Linearity error
Differential linearity error
Theorential characteristics
3FF
Actual conversion
value
3FE
3FD
N + 1
{1 LSB × (N − 1) + VOT }
Actual conversion value
VFST
(measured value)
N
VNT
004
003
002
001
V (N + 1) T
Actual conversion
characteristics
(measured value)
N − 1
N − 2
VNT (measured value)
Theoretical
characteristics
Acturel conversion
value
(measured value)
VOT
AVRL
AVRH
AVRL
AVRH
Analog input
Analog input
Linearity error of
digital output N
VNT − {1 LSB × (N − 1) + VOT}
=
[LSB]
1 LSB
Differential linearity error
of digital N
V (N + 1) T − VNT
=
− 1 LSB [LSB]
1 LSB
VFST − VOT
=
1 LSB
[V]
1022
VOT : Voltage at transition of digital output from “000H” to “001H”
VFST : Voltage at transition of digital output from “3FEH” to “3FFH”
• Notes on Using A/D Converter
Select the output impedance value for the external circuit of analog input according to the following conditions, :
• Output impedance values of the external circuit of 15 kΩ or lower are recommended.
• When capacitors are connected to external pins, the capacitance of several thousand times the internal
capacitor value is recommended to minimized the effect of voltage distribution between the external capacitor
and internal capacitor.
Note : When the output impedance of the external circuit is too high, the sampling period for analog voltages may
not be sufficient (sampling period = 4.00 µs @machine clock of 16 MHz) .
• Equipment of analog input circuit model
Comparator
3.2 kΩ Max
Analog input
30 pF Max
• Error
The smaller the | AVRH − AVRL |, the greater the error would become relatively.
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