mb95f108aspfv Fujitsu Microelectronics, Inc., mb95f108aspfv Datasheet - Page 59

• Manufacturer Part Number: mb95f108aspfv
• Description: 8-bit Proprietary Microcontrollers
• Manufacturer: Fujitsu Microelectronics, Inc.

(2) Notes on Using A/D Converter
• About the external impedance of analog input and its sampling time
• About errors
• Analog input equivalent circuit
• The relationship between external impedance and minimum sampling time
• A/D converter with sample and hold circuit. If the external impedance is too high to keep sufficient sampling
As |AVR − AV
Analog input pin
Note : The values are reference values.
time, the analog voltage charged to the internal sample and hold capacitor is insufficient, adversely affecting
A/D conversion precision. Therefore, to satisfy the A/D conversion precision standard, consider the relationship
between the external impedance and minimum sampling time and either adjust the register value and operating
frequency or decrease the external impedance so that the sampling time is longer than the minimum value.
Also, if the sampling time cannot be sufficient, connect a capacitor of about 0.1 µF to the analog input pin.
(External impedance = 0 kΩ to 100 kΩ)
100
90
80
70
60
50
40
30
20
10
0
0
SS
| becomes smaller, values of relative errors grow larger.
Minimum sampling time [µs]
5
During sampling : ON
10
15
AV
CC
20
AV
≥ 2.7 V
CC
25
≥ 1.8 V
30
35
R
40
2.7 V ≤ AV
1.8 V ≤ AV
C
CC
CC
≤ 3.6 V
< 2.7 V
(External impedance = 0 kΩ to 20 kΩ)
Comparator
20
18
16
14
12
10
8
6
4
2
0
0
Minimum sampling time [µs]
1.7 kΩ (Max)
84 kΩ (Max)
MB95100A Series
1
R
AV
2
CC
14.5 pF (Max)
25.2 pF (Max)
≥ 2.7 V
3
C
4
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