IXXBB1 Fujitsu Microelectronics, Inc., IXXBB1 Datasheet - Page 120

• Manufacturer Part Number: IXXBB1
• Description: 32-bit Proprietary Microcontroller Cmos Fr60 Mb91301 Series
• Manufacturer: Fujitsu Microelectronics, Inc.

120
MB91301 Series
About the external impedance of the analog input and its sampling time
• A/D converter with sample and hold circuit. If the external impedance is too high to keep sufficient sampling
• To satisfy the A/D conversion precision standard, consider the relationship between the external impedance
• If the sampling time cannot be sufficient, connect a capacitor of about 0.1 F to the analog input pin.
• About errors
As |AVRH
Analog input equivalent circuit
The relationship between the external impedance and minimum sampling time
time, the analog voltage charged to the internal sampling and hold capacitor is insufficient, adversely affecting
A/D conversion precision.
and minimum sampling time and either adjust the resistor value and operating frequency or decrease the
external impedance so that the sampling time is longer than the minimum value.
Note : The values are reference.
Analog input
(External impedance
100
90
80
70
60
50
40
30
20
10
0
0
AV
SS
Minimum sampling time ( s)
MB91302A
| becomes smaller, values of relative errors grow larger.
5
10
15
During sampling : ON
20
0 k to 100 k )
25
30
35
R
MB91302A
C
(External impedance
20
18
16
14
12
10
8
6
4
2
0
0
1
Minimum sampling time ( s)
MB91302A
2
8.1 k (Max) 10.0 pF (Max)
3
Comparator
R
4
0 k to 20 k )
5
6
7
C
8