MB89656AR FUJITSU [Fujitsu Component Limited.], MB89656AR Datasheet - Page 39

• Manufacturer Part Number: MB89656AR
• Description: 8-bit Proprietary Microcontroller
• Manufacturer: FUJITSU [Fujitsu Component Limited.]

(2) Precautions
• Input impedance of the analog input pins
The A/D converter used for the MB89650AR series contains a sample hold circuit as illustrated below to fetch
analog input voltage into the sample hold capacitor for eight instruction cycles after activating A/D conversion.
For this reason, if the output impedance of the external circuit for the analog input is high, analog input voltage
might not stabilize within the analog input sampling period. Therefore, it is recommended to keep the output
impedance of the external circuit low (below 10 k ).
Note that if the impedance cannot be kept low, it is recommended to connect an external capacitor of about
0.1 F for the analog input pin.
• Error
The smaller the | AVR – AV
Analog Input Equivalent Circuit
If the analog input
impedance is higher
than 10 k , it is
recommended to
connect an external
capacitor of approx.
0.1 F.
Analog input pin
SS
|, the greater the error would become relatively.
Analog channel selector
Sample hold circuit
Close for 8 instruction cycles after activating
A/D conversion.
MB89650AR Series
C = 33 pF
R = 6 k
.
.
.
.
Comparator
39