Lucent Technologies MN102F85K User Manual

152

The type of this Analog-to-Digital Converter is a sample-hold one, and so the 

current temporarily flows in conversion to charge the condenser of the sample-
hold circuit. For this reasons, the following settings are needed to get the 

accurancy of convension:

1.

Impedance of analog input terminal must be below 8k

Ω

.

2.

When impedance of analog input terminal is over 8k

Ω

, condenser which 

capacity is above 2000 pF must be connected to suppress the voltage 

changes of the analog input terminal.

3.

During conversion do not change the output level of the terminal (from H to 
L or from L to H), and not turn on and off the peripheral circuit, cause these 

actions may influence the power supply voltage.

micro computer

analog signal output

equivalent circuit

Analog-to-Digital

     input terminal

R

C

Vss

R << 8k

Ω

      or

C 

≥ 

2000pF