tmp89fm42k TOSHIBA Semiconductor CORPORATION, tmp89fm42k Datasheet - Page 330

• Manufacturer Part Number: tmp89fm42k
• Description: 8 Bit Microcontroller Tlcs-870/c1 Series
• Manufacturer: TOSHIBA Semiconductor CORPORATION

20.7
Precautions about the AD Converter
RA002
20.7
20.7.1
20.7.2
20.7.3
rnal resistance:
rnal capacitance:
Figure 20-5 Analog Input Equivalent Circuit and Example of Input Pin Processing
Precautions about the AD Converter
this range is applied to one of the analog input pins, the converted value on that pin becomes uncertain, and
converted values on other pins will also be affected.
to execute AD conversion, input/output instructions at all other pins (ports) must not be executed. If they are
executed, there is the possibility that the accuracy of AD conversion may deteriorate. This also applies to pins
other than analog input pins; if one pin receives inputs or generates outputs, noise may occur and its adjacent
pins may be affected by that noise.
of the analog input source, the more susceptible it becomes to noise. Therefore, make sure the output impedance
of the signal source in your design is 5 kΩ or less. It is recommended that a capacitor be attached externally.
Analog input pins (AIN0 through AIN7) should be used at voltages from VAREF to VSS. If any voltage outside
Analog input pins (AIN0 to AIN7) are also used as input/output ports. In using one of analog input pins (ports)
The internal equivalent circuit of the analog input pins is shown in Figure 20-5. The higher the output impedance
Analog input pin voltage range
Analog input pins used as input/output ports
Noise countermeasure
Note) i = 7 to 0
Permissible signal
source impedance:
5 kΩ (max)
Analog comparator
DA converter
AINi
5 kΩ (typ)
Internal resistance:
Internal capacitance:
#!Undefined!# kΩ (typ)
Page 312
C = 22 pF (typ.)
Analog comparator
DA converter
TMP89FM42K