tmp89fm42 TOSHIBA Semiconductor CORPORATION, tmp89fm42 Datasheet - Page 316

• Manufacturer Part Number: tmp89fm42
• Description: 8 Bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

20.7 Precautions about the AD Converter
20. 10-bit AD Converter (ADC)
RA001
20.7 Precautions about the AD Converter
rnal resistance:
rnal capacitance:
20.7.1 Analog input pin voltage range
20.7.2 Analog input pins used as input/output ports
20.7.3 Noise countermeasure
Figure 20-5 Analog Input Equivalent Circuit and Example of Input Pin Processing
side 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.
(ports) 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.
ance 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 k: 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 out-
Analog input pins (AIN0 to AIN7) are also used as input/output ports. In using one of analog input pins
The internal equivalent circuit of the analog input pins is shown in Figure 20-5. The higher the output imped-
Note) i = 7 to 0
Permissible signal
source impedance:
5 k: (max)
Analog comparator
DA converter
AINi
5 k: (typ)
Internal resistance:
Internal capacitance:
#!Undefined!# kΩ (typ)
Page 302
C = 22 pF (typ.)
Analog comparator
DA converter
TMP89FM42