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R01UH0336EJ0102 Rev.1.02
Page 1345 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 23 A/D Converter
23.5 Usage Notes
23.5.1
Range of Channel Input Voltage
Caution
The input voltage to the ADCAnIm pin should be within the specified voltage
range. If the channel input voltage is above AV
DD
or below AV
SS
, the
conversion result value of the channel is saturated and it may affect the electric
characteristics of the other channels.
23.5.2
Stopping Conversion Operation
Writing 0 to ADCAnCTL0.ADCAnCE during conversion operation stops the
operation and the conversion result is not stored in ADCAnCmCR.
23.5.3
Restrictions on Using Channel Sample and Hold Function
Refer to Section 23.3.12 (2), Restrictions when Using Sample and Hold
Function.
23.5.4
Application Design Notes
(1)
Analog Input Pin (ADCAnIm)
(a) The input voltage to the ADCAnIm pin should be within the specified
voltage range. In order to avoid input of the voltage equal to or above
AV
REFnP
or equal to or below AV
REFnM
, the input voltage is recommended
to be clamped with a diode with a 0.3-V or less V
F
. If the voltage equal to or
above AV
REFnP
or equal to or below AV
REFnM
is input, the conversion
result value of the pertinent channel is undefined and cannot be
guaranteed. In addition, it may affect the conversion result values of the
other channels.
(b) Noise on the analog input pin (ADCAnIm) should be removed by
connecting a resistor Re between the pertinent pin and the external analog
signal input source and a capacitor Ce between the pertinent pin and the
AV
SSn
pin.
(c) Crossing or close positioning of the analog and digital signal lines should
be avoided as much as possible. The A/D conversion characteristics can
be degraded due to noise induction or other possible causes.
(d) For both the input and output ports near the ADCAnIm pin, it is
recommended to avoid high current drive and to use toggle switching as
infrequently as possible.