CHAPTER 11 A/D CONVERTER
514
User’s Manual U15195EJ5V0UD
Figure 11-1. Block Diagram of A/D Converter 0 or 1
ADSCMn0 (16)
15
0
ADTRGn
INTADn
Sample and
hold circuit
ANIn0
ANIn1
ANIn2
ANIn3
ANIn4
ANIn5
ANI16
ANI17
ITRG0
16
16
16
16
ADSCMn1 (16)
15
0
ADETM0 (16)
15
0
ADETM1 (16)
15
0
9
0
Trigger source switching
circuit in timer trigger
mode (See
Figure 11-2
)
Controller
10
10
SAR (10)
Comparator
and D/A
converter
AV
DDn
AV
SSn
INTDETn
ADCRn0
ADCRn1
ADCRn2
ADCRn3
ADCRn4
ADCRn5
ADCR16
ADCR17
Internal bus
Input circuit
f
XX
/2
Remark
n = 0, 1
f
XX
: Internal system clock
Cautions 1. Noise at an analog input pin (ANI0m, ANI1n) or reference voltage input pin (AV
DD0
, AV
DD1
) may
give rise to an invalid conversion result (m = 0 to 5, n = 0 to 7).
Software processing is needed in order to prevent this invalid conversion result from
adversely affecting the system.
The following are examples of software processing.
• Use the average value of the results of multiple A/D conversions as the A/D conversion
result.
• Perform A/D conversion several times consecutively and use conversion results omitting
any abnormal conversion results that are obtained.
• If an A/D conversion result from which it is judged that an abnormality occurred in the
system is obtained, be sure to recheck the abnormality occurrence before performing
malfunction processing.
2. Be sure that voltages outside the range [AV
SS0
to AV
DD0
, AV
SS1
to AV
DD1
] are not applied to pins
being used as A/D converter 0 and 1 input pins.