CHAPTER 10 A/D CONVERTER
User’s Manual U17446EJ3V1UD
166
Notes 2.
Be sure to set the FR2, FR1, and FR0, in accordance with the reference voltage so that
Notes 3
and
4
below are satisfied.
Example
When
AV
REF
≥
2.7 V, f
XP
= 8 MHz
•
The sampling time is 11.0
μ
s or more and the A/D conversion time is 14.0
μ
s or
more and 100
μ
s or less.
•
Set FR2, FR1, and FR0 = 0, 1, 1 or 1, 1, 1.
3.
Set the sampling time as follows.
•
AV
REF
≥
4.5 V:
1.0
μ
s or more
•
AV
REF
≥
4.0 V:
2.4
μ
s or more
•
AV
REF
≥
2.85 V: 3.0
μ
s or more
•
AV
REF
≥
2.7 V: 11.0
μ
s or more
4.
Set the A/D conversion time as follows.
•
AV
REF
≥
4.5 V:
3.0
μ
s or more and less than 100
μ
s
•
AV
REF
≥
4.0 V:
4.8
μ
s or more and less than 100
μ
s
•
AV
REF
≥
2.85 V: 6.0
μ
s or more and less than 100
μ
s
•
AV
REF
≥
2.7 V:
14.0
μ
s or more and less than 100
μ
s
5.
The operation of the comparator is controlled by ADCS and ADCE, and it takes 1
μ
s from
operation start to operation stabilization. Therefore, when ADCS is set to 1 after 1
μ
s or more
has elapsed from the time ADCE is set to 1, the conversion result at that time has priority over
the first conversion result. If the ADCS is set to 1 without waiting for 1
μ
s or longer, ignore the
first conversion data.
Table 10-2. Settings of ADCS and ADCE
ADCS ADCE
A/D
Conversion Operation
0
0
Stop status (DC power consumption path does not exist)
0
1
Conversion waiting mode (only comparator consumes power)
1
×
Conversion mode
Figure 10-4. Timing Chart When Comparator Is Used
ADCE
Comparator
ADCS
Conversion
operation
Conversion
operation
Conversion stopped
Conversion
waiting
Comparator operating
Note
Note
The time from the rising of the ADCE bit to the rising of the ADCS bit must be 1
μ
s or
longer to stabilize the internal circuit.
Caution 1. The above sampling time and conversion time do not include the clock frequency error.
Select the conversion time taking the clock frequency error into consideration (an error
margin maximum of
±
5% when using the high-speed internal oscillator).
Содержание 78K0S/KB1+
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