Datasheet
CHAPTER 12 10-BIT SUCCESSIVE APPROXIMATION TYPE A/D CONVERTER (
μ
PD78F041x only)
User’s Manual U18698EJ1V0UD
296
Table 12-2. A/D Conversion Time Selection
(1) 2.7 V ≤ AVREF ≤ 5.5 V
A/D Converter Mode Register (ADM) Conversion Time Selection
FR3 FR2 FR1 FR0 LV1 LV0 fPRS =
2 MHz
fPRS =
8 MHz
fPRS =
10 MHz
Conversion Clock (fAD)
1
× × ×
0 0 352/fPRS 44.0
μ
s 35.2
μ
s fPRS/16
0 0 0 0 0 0 264/fPRS 33.0
μ
s 26.4
μ
s fPRS/12
0 0 0 1 0 0 176/fPRS 22.0
μ
s 17.6
μ
s fPRS/8
0 0 1 0 0 0 132/fPRS
Setting
prohibited
16.5
μ
s 13.2
μ
s fPRS/6
0 0 1 1 0 0 88/fPRS 44.0
μ
s 11.0
μ
s
Note
8.8
μ
s
Note
fPRS/4
0 1 0 0 0 0 66/fPRS 33.0
μ
s 8.3
μ
s
Note
6.6
μ
s
Note
fPRS/3
0 1 0 1 0 0 44/fPRS 22.0
μ
s
Setting
prohibited
Setting
prohibited
f
PRS/2
Other than above Setting prohibited
Note This can be set only when 4.0 V ≤ AVREF ≤ 5.5 V.
(2) 2.3 V ≤ AV
REF < 2.7 V
A/D Converter Mode Register (ADM) Conversion Time Selection
FR3 FR2 FR1 FR0 LV1 LV0 fPRS =
2 MHz
fPRS =
5 MHz
fPRS =
8 MHz
Conversion Clock (fAD)
0 0 0 0 0 1 480/fPRS Setting
prohibited
60.0
μ
s fPRS/12
0 0 0 1 0 1 320/fPRS 64.0
μ
s 40.0
μ
s fPRS/8
0 0 1 0 0 1 240/fPRS 48.0
μ
s 30.0
μ
s fPRS/6
0 0 1 1 0 1 160/fPRS
Setting
prohibited
32.0
μ
s fPRS/4
0 1 0 0 0 1 120/fPRS 60.0
μ
s fPRS/3
0 1 0 1 0 1 80/fPRS 40.0
μ
s
Setting
prohibited
Setting
prohibited
f
PRS/2
Other than above Setting prohibited
Cautions 1. Set the conversion times with the following conditions.
• 4.0 V ≤ AV
REF ≤ 5.5 V: Sampling + successive conversion time = 5 to 40
μ
s
(fAD = 0.6 to 3.6 MHz)
• 2.7 V ≤ AV
REF < 4.0 V: Sampling + successive conversion time = 10 to 40
μ
s
(f
AD = 0.6 to 1.8 MHz)
• 2.3 V ≤ AV
REF < 2.7 V: Sampling + successive conversion time = 25 to 75
μ
s
(f
AD = 0.6 to 1.48 MHz)
2. When rewriting FR3 to FR0, LV1, and LV0 to other than the same data, stop A/D conversion
once (ADCS = 0) beforehand.
3. Change LV1 and LV0 from the default value, when 2.3 V ≤ AV
REF < 2.7 V.
4. The above conversion time does not include clock frequency errors. Select conversion time,
taking clock frequency errors into consideration.
Remark f
PRS: Peripheral hardware clock frequency