Datasheet
CHAPTER 9 A/D CONVERTER (
μ
PD78F920x ONLY)
User’s Manual U18172EJ3V0UD
158
Table 9-1. Sampling Time and A/D Conversion Time
fXP = 8 MHz fXP = 10 MHz Reference
Voltage
Range
Note 1
Sampling
Time
Note 2
Conversion
Time
Note 3
Sampling
Time
Note 2
Conversion
Time
Note 3
Sampling
Time
Note 2
Conversion
Time
Note 3
FR2 FR1 FR0
VDD ≥ 4.5 V 12/fXP 36/fXP 1.5
μ
s 4.5
μ
s 1.2
μ
s 3.6
μ
s 0 0 0
VDD ≥ 4.0 V 24/fXP 72/fXP 3.0
μ
s 9.0
μ
s 2.4
μ
s 7.2
μ
s 1 0 0
96/fXP 144/fXP 12.0
μ
s 18.0
μ
s 9.6
μ
s 14.4
μ
s 1 1 0
48/fXP 96/fXP 6.0
μ
s 12.0
μ
s 4.8
μ
s 9.6
μ
s 1 0 1
48/fXP 72/fXP 6.0
μ
s 9.0
μ
s 4.8
μ
s 7.2
μ
s 0 1 0
VDD ≥ 2.85 V
24/f
XP 48/fXP 3.0
μ
s 6.0
μ
s Setting
prohibited
Note 4
(2.4
μ
s)
Setting
prohibited
Note 4
(4.8
μ
s)
0 0 1
176/fXP 224/fXP 22.0
μ
s 28.0
μ
s 17.6
μ
s 22.4
μ
s 1 1 1 VDD ≥ 2.7 V
88/f
XP 112/fXP 11.0
μ
s 14.0
μ
s Setting
prohibited
Note 4
(8.8
μ
s)
Setting
prohibited
Note 4
(11.2
μ
s)
0 1 1
Notes 1. Be sure to set the FR2, FR1, and FR0, in accordance with the reference voltage so that Notes 2 and 3
below are satisfied.
Example When V
DD ≥ 2.7 V, fXP = 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.
2. Set the sampling time as follows.
• V
DD ≥ 4.5 V: 1.0
μ
s or more
• V
DD ≥ 4.0 V: 2.4
μ
s or more
• VDD ≥ 2.85 V: 3.0
μ
s or more
• V
DD ≥ 2.7 V: 11.0
μ
s or more
3. Set the A/D conversion time as follows.
• V
DD ≥ 4.5 V: 3.0
μ
s or more and less than 100
μ
s
• V
DD ≥ 4.0 V: 4.8
μ
s or more and less than 100
μ
s
• V
DD ≥ 2.85 V: 6.0
μ
s or more and less than 100
μ
s
• VDD ≥ 2.7 V: 14.0
μ
s or more and less than 100
μ
s
4. Setting is prohibited because the values do not satisfy the condition of Notes 2 or 3.
Caution The above sampling time and conversion time do not include the clock frequency error. Select
the sampling time and conversion time such that Notes 2 and 3 above are satisfied, while taking
the clock frequency error into consideration (an error margin maximum of ±5% when using the
high-speed internal oscillator).
Remarks 1. f
XP: Oscillation frequency of clock to peripheral hardware
2. The conversion time refers to the total of the sampling time and the time from successively
comparing with the sampling value until the conversion result is output.