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S3C9454B/F9454B
INTERNAL REFERENCE VOLTAGE LEVELS
In the ADC function block, the analog input voltage level is compared to the reference voltage. The analog input
level must remain within the range V
Different reference voltage levels are generated internally along the resistor tree during the analog conversion
process for each conversion step. The reference voltage level for the first bit conversion is always 1/2 V
ADC0/P0.0
ADC1/P0.1
ADC2/P0.2
ADC7/P0.7
ADC8/P2.6
ADDATAH
ADDATAL
to V
SS
DD.
ADCON.7-.4
Control
Circuit
M
U
L
T
I
P
L
E
X
E
R
Figure 12-2. A/D Converter Circuit Diagram
MSB
.7
MSB
-
Figure 12-3. A/D Converter Data Register (ADDATAH/L)
A/D Converter Control Register
ADCON (F7H)
ADCON.0 (ADEN)
ADCON.2-.1
+
-
Analog
Comparator
V
DD
D/A Converter
V
SS
.6
.5
.4
.3
-
-
-
-
Clock
ADCON.3
Selector
(EOC Flag)
Successive
Approximation
Circuit
Conversion Result
ADDATAH
ADDATAL
(F8H)
(F9H)
To data bus
.2
.1
.0
LSB
-
.1
.0
LSB
A/D CONVERTER
DD.
12-3
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