EM78P458/459
OTP ROM
Fig. 11 Interrupt Input Circuit
4.7 Analog-To-Digital Converter (ADC)
The analog-to-digital circuitry consists of an 8-bit analog multiplexer, three control registers
(ADCON/R9, AD-CMP-CON/IOCA0, GCON/IOC90), one data register (ADDATA/RA) and an ADC
with 8-bit resolution. The functional block diagram of the ADC is shown in Fig. 12. The analog
reference voltage (Vref) and analog ground are connected via separate input pins.
The ADC module utilizes successive approximation to convert the unknown analog signal into a
digital value. The result is fed to the ADDATA. Input channels are selected by the analog input
multiplexer via the ADCON register Bits ADIS0, ADIS1, and ADIS2.
ADC8
ADC7
ADC6
ADC5
Vref
+
-
Power-Down
OP2
ADC
Start to Convert
( successive approximation )
ADC4
ADC3
ADC2
ADC1
Fsco
4-1
MUX
+
-
OP1
3
Internal
RC
4
3
2
5
4
2
1
0
2
1
0
1
0
3
7
6
5
4
3
2
1
0
4
3
AD-CMPCON
ADCON AD-CMPCON
RF
ADDATA
ADCON
GCON
DATA BUS
Fig. 12 The Functional Block Diagram of Analog-to-Digital Conversion
This specification is subject to change without prior notice.
31
06.25.2004 (V1.4)
ELAN [ ELAN MICROELECTRONICS CORP ]
