M16C62P_06 Datasheet, PDF (263/421 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

M16C/62P Group (M16C/62P, M16C/62PT)
18. A/D Converter
18.2 Function
18.2.1 Resolution Select Function
The desired resolution can be selected using the BITS bit in the ADCON1 register. If the BITS bit is set to “1”
(10-bit conversion accuracy), the A/D conversion result is stored in the bit 0 to bit 9 in the ADi register (i = 0 to
7). If the BITS bit is set to “0” (8-bit conversion accuracy), the A/D conversion result is stored in the bit 0 to bit
7 in the ADi register.
18.2.2 Sample and Hold
If the SMP bit in the ADCON2 register is set to “1” (with sample-and-hold), the conversion speed per pin is
increased to 28 φAD cycles for 8-bit resolution or 33 φAD cycles for 10-bit resolution. Sample and Hold is
effective in all operating modes. Select whether or not to use the Sample and Hold function before starting A/D
conversion.
18.2.3 Extended Analog Input Pins
In one-shot and repeat modes, the ANEX0 and ANEX1 pins can be used as analog input pins. Use the OPA1 to
OPA0 bits in the ADCON1 register to select whether or not use ANEX0 and ANEX1.
The A/D conversion results of ANEX0 and ANEX1 inputs are stored in the AD0 and AD1 registers,
respectively.
18.2.4 18.2.4 External Operation Amplifier (Op-Amp) Connection Mode
Multiple analog inputs can be amplified using a single external op-amp via the ANEX0 and ANEX1 pins. Set
the OPA1 to OPA0 bits in the ADCON1 register to “11b” (external op-amp connection mode). The inputs from
ANi (i = 0 to 7) (1) are output from the ANEX0 pin. Amplify this output with an external op-amp before sending
it back to the ANEX1 pin. The A/D conversion result is stored in the corresponding ADi register. The A/D
conversion speed depends on the response characteristics of the external op-amp. Figure 18.10 shows an
example of How to Connect the Pins in External Op-Amp.
1. AN0_i and AN2_i can be used the same as ANi. However, if VCC2 < VCC1, do not use AN0_i and
AN2_i as analog input pins.
ADGSEL1 to ADGSEL0 bits in ADCON2 register = 00b
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
AN0_0
AN0_1
AN0_2
AN0_3
AN0_4
AN0_5
AN0_6
AN0_7
AN2_0
AN2_1
AN2_2
AN2_3
AN2_4
AN2_5
AN2_6
AN2_7
ANEX0
ADGSEL1 to ADGSEL0 bits = 10b
ADGSEL1 to ADGSEL0 bits = 11b
ANEX1
External Op-Amp
Microcomputer
Resistor ladder
Successive conversion
register
Comparator
Figure 18.10 External Op-Amp Connection
Rev.2.41 Jan 10, 2006 Page 248 of 390
REJ09B0185-0241