A-D CONVERTER
12.1 Overview
12.1 Overview
The A-D conversion is performed in the 8-bit resolution mode or the 10-bit resolution mode. Also, the input
voltage can be compared with the set value by using the A-D converter (in other words, the comparator
function). Whether to perform the A-D conversion or comparison can be selected for each pin.
❈ In chapter 12, the operations common to the A-D converter’s functions (8-bit resolution, 10-bit resolution,
comparator) are simply referred to as “operation.”
Table 12.1.1 lists the performance specifications of the A-D converter.
Table 12.1.1 Performance specifications of A-D converter
Item
A-D conversion method
Resolution
Performance specifications
Successive approximation conversion method
Either of 8-bit or 10-bit resolution can be selected by software.
8-bit resolution mode : ±2 LSB
Absolute accuracy
10-bit resolution mode : ±3 LSB
5 pins (AN0 to AN4)
Analog input pin (Note)
Conversion rate per analog input pin
8-bit resolution mode
: 49 φAD cycles
10-bit resolution mode : 59 φAD cycles
Comparator function Comparison operation Comparison between the set value and analog input voltage
Comparison rate per 14 φAD cycles
analog input pin
φAD : A-D converter’s operation clock
Note: For each of analog input pin AN (i = 0 to 4), whether to use pin AN as an input pin of the A-D converter or as that
i
i
of the comparator can be selected by using the comparator function select register 0 (address DC16).
(1) 8-bit resolution mode
The input voltage from pin AN (i = 0 to 4) is A-D converted, and the 8-bit A-D conversion result is
i
stored in A-D register i. (Refer to sections “12.3 A-D conversion method” and “12.5 Comparison
voltage in 8-bit resolution mode.”)
(2) 10-bit resolution mode
The input voltage from pin AN is A-D converted, and the 10-bit A-D conversion result is stored in
i
A-D register i. (Refer to section “12.3 A-D conversion method.”)
(3) Comparator function
The 8-bit value which has been set in A-D register i is compared with the voltage input from pin AN ;
i
and then, the result of comparison is stored into the AN pin comparator result bit. (Refer to section
i
“12.6 Comparator function.”)
7906 Group User’s Manual Rev.2.0
12-2
RENESAS [ RENESAS TECHNOLOGY CORP ]
