32. 12-Bit A/D Converter (S12AD)
Under development Preliminary document
Specifications in this document are tentative and subject to change.
32.
12-Bit A/D Converter (S12AD)
32.1
Overview
The RX210 Group includes a 12-bit successive approximation A/D converter. Up to 16 channel analog inputs,
temperature sensor outputs, or internal reference voltages can be selected.
The 12-bit A/D converter converts a maximum of 16 selected channels of analog inputs, temperature sensor outputs, or
internal reference voltages into a 12-bit digital value through successive approximation.
The A/D converter has three operating modes: single-cycle scan mode in which the analog inputs of up to 16 arbitrarily
selected channels are converted for only once in ascending channel order; and continuous scan mode in which the analog
inputs of up to 16 arbitrarily selected channels are continuously converted in ascending channel order; and group scan
mode in which up to 16 channels of the analog inputs are arbitrarily divided into two groups (group A and group B) and
converted in ascending channel order in each group.
In group scan mode, the scan start conditions of group A and group B can be independently selected, thus allowing A/D
conversion of group A and group B to be started independently.
In double trigger mode, one arbitrarily selected analog input channel is converted in single-cycle scan mode or group
scan mode (group A), and the resulting data of A/D conversion started by the first and second triggers are stored into
separate registers (duplication of A/D conversion data).
Self-diagnosis is executed once at the beginning of each scan, and one of the three voltages internally generated in the
12-bit A/D converter is converted.
A/D conversion of the temperature sensor output or the internal reference voltage is accomplished independently.
Table 32.1 lists the specifications of the 12-bit A/D converter and
Table 32.2 indicates the functions of the 12-bit A/D
converter.
Figure 32.1 shows a block diagram of the 12-bit A/D converter.
Table 32.1
Specifications of 12-Bit A/D Converter (1 / 2)
Item
Specifications
Number of units
One unit
Input channels
Up to 16 channels
Extended analog inputs
Temperature sensor output, internal reference voltage
A/D conversion method
Successive approximation method
Resolution
12 bits
Conversion time
1.0 μs per channel (when A/D conversion clock ADCLK = 50 MHz)
A/D conversion clock
Peripheral module clock PCLK*1 and A/D conversion clock ADCLK*1 can be set so that the frequency division ratio should be one of the following.
PCLK to ADCLK frequency division ratio = 1:1, 1:2, 1:4, 1:8, 2:1, 4:1
ADCLK is set using the clock generation circuits.
Data registers
For analog input: 16 data registers
For duplication of A/D conversion data in double trigger mode: One data register
For temperature sensor: One data register
For internal reference voltage: One data register
The A/D conversion result is stored in 12-bit A/D data registers.
In addition mode, A/D conversion results are added and stored in A/D data registers as 14-bit data.
Duplication of A/D conversion data
A/D conversion data of one selected analog input channel is stored into A/D data register y when
conversion is started by the first trigger and into the duplication register when started by the second
trigger.
Duplication is available only in double trigger mode in single-cycle scan mode or group scan mode.