Datasheet

RL78/L12 CHAPTER 11 A/D CONVERTER
R01UH0330EJ0200 Rev.2.00 334
Dec 13, 2013
CHAPTER 11 A/D CONVERTER
The number of analog input channels of the A/D converter differs, depending on the product.
32-pin 44-pin 48-pin 52, 64-pin
Analog
input
channels
4 ch
(ANI0, ANI1,
ANI18, ANI19)
7 ch
(ANI0, ANI1,
ANI17 to ANI21)
9 ch
(ANI0, ANI1,
ANI16 to ANI22)
10 ch
(ANI0, ANI1,
ANI16 to ANI23)
Caution Most of the following descriptions in this chapter use the 64-pin as an example.
11.1 Function of A/D Converter
The A/D converter is used to convert analog input signals into digital values, and is configured to control analog inputs,
including up to 10 channels of A/D converter analog inputs (ANI0, ANI1 and ANI16 to ANI23). 10-bit or 8-bit resolution can
be selected by the ADTYP bit of the A/D converter mode register 2 (ADM2).
The A/D converter has the following function.
• 10-bit resolution A/D conversion
Note
10-bit resolution A/D conversion is carried out repeatedly for one analog input channel selected from ANI0, ANI1 and
ANI16 to ANI23. Each time an A/D conversion operation ends, an interrupt request (INTAD) is generated.
Various A/D conversion modes can be specified by using the mode combinations below.
Trigger mode Software trigger Conversion is started by software.
Hardware trigger no-wait mode Conversion is started by detecting a hardware trigger.
Hardware trigger wait mode
The power is turned on by detecting a hardware trigger while the system
is off and in the conversion standby state, and conversion is then started
automatically after the stabilization wait time passes.
When using the SNOOZE mode function, specify the hardware trigger
wait mode.
Conversion operation
mode
One-shot conversion mode A/D conversion is performed on the selected channel once.
Sequential conversion mode
A/D conversion is sequentially performed on the selected channels until
it is stopped by software.
Operation voltage mode Standard 1 or standard 2 mode Conversion is done in the operation voltage range of 2.7 V ≤ VDD ≤ 5.5 V.
Low voltage 1 or low voltage 2
mode
Conversion is done in the operation voltage range of 1.6 V ≤ V
DD ≤ 5.5 V.
Select this mode for conversion at a low voltage. Because the operation
voltage is low, it is internally boosted during conversion.
Sampling time selection
Sampling clock cycles:
7 f
AD
The sampling time in standard 1 or low voltage 1 mode is seven cycles
of the conversion clock (fAD). Select this mode when the output
impedance of the analog input source is high and the sampling time
should be long.
Sampling clock cycles:
5 f
AD
The sampling time in standard 2 or low voltage 2 mode is five cycles of
the conversion clock (fAD). Select this mode when enough sampling time
is ensured (for example, when the output impedance of the analog input
source is low).
<R>
<R>
<R>