Renesas M16C Series User Manual

A-D Converter
M30240 Group
Rev.1.00 Sep 24, 2003 Page 99 of 360
1.2.24 A-D Converter
The A-D converter consists of one 10-bit successive approximation A-D converter circuit with a
capacitive coupling amplifier. Pins P10
0
to P10
7
function as the analog signal input pins. The direction
registers of these pins for A-D conversion must therefore be set to input. The Vref connect bit (bit 5 at
address 03D7
16
) can be used to isolate the resistance ladder of the A-D converter from the reference
voltage input pin (V
REF
) when the A-D converter is not used. Doing so stops any current flowing into the
resistance ladder from V
REF
, reducing the power dissipation. When using the A-D converter, start A-D
conversion only after setting bit 5 of 03D7
16
to connect V
REF
.
The result of A-D conversion is stored in the A-D registers of the selected pins. When set to 10-bit
precision, the low 8 bits are stored in the even addresses and the high 2 bits in the odd addresses. When
set to 8-bit precision, the low 8 bits are stored in the even addresses.
Table 1.30 shows the performance of the A-D converter. Figure 1.96 shows the block diagram of the A-
D converter, and Figure 1.97 and Figure 1.98 show the A-D converter-related registers.
Table 1.30: Performance of A-D Converter
a
a.
Item Performance
Method of A-D conversion Successive approximation (capacitive coupling amplifier)
Analog input voltage (Note) 0V to AV
CC
(V
CC
)
Operating clock fAD V
CC
= 5V f
AD
/divide-by-2 or f
AD
/divide-by-4 or f
AD
, f
AD
,f(X
IN
)
Resolution 8-bit or 10-bit (selectable)
Absolute precision
V
CC
= 5V
• Without sample and hold function
±3LSB
• With sample and hold function (8-bit resolution)
±2LSB
• With sample and hold function (10-bit resolution)
3LSB
Operating modes
One-shot mode, repeat mode, single sweep mode, repeat sweep mode 0, and
repeat sweep mode 1
Analog input pins 8pins (AN
0
to AN
7
)
A-D conversion start condition
•Software trigger
A-D conversion starts when the A-D conversion start flag changes to “1”
•External trigger (can be re-triggered)
A-D conversion starts when the A-D conversion start flag is “1” and the AD
TRG
/P87
input changes from “H” to “L”
Conversion speed per pin
•Without sample and hold function
8-bit resolution: 49
φAD cycles, 10-bit resolution: 59 φAD cycles
• With sample and hold function
8-bit resolution: 28 φAD cycles, 10-bit resolution: 33 φAD cycles
Note: Does not depend on use of sample and hold function

Renesas M16C Series Specifications

General

Brand	Renesas
Model	M16C Series
Category	Computer Hardware
Language	English