Table of Contents
Advertisement
M30245 Group
2.9 A/D Converter
2.9.1 Overview
The A/D converter used in the M30245 group operates on a successive conversion basis. The following
is an overview of the A/D converter.
(1) Mode
The A/D converter operates in one of five modes:
(a) One-shot mode
Carries out A/D conversion on input level of one specified pin only once.
(b) Repetition mode
Repeatedly carries out A/D conversion on input level of one specified pin.
(c) One-shot sweep mode
Carries out A/D conversion on input level of two or more specified pins only once.
(d) Repeated sweep mode 0
Repeatedly carries out A/D conversion on input level of two or more specified pins.
(e) Repeated sweep mode 1
Repeatedly carries out A/D conversion on input level of two or more specified pins. This mode is
different from the repeated sweep mode 0 in that weights can be assigned to specifing pins control
the number of conversion times.
(2) Operation clock
The operation clock can be selected from the following: f
divide-by-4 f
AD
tion clock to 10 MHz or lower. When f(X
by dividing.
(3) Conversion time
Number of conversion for A/D convertor varies depending on resolution as given. Table 2.9.1 shows
relation between the A/D converter operation clock and conversion time.
Sample & Hold function selected:
33 φAD cycles for 10-bit resolution, or 28 φAD cycles for 8-bit resolution
No Sample & Hold function:
59 φAD cycles for 10-bit resolution, or 49 φAD cycles for 8-bit resolution
Table 2.9.1. Conversion time every operation clock
Frequency select bit 1
Frequency select bit 0
A/D converter's
operation clock
Min. conversion
cycles (Note 1)
Min. conversion
time (Note 2)
Note 1: The number of conversion cycles per one analog input pin.
Note 2: The conversion time per one analog input pin (when f
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
. The f
frequency is equal to that of the CPU's main clock (f
AD
8-bit mode
10-bit mode
8-bit mode
10-bit mode
page 213 of 354
, divide-by-2 f
AD
) is over 10 MHz, the f
IN
1
0
φ
φ
= f
/3
AD
AD
AD
8.4µs
11.2µs
9.9µs
13.2µs
= f(X
) = 10 MHz)
AD
IN
2. A/D Converter
, divide-by-3 f
AD
=f(X
)). Set the opera-
AD
IN
frequency must be under 10 MHz
AD
0
0
0
1
φ
= f
/4
= f
/2
AD
AD
AD
φAD
28
φAD
33
5.6µs
6.6µs
, and
AD
1
1
φ
= f
AD
AD
2.8µs
3.3µs
Advertisement
Table of Contents
