upd17225 Renesas Electronics Corporation., upd17225 Datasheet - Page 35

• Manufacturer Part Number: upd17225
• Description: 4-bit Single-chip Microcontroller For Small General-purpose Infrared Remote Control Transmitter
• Manufacturer: Renesas Electronics Corporation.

Setting carrier frequency and duty factor
Where the system clock frequency is f
Example
is divided into m:n and is set in the modulo registers as follows:
NRZHTMM
High-level period set value = {
Low-level period set value = {
0FH
0FH
3FH
7FH
00H
01H
04H
09H
11H
11H
19H
(division ratio) = f
Where f
m:n = 1:2
From the above, the value of the modulo register is:
High-level period = 17
Low-level period = 34
Therefore, the carrier frequency is 37.74 kHz.
= 4 MHz/(2
Set value
C
= 38 kHz, duty factor (high-level period) = 1/3, and f
NRZLTMM
Table 5-1. Carrier Frequency List (f
00H
02H
04H
09H
10H
21H
21H
22H
35H
3FH
7FH
X
38 kHz) = 52.6
.
/(2
.
.
.
REM
(f
C
)
f
C
)
X
Data Sheet U12643EJ2V0DS00
and carrier frequency is f
t
H
13.0
32.0
64.0
0.5
1.0
2.5
5.0
8.0
8.0
9.0
9.0
m/(m + n)} – 1
n/(m + n)} – 1
( s)
t
H
1/f
C
t
L
t
L
17.0
17.0
17.5
27.0
32.0
64.0
0.5
1.5
2.5
5.0
8.0
( s)
PD17225, 17226, 17227, 17228
C
:
X
1/f
120.0
= 4 MHz)
10.0
16.5
25.0
26.0
26.5
40.0
64.0
C
1.0
2.5
5.0
( s)
X
= 4 MHz,
f
C
1000
60.6
40.0
38.5
37.7
25.0
15.6
400
200
100
7.8
(kHz)
Duty
1/2
2/5
1/2
1/2
1/2
1/3
1/3
1/3
1/3
1/2
1/2
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