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RX
-
8581
SA
/
JE
/
NB
Page - 2 MQ372-02
3. Terminal description
3.1. Terminal connections
RX - 8581 SA
SOP − 14 pin
# 1
#
7
# 14
#
8
No. Pin terminal No. Pin terminal
1 N.C. 14 FOUT
2 SCL 13 N.C.
3 SDA 12 N.C.
4 N.C. 11 V
DD
5 GND 10 FOE
6 N.C. 9 N.C.
7
/
INT
8 N.C.
RX - 8581 JE
VSOJ − 20 pin
# 1
# 10
# 14
# 11
No. Pin terminal No. Pin terminal
1 N.C. 20 N.C.
2 N.C. 19 N.C.
3 FOE 18 N.C.
4V
DD
17 N.C.
5 FOUT 16 N.C.
6 SCL 15 N.C.
7 SDAT 14 N.C.
8
( V
DD
)
13 N.C.
9 GND 12 N.C.
10
/
INT
11 N.C.
RX - 8581 NB
SON − 22 pin
# 1
# 11
# 14
(#12)
No. Pin terminal No. Pin terminal
1 / INT 22 N.C.
2 GND 21 N.C.
3
(
V
DD
)
20 N.C.
4 N.C. 19 N.C.
5 SDA 18 N.C.
6 SCL 17 N.C.
7 FOUT 16 N.C.
8V
DD
15 N.C.
9 FOE 14 N.C.
10 N.C. (13)
−
11 N.C. (12)
−
3.2. Pin Functions
Signal
name
I/O Function
SCL I This is the serial clock input pin for I
2
C Bus communications.
SDA I/O
This pin's signal is used for input and output of address, data, and ACK bits,
synchronized with the serial clock used for I
2
C communications.
Since the SDA pin is an N-ch open drain pin during output, be sure to connect a suitable
pull-up resistance relative to the signal line capacity.
FOUT O
This is the C-MOS output pin with output control provided via the FOE pin.
When FOE = "H" (high level), this pin outputs a 32.768-kHz signal.
When output is stopped, the FOUT pin = "L" (low level).
FOE I
This is an input pin used to control the output mode of the FOUT pin.
When this pin's level is high, the FOUT pin is in output mode. When it is low, output via the
FOUT pin is stopped.
/INT O
This pins is used to output alarm signals, timer signals, time update signals, and other
signals. This pin is an open drain pin.
V
DD
−
This pin is connected to a positive power supply.
(V
DD
)
−
Although this pin has the same potential as V
DD,
it should not be connected externally.
GND
−
This pin is connected to a ground.
N.C.
−
This pin is not connected to the internal IC.
Leave N.C. pins open or connect them to GND or V
DD
.
(Note) Note with caution that in the RX-8581NB (SON-22 pin), the N.C. pins (pins 14 to
22) are interconnected via the internal frame.
Note: Be sure to connect a bypass capacitor rated at least 0.1 µF between V
DD
and GND.