Specifications

RMU800A SERVICE MANUAL
－ 85 －
7. DTMF Receiver: LC73872M (TX-RX Unit IC122)
7-1 Pin Function
Pin No. Name I/O Description
1 INPUT I Signal input.
2 NC No connection.
3 PD I The IC goes to lower power mode when this pin is pulled high.
4 OSCO O Oscillator output.
5 OSCI I Oscillator input.
6 NC No connection.
7 V
SS
GND.
8 LOAD I
Inputting a clock to this pin allows the serial data to be output two
or more times.
9 SD O The decoded DTMF signal is output.
10 ACK I Shifting out data from SD pin.
11 STD O A high level indicates the presence of a DTMF signal.
12 EST O A high level indicates the presence of a DTMF signal.
13 NC No connection.
14 V
DD
+5V.
8. D/A converter with buffer amplifier: M62364FP (TX-RX Unit IC125)
8-1 Pin Function
Pin No. Name I/O Description
1,4,9,12,13,16,21,24
V
IN1
～V
IN8
I D/A converter input.
2,3,10,11,14,15,22,23
V
OUT1
～V
OUT8
O D/A converter output with 8-bit resolution.
5 V
DD
+5V.
6 LD I A low state enables data loading to shift register.
7 CLK I Shift clock input.
8 DI I Serial data input.
17 DO O Serial data output.
18 V
DAref
I D/A Converter reference voltage input.
19 RESET I Reset 8-bit latches.
20 GND GND.