SM8224B
PIN DESCRIPTION
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Name
AG N D
TIP
RING
TRQ
GND
OSCIN
OSCOUT
MODE
TEST
DOUT
STR
DTDET
CR
CDET
VDD
S1
S0
DTQ
DT2
DT1
I/O
O
I
I
O
–
I
O
I
–
O
O
O
I/O
O
–
I
I
O
I
I
Function
Analog ground output. Internal reference voltage (V
D D
/2) output level
Tip input. Connected to the telephone line through a protection circuit
Ring input. Connected to the telephone line through a protection circuit
Input-stage amplifier gain-select output. Used to adjust the gain of the input-stage amplifier.
Ground. Connected to the system ground potential.
Cr ystal oscillator input. The crystal oscillator element is connected between this pin and OSCOUT.
Cr ystal oscillator output. The crystal oscillator element is connected between this pin and OSCIN.
When MODE is HIGH, and S1 and S0 are both LOW , the device is in pow er-down state. See table 2.
TEST pin. Set OPEN when nor mal using.
Data output. Demodulated FSK signal output. HIGH level output when C D E T goes HIGH.
Dual-tone confirmation output. Function is selected by S0 and S1. See table 2.
Dual-tone confirmation: Active-LOW output when dual tone detection signal passes through RC time
constant delay circuit.
Dual-tone detector output. HIGH-level output when dual tone is detected.
Dual tone RC time constant circuit connection. The dual tone detection signal passes through the RC
network to generate the S T R signal.
FSK signal carrier detector output. LOW -level when active carrier is detected.
Supply
Function select bit 1. Selects the device mode in combination with S0 and MODE. See table 2.
Function select bit 1. Selects the device mode in combination with S1 and MODE. See table 2.
Dual-tone signal input-stage amplifier output. Used to adjust the gain of the input-stage amplifier.
Dual-tone signal input-stage operational amplifier inverting input
Dual-tone signal input-stage operational amplifier non-inverting input
NIPPON PRECISION CIRCUITS—4
NPC [ NIPPON PRECISION CIRCUITS INC ]
