cf8223a Nippon Precision Circuits Inc, (NPC), cf8223a Datasheet - Page 9

• Manufacturer Part Number: cf8223a
• Description: Fsk Decoder And Dtmf Receiver Ic
• Manufacturer: Nippon Precision Circuits Inc, (NPC)

The voltage divider level and RC time constant are
given by the following equations, respectively.
where t is the guard time, and the trigger level satis-
fies the expression 0.3V
C
0.7V
1
R
4
DD
=
-------------------------------------
In
=



------------------------- -
V
-------------------------------- V
R
DD
1
V
+
t
DD
–
R
R
1
2
V
DD
+
T
V
V
V
V
Figure 2. Ring signal detector circuit waveform transitions



R
V
V
V
V
≤ V
DD
DD
DD
DD
3
SS
SS
SS
SS
⋅
T
RIG
≤ 0.7V
DD
.
Point a Signal
Point b Signal
Point c Signal
Point d Signal
CF8223A
NIPPON PRECISION CIRCUITS INC.—9
V
0.7V
0.3V
V
0.7V
0.3V
0.7V
0.3V
0.7V
0.3V
RIG
RIG
DD
DD
DD
DD
DD
DD
DD
DD