cf8223a Nippon Precision Circuits Inc, (NPC), cf8223a Datasheet - Page 11

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

FSK Demodulator
When an FSK signal is received, the FSK/DTMF
signal discriminator circuit sets the FSK/DTMF pin
HIGH and connects the input signal to the FSK
demodulator circuit. Demodulated data is output on
DOUT with the format shown in figure 4. The FSK
signal conforms to the following Bellcore standard.
DTMF Demodulator
When a DTMF signal is received, the FSK/DTMF
signal discriminator circuit sets the FSK/DTMF pin
LOW and connects the input signal to the DTMF
demodulator circuit. The DTMF signal is comprised
by a high-group frequency and a low-group fre-
quency which, in combination, represent a point in
the DTMF matrix.
Table 2. DTMF matrix
The DTMF receiver demodulates the received
DTMF signal and outputs data bits Q
bit (2-mod-16) checksum S
DOUT.
Low group
697Hz
770Hz
852Hz
941Hz
1209Hz
1
4
7
*
FSK signal
DOUT
1336Hz
2
5
8
0
High group
0
to S
b4 b5 b6 b7
b
3
6
1477Hz
in serial format on
b
Figure 4. FSK signal to DOUT output
3
6
9
#
7
0
to Q
1
Start bit
0 b
3
1
1633Hz
and a 4-
A
B
C
D
0
0
LSB
b
1
CF8223A
b
0
b
2
b
1
b
Table 1. FSK signal
Table 3. DTMF signal output (DOUT)
3
Modulation type
Logic “1” data (mark)
Logic “0” data (space)
Signal level (mark)
Signal level (space)
Data transfer rate
b
Matrix
input
2
b
A
B
C
D
1
2
3
4
5
6
7
8
9
0
#
*
4
b
3
Parameter
b
5
b
4
D
Q
MSB Stop bit
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
b
0
0
6
b
5
b
7
Q
D
NIPPON PRECISION CIRCUITS INC.—11
b
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
6
1
1
DTMF
1
b
7
Continuous-phase binary frequency-shift-
keying
1200 ± 12 Hz
2200 ± 22 Hz
−32 to −12 dBm
−36 to −12 dBm
1200 ± 12 baud
D
Q
0 b
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
2
2
1
0
0
D
Q
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
b
3
3
1
b
0
Description
D
S
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
b
4
0
1
Checksum
D
S
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
5
D
S
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
6
2
D
S
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
7
3