CMX624P4 CMLMICRO [CML Microcircuits], CMX624P4 Datasheet - Page 9

• Manufacturer Part Number: CMX624P4
• Description: V.23 / Bell 202 Modem
• Manufacturer: CMLMICRO [CML Microcircuits]

V23 / Bell 202 Modem
Bell 202 mode (bit 7 of SETUP register = ‘1’):
When bit 7 of the TX TONES Register is set to ‘1’, the block generates DTMF tone pairs or single tones
from the DTMF range as shown in the table below. Bit 6 of the TX TONES Register is then used to enable
or disable the block’s output to the Tx filter.
1.5.7
This stage attenuates out of band signals present at the output of the FSK/DTMF modulator and also
includes a programmable 3dB level switch, selected by bit 2 of the FSK MODE Register.
The nominal output levels at the TOP pin when V
These levels are proportional to V
will depend on the external circuitry as described in Section 1.6.1.
recommended in Section 1.6.1 for a nominal FSK transmit level of -9dBm, DTMF tone levels of -8dBm and
-6dBm, then the out of band energy sent to the line will be within the limits shown in Figure 5 for both FSK
and DTMF signals.
 2003 CML Microsystems Plc
TX DATA Register Bits
FSK MODE Reg
D3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Bit 1
Transmit Filter
0
1
1
Register bit 2
1 (high level)
D2
0 (low level)
FSK MODE
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0 - 3
0dB = 775mVrms
Bit 0
0
1
x
D1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
D0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
FSK / DTMF Modulator block output
Disabled (o/p held at V
Frequency (Hz)
(Bit 7 of TX TONES = ‘0’)
DD
FSK Signal
, and the actual transmit signal levels present on the 2- or 4-wire line
Lower
941
697
697
697
770
770
770
852
852
852
941
941
941
697
770
852
-6dB
-3dB
1200bps FSK
150bps FSK
(TX TONES Register Bit 4 = ‘0’)
DTMF Tone Pairs
DD
Frequency (Hz)
= 5.0V are as shown below.
9
DD
Upper
1633
1209
1336
1477
1209
1336
1477
1209
1336
1477
1336
1209
1477
1633
1633
1633
/ 2)
DTMF Tone
(Low group)
-5dB
-2dB
‘0’ (Space)
Keypad
Legend
2200Hz
Using the external components
FSK Signal Frequency
487Hz
D
C
A
B
1
2
3
4
5
6
7
8
9
0
#
*
-
(High group)
DTMF Tone
Frequency (Hz)
-3dB
0dB
Single Tone
Single Tone
(Bit 4 = ‘1’)
‘1’ (Mark)
1633
1209
1336
1477
1209
1336
1477
1209
1200Hz
852
852
941
941
941
697
770
852
387Hz
-
CMX624
D/624/7