CMX624P4 CMLMICRO [CML Microcircuits], CMX624P4 Datasheet - Page 6

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

V23 / Bell 202 Modem
1.4
1.5
The CMX624 contains a V.23/Bell 202 compatible FSK modem capable of duplex operation at 1200/75 or
1200/150 bps over a 2-wire line or 1200/1200 bps over a 4-wire line, a flexible FSK data UART, a receive
FSK or Call Progress Tone energy detector, a 2100Hz detector, a DTMF generator, a Tx line driving buffer
amplifier, a telephone line Ringing Signal or Line Voltage Reversal detector and a 3.579545MHz Xtal
oscillator. These functions are all controlled over a ‘C-BUS’ serial C interface which also carries the
transmit and receive FSK modem data.
1.5.1
Frequency and timing accuracy of the CMX624 is determined by a 3.579545MHz clock present at the
XTAL/CLOCK pin. This may be generated by the on-chip oscillator inverter using the external components
C1, C2 and X1 of Figure 2, or may be supplied from an external source to the XTAL/CLOCK input. If the
clock is supplied from an external source, C1, C2 and X1 should not be fitted.
The on-chip oscillator is turned off in the 'Zero-Power' mode.
If the clock is provided by an external source which is not always running, then the 'Zero-Power' mode
must be set when the clock is not available. Failure to observe this rule may cause a rise in the supply
current drawn by CMX624.
 2003 CML Microsystems Plc
External Components
General Description
Xtal Osc and Clock Dividers
Figure 2 Recommended External Components for Typical Application
Resistors 5%, capacitors 10% unless otherwise stated.
* This component is only required for compatibility with CMX644A,
R1
X1
see CMX644A Data Sheet for further details.
100k
3.579545MHz
6
C1, C2
C5
C3, C4
18pF
0.1 F
*
CMX624
D/624/7