CML Microcircuits
COMMUNICATION SEMICONDUCTORS
D/868A/3
CMX868A
Low Power
V.22 bis Modem
May 2008
Features
Applications
• V.22 bis 2400/2400 bps QAM
• Telephone Telemetry Systems
• V.22, Bell 212A 1200/1200 or 600/600 bps DPSK
• Remote Utility Meter Reading
• V.23 1200/75, 1200/1200, 75, 1200 bps FSK
• Security Systems
• Bell 202 1200/150, 1200/1200, 150, 1200 bps FSK
• Industrial Control Systems
• V.21 or Bell 103 300/300 bps FSK
• Electronic Cash Terminals
• DTMF/Tones Transmit and Receive
• Pay-Phones
• ‘Powersave’ Standby Mode
• Set-Top Boxes
1.
Brief Description
The CMX868A is a multi-standard modem for use in telephone based information and telemetry systems.
Control of the device is via a simple high speed serial bus, compatible with most types of µC serial
interface. The data transmitted and received by the modem is also transferred over the same serial bus.
On-chip programmable Tx and Rx USARTs meeting the requirements of V.14 are provided for use with
asynchronous data and allow unformatted synchronous data to be received or transmitted as 8-bit words.
A high-quality DTMF decoder with excellent immunity to falsing on voice and a standard DTMF encoder
are included. Alternatively, these blocks can be used to transmit and detect user-specific, programmed
single and dual-tone signals, call progress signals or modem calling and answering tones.
Flexible line driver and receive hybrid circuits are integrated on chip, requiring only passive external
components to build a 2 or 4-wire line interface.
The device also features a hook switch relay drive output and a Ring Detector circuit which continues to
function when the device is in the Powersave mode, providing an interrupt which can be used to wake up
the host µController when line voltage reversal or ringing is detected.
The CMX868A operates from a single 2.7 to 5.5V supply over a temperature range of -40°C to +85°C and
is available in 24-pin TSSOP, SOIC and DIP packages.
© 2008 CML Microsystems Plc
