CMX878
Line Powered
Modem plus DAA
D/878/1 February 2002
Advance Information
Features
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V.22bis, V.22, Bell 212A, V.23/Bell 202,
V.21/Bell 103 modulation schemes
DTMF/Tones Transmit and Receive
Line Reversal and Ring Detection
Regulated Power taken from Line
Gyrator and Impedance Matching Control
Parallel Phone Detection
Low Power Operation and Standby
Applications
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Line Powered Applications
EPOS Terminals
Remote Utility Meter Reading
Security Systems
Telephone Telemetry Systems
ATMs
Pay-Phones
E-mail Terminals
EXTRACTED
POWER
APPLICATION
CIRCUITRY
TIP
RING
LINE
INTERFACING
CMX878
VDD
CBUS
MICROPROCESSOR
1.1
Brief Description
The CMX878 is a line-powered multi-standard modem for use in telephone based information and
telemetry systems. It provides the building blocks for interfacing to the telephone line without the need
for a transformer - this is the Data Access Arrangement (DAA) – allowing for the coupling of data signals
to and from the line; it can also detect Ringing and Line Reversals.
Provision is made for the conditioning and monitoring of other aspects of the telephone line – this
includes the gyrator/loop current, line impedance control, and line voltage measurement. A complete line
interface can be implemented using low cost external components.
Very low power consumption and built-in power management makes the CMX878 suitable for telephone
line power usage. Furthermore the microcontroller can be de-powered whilst awaiting the detection of a
Ring, Line Reversal, or WAKE pin event.
Control of the device is via a simple high speed serial bus, compatible with most types of µC serial
interface. Data transmitted and received by the modem is transferred over the same serial bus.
The CMX878 is available in 28-pin SOIC, SSOP and TSSOP packages.
©
2002 Consumer Microcircuits Limited
CMLMICRO [ CML MICROCIRCUITS ]
