The CMX878 is a line-powered V.22 bis-based 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/DC mask, anti-reflective (AR) impedance control, and line voltage measurement. A complete line interface can be implemented with a small external component count, using low cost components.
Very low power consumption and built-in power management makes the CMX878 suitable for telephone
line power usage.
Furthermore, the microprocessor can be powered-down 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.
