New DTMF codec/FSK modem combo IC from CML

The CMX865 from CML Microcircuits is a multi-standard DTMF codec/FSK modem combo IC 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 ?C 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 are provided for use with asynchronous data and allow unformatted synchronous data to be received or transmitted as 8-bit words.

CML added that 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 new product also features a hook switch relay drive output and a ring detector circuit which continues to function when the device is in the power save mode, providing an interrupt which can be used to wake up the host ?Controller when line voltage reversal or ringing is detected.

The CMX865 operates from a single 3V to 3.6V supply over a temperature range of -40°C to 85°C and is available in a 24-pin SOIC package.