CMX860 Telephone Signalling Transceiver

The CMX860 is a flexible, low-power telephone signalling transceiver IC, designed for use in a wide range of line-powered telephone equipment.
The IC combines the functions of a DTMF encoder and decoder, V.23 and Bell 202 modulator and demodulator plus call progression circuitry with analogue switching between line and phone interfaces.
Ring detection, local phone off-hook detection and a relay driver for line hook-switch operation are also provided under the control of 'C-BUS'.
The ring and hook detectors operate whilst the remainder of the IC is power-saving, generating an interrupt to wake-up the host μC when further processing or signalling is required.
All on-chip functions and switching arrangements are controlled via a serial bus ('C-BUS').
The CMX860 is designed to operate at 2.7V and utilises CML's low power DTMF decoder and V.23 modem technology.