CML Microcircuits
COMMUNICATION SEMICONDUCTORS
UM8661/4 June 2004
DE8661
V.22bis User Manual
for a "socket modem"
Provisional Issue
1.0
Features
•
FCC68 or CTR21 DAA
•
Single 3V or 5V dc power supply
operation
•
Break-off PCB sections support
'desktop' and 'socket' modem use
•
PCB layout data provided
•
CMX866-based socket modem Reference Design
•
Fully Isolated 2-Wire Line Interface
•
Opto Isolated Ring Detect Circuitry and
OptoMOS Hook Relay
•
Integral AT Command Set with 'Fast Connect'
•
PC Controlled via Terminal Emulator
1.1
Brief Description
The DE8661 Demonstration Board is a reference design for the CMX866 V.22 bis AT command modem
IC. The main "socket modem" section contains the CMX866 and associated components in addition to
the line interface components. Attached to the main section are two break-off sections which contain a 9-
pin D type socket for PC serial communications, RJ11 line connector, supply voltage connector and a
hook-state LED. The CMX866 contains an on-chip
µController,
which interprets AT Commands issued via
a standard terminal emulator program running on a host PC or via an external
µController.
Interfacing to the Demonstration Board can be via socket pins on the socket modem section, or via the
connectors provided on the break-off sections. The board can be operated at 3V or 5V dc, which must be
provided by an external, regulated power supply.
The PCB has been laid out for both CTR21 and FCC68 compliant DAA designs. However the
components fitted are for the simplified European/FCC68 design. Users wishing to convert to CTR21
should contact CML.
2004 CML Microsystems Plc
CMLMICRO [ CML MICROCIRCUITS ]
