CH224ATF
Complete 2400 bps Modem Module
INTRODUCTION
The CH224ATF is a complete FCC Part 68 preapproved, 2400 bps full function modem solution;
incorporating an on-board Data Access
Arrangement (DAA) in a small footprint, socketable packaging format (2.5” L x 1.0 W x 0.45” H).
This product is specifically designed for use as a
direct replacement for Conexant/Rockwell’s
SocketModem (serial TTL I/O option, Part No.
SF224ATF-H1-D5-A0-P1
).
This modem provides a fast and convenient way
to integrate PSTN connectivity into any OEM
product while utilizing a small portion of PCB area.
The CH224ATF requires two external interfaces: a
CCITT V.24 serial interface that is routed directly
from the UART or UART interface, and a TIP and
RING interface, which is connected directly to a
conventional RJ-11 jack for the PSTN line
connection. The CH224ATF also has various
indicator and status lines to monitor operations or
to establish triggers. The CH224ATF modem is
controlled by industry standard “AT” commands
and is compatible with available industry
communication software.
The device supports asynchronous operation at
2400 bps, 1200 bps, and 300 bps to both Bell and
CCIT standards. The resident PSTN line interface
is FCC Part 68 approved, and is also Canadian
DOC approveable, and can be approved in other
countries that require 1500VAC RMS isolation.
Figure 1. Functional Block Diagram of
CH224ATF
FEATURES
• FCC Part 68 pre-approved
• UL1950, 3rd edition listed
• 1500 Vrms isolation
• Complete solution: on-board DAA
• Data modes
- CCITT v.22 bis (2400 bps), V.22 (1200
bps)
- Bell 212A (1200 bps) and 103 (300
bps)
- Enhanced AT commands
• Group 3 fax modes
- V.29 (6900/7200 bps) transmit
- V.27 ter (4800/2400 bps) transmit and
receive
- V.21 Channel 2 (300 bps) transmit
and receive
• EIA-578 Service Class 1 commands
• V.42/MNP2-4 and V.42 bis/MNP5 support
without additional hardware
• Data/fax discriminator and auto answering
• Communications software compatible
• Serial asynchronous DTE interface
• NVRAM interface allows storage of two
user configurations and four 36-digit dial
strings
• Automatic adaptive/fixed compromise
equalization
• Programmable sleep mode
• Full-duplex data mode test capabilities:
Analog loop, local digital loop, and remote
digital loop
• Half-duplex fax mode test capabilities
• Automatic format/speed sensing
• Low power consumption (typical):
Interface Operating Sleep
Serial TTL: 155mW 35mW
• Single +5VDC power supply
TECHNICAL SPECIFICATIONS
General
The CH224ATF modem is a full-featured, selfcontained data/fax solution. External microcontroller for data or fax control functions are
fully supported and controlled through the AT
command set.
2001 Cermetek Microelectronics, Inc. Page 1 Document No. 607-0005 Revision B1 (05/02)