CH1788
Surface Mount PLCC 2400bps Modem
2006 Cermetek Microelectronics, Inc.
Page 1
Document No. 607-0018 Revision A6 (01/06)
INTRODUCTION
The CH1788 modem has the smallest footprint and
lowest profile of any commercially available full
function, FCC Part 68 approved 2400bps modem.
Utilizing a 68 pin PLCC form factor and requiring a
minimum amount of PCB space (0.95”x0.95”x
0.255”), the CH1788 affords the design engineer
maximum flexibility. The CH1788 provides two
external interfaces: a ITU-T V.24 standard 5 volt
serial interface for routing directly to a UART; and a
TIP and RING interface for connection to the PSTN
telephone line. The CH1788 is compatible with
available industry communication software or may be
controlled with software commands via an embedded
microcontroller.
The CH1788 modem supports asynchronous
operation at 2400bps, 1200bps, and 300bps to both
Bell and ITU-T standards. Each device is FCC
approved and Canadian DOT approvable. An FCC
label is supplied. The CH1788 also meets UL 1950
Edition 3 requirements.
The CH1788 family of modems operate from a 5 volt
DC supply (3.3 volt devices are available by special
order). The combination of low power operation, zero
power standby mode and small form factor make the
CH1788 an ideal choice for portable equipment
applications.
Figure 1. Functional Block Diagram of CH1788.
FEATURES
•
Supports data rate standards, ITU-T V.22bis,V.22,
Bell 212, and Bell 103, Bell 202, V.23.
•
Fast
connect
handshaking.
•
FCC Part 68 approved.
•
CS-03 Industry Canada registered.
•
UL 1950 and CSA C22.2 950 Listed.
•
AT Command structure.
•
Speed buffered operation at: 9600, 2400, 1200
and 300bps.
•
Call progress tone detection.
•
Caller ID information.
•
Line In Use and Priority Pick Up 911 feature
support with external circuitry.
•
DTMF generation and detection resident on
CH1788.
•
5 volt operation/ 3.3 volt operation available.
•
Low power operation with automatic reduced
power idle and zero power standby modes.
•
Low profile PLCC surface mount packaging; fits
standard 68 pin PLCC socket.
•
Size: 0.95” x 0.95” x 0.255”(nominal).
CH1788 FAMILY
CH1788
Operating Temperature:
0
°
C to +70
°
C
CH1788ET
Operating
Temperature:
-40
°
C to +85
°
C
CH1788-3
3.3 volt Operation
Operating
Temperature:
0
°
C to +70
°
C
CH1788-3ET
3.3 volt Operation
Operating
Temperature:
-40
°
C to +85
°
C
DESCRIPTION OF FUNCTIONAL BLOCKS
AND DISCUSSION OF BASIC OPERATIONS
Figure 1 contains a functional block drawing of the
CH1788. The CH1788 is a highly integrated, full-
function modem, comprised of a modulator/
demodulator, controller, and an FCC Part 68
approved telephone line interface.
Modulation/Demodulation and Modem Controller.
This function is provided by a monolithic modem
integrated circuit. The function is performed to ITU-T
standards thereby making the CH1788 compatible
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