CH1794A Cermetek Microelectronics, CH1794A Datasheet - Page 2

• Manufacturer Part Number: CH1794A
• Manufacturer: Cermetek Microelectronics

Specifications of CH1794A

• Lead Free Status / RoHS Status: Not Compliant

Cermetek Microelectronics, Inc.
the DTE step up or step down in speed based on the
in-coming or out-going PSTN communication data
rate. Hence, the DTE can train the CH2056A, to say
56kbps, and talk to a slower in-coming data
connection at say, 2400bps without changing host
speed. Conversely, the host DTE trained at 14.4kbps
can also communicate with the modems at higher
speeds, say 28.8kbps.
invoking internal automatic data flow control. The HS
Modem family has a resident buffer to allow for this
auto baud operation.
Figure 1. Functional Block Diagram of HS Modem
Family.
Non-Volatile RAM (NVRAM).
user-customized
command will store the active modem configuration in
one of two NVRAM locations as selected by an n of 0
or 1. The AT&Yn command selects one of the stored
modem configurations to be automatically recalled and
made active upon reset or power up.
command immediately recalls and activates a stored
configuration. See Table 6 for storable S-Registers
and Commands.
The NVRAM can save up to four telephone numbers,
with up to 31 digits or modifiers in each telephone
number.
telephone number dial string. The ATDS=n command
will cause the modem to dial one of the four stored
telephone numbers. The NVRAM storage location for
the four telephone numbers is selected by an n of 0, 1,
2, or 3.
Telephone Line Interface or DAA. High performance
modems are extremely sensitive to DAA (Data Access
Arrangement) performance. The difference between a
good modem and a fair one is in the DAA
performance.
unique low distortion DAA designed for optimal
performance over all PSTN line conditions thereby
achieving the most reliable and best performance
PSTN connections.
2007 Cermetek Microelectronics, Inc.
The AT&Zn=s command will store s, the
The HS Modem family includes a
configurations.
This is accomplished by
NVRAM can store
The
The ATZn
AT&Wn
Page 2
The HS Modem family is designed to meet North
American telephone standards as set by the FCC Part
68 (USA) and CSA CS-03 Part I (Canada). Among the
more critical parameters, the PSTN line interface is
designed to meet 1500 VAC RMS isolation and
provide 2122V peak surge protection. Consequently,
the HS Modem family of products satisfies U.S. and
Canadian
international
specify these levels of isolation.
Pins 1 and 2 function as both input and output
connections to the PSTN. To maximize field reliability
in hostile environments, for Canadian approval, for UL
compliance, and also optionally for FCC Part 15
compliance, these two pins must be routed through an
external network such as that briefly described in
Figure 6A and described in more detail in Cermetek
Application Note # 126.
Each HS Modem product comes with FCC Part 68
approval and is shipped from the factory with an FCC
Label indicating registration number and ringer
equivalent. This label should be prominently displayed
on the end product. Canadian approval for CH1799A
is listed on page 1.
products in Cermetek’s High Speed Modem Family are
available upon request. With the exception of the U.S.
and Canada, most countries require submission of the
final product or system containing the HS Modem to
the appropriate governing regulatory agency for
approval. Typically this is accomplished by submitting
the final end product to an independent test house or
consultant for evaluation. The test house/consultant
then
documents to the regulatory agency.
Cermetek for a list of suggested consultants.
Modulation/Demodulation/Error
Data Compression. These functions are provided by
an industry standard modem chip set which has been
adapted for use with the HS Modem family.
Modulation/Demodulation
equalization, forward error correction and the industry
modem standards listed below.
CH179XA/2056A High Speed Family of Ultra Small Modems
SUPPORTED MODULATION STANDARDS
forwards
requirements,
approval
Bell 103
Bell212A
the
Document No. 607-0020 Revision B (01/07)
test
Canadian approvals for other
agency
scheme
and
results
ITU-T V.22
ITU-T V.22bis
ITU-T V.32
ITU-T V.32bis
ITU-T V.34
ITU-T V.34bis
ITU-T V.90
ITU-T V.92
requirements
will
Correcting
and
supports
meet
applicable
Contact
other
and
The
that
line