TDK Semiconductor Corporation 73D2348, 73D2248 Datasheet

73D2248A/2348A

MNP5, V.42bis Datacom

Modem Device Set

April 2000

DESCRIPTION

The 73D2248A/2348A Device Sets consists of two
CMOS integrated circuits which provide the data
pump and protocol functions required to implement a
high performance 2400 bit/s modem with error
control and data compression. The 73D2248A basic
modem function is provided by the 73K224L modem
chip and is compatible with CCITT V.21, V.22,
V.22bis and Bell 103 and 212A protocols. The error
control functions are provided by modular software
running in the 73M2910 controller. Modules are
available for MNP4, and V.42. Compression
software modules can be added to the controller;
MNP5 and V.42bis are available. Provisions for
customization of the command set are provided,
forming the basis for an international modem.

The 73D2348 differs from the 73D2248A in that it
uses the 73K324L instead of the 73K224L for the
data pump. The 73K324L replaces the Bell 103, 300
bps (bit/s) FSK mode of operation, with the CCITT
V.23, 1200 bps (bit/s) FSK mode. The software is
also modified to support V.23. The two products are
otherwise identical.

FEATURES

• Combines modem and protocol controller

• Supports 0 - 300, 1200 and 2400 bit/s with both

sync and async modes

• Modular software design allows customization

• Modem protocols:

• Bell 103 (73K224L), 212A

• CCITT V.21, V.22, V.22bis, V.23 (73K324L)

• Error control/compression protocols Available:

MNP4, MNP5, CCITT V.42, V.42bis

• Supports non-volatile memory to store user

configurations and phone numbers

• CMOS design for low power consumption

MNP5, V.42bis Datacom

Modem Device Set

RECOMMENDED

SUPPORT

TSC 73D2248

ROM

64K x 8

STATIC

RAM

32K x 8

73M2910L

Controller

NV

RAM

93C66

HYBRID/

DAA

73K224L/324L

Modem

8

16

16

73D2248A/2348A
MNP5, V.42bis Datacom
Modem Device Set

2

FUNCTIONAL DESCRIPTION

The 73D2248A /2348A device set forms the basis for
an international modem design incorporating the
most advanced error control and compression
algorithms. The set consists of two chips, the
73K224L (73K324L) modem and the 73M2910
controller. Customization of the controller is one of
the features of this device set; software modules
allow the modem vendor to provide a range of
features from a standard hardware platform.

The 73K224L (73K324L) provides the QAM, PSK
and FSK modulator and demodulator functions, call
progress and handshake tone monitors, test modes
and a tone generator capable of producing DTMF,
answer and CCITT guardtones. This single-chip
modem supports the V.22bis, V.22, V.21 and Bell
103/CCITT V.23/212A operating protocols in both
sync and async modes. Low level functions of the
controller provide for automatic detection of DTE
speed, auto-dial, auto-answer, handshake with
fallback and call progress detection.

The 73M2910 controller handles both the low level
modem functions as well as protocol negotiation and
protocol operation. Software modules can be
chosen to provide the desired protocols for product
customization and differentiation. In addition, the
“AT” command set source code will be available for
those desiring to provide unique or country
dependent features.

Basic capabilities of the modem are those found in
the 73K224L (73K324L) single-chip modem and are
listed in the separate 73K224L (73K324L) data
sheet.

AUTOMATIC HANDSHAKE

The 73D2248A/2348A will automatically perform a
complete handshake with a called or calling modem
and enter the data transfer mode. After the link
between the two modems has been established, the
modems may remain in the normal data mode or
negotiate a link which has error control and data
compression. Commands are provided to inform the
modem which action is appropriate.

TEST MODES

The 73D2248A /2348A device set has provisions for
three test modes: analog loopback, digital loopback
and remote digital loopback. Analog loopback
allows data to be sent into the local modem, have it
modulated and then demodulated and returned to
the local terminal. Digital loopback requires the
cooperation of the user at the remote end and allows
data to be sent to the remote modem, demodulated,
then remodulated and returned to the local end.
Remote digital loopback allows the same capability,
without the need for a remote operator; signals are
sent to the remote modem which perform the
switching task that a remote operator would have
done.

AT COMMAND INTERPRETER

The 73D2248A/2348A includes an AT Command
Interpreter which is a superset of the Hayes 2400

Smartmodem command set. Common application
software will be able to control the modem though
this interpreter. Additional commands have been
added to provide for control of the MNP and CCITT
V.42 modes.

NON-VOLATILE MEMORY

A serial NVRAM provides 256 bytes of storage for
configuration information and telephone numbers.

73D2248A/2348A

MNP5, V.42bis Datacom

Modem Device Set

3

PROTOCOLS

Microcom Networking Protocol (MNP)

MNP4 is a protocol offering error control while MNP5
offers data compression. Data to be transmitted is
broken into blocks of varying sizes, depending on
line conditions, and sent to the remote modem along
with a 16-bit Cyclic Redundancy Check (CRC) word.
If the algorithm used to derive the CRC word at the
transmitter does not produce an identical word when
exercised on the received data, a line error is
assumed, and the block is repeated. Data
compression is obtained by transmitting a short set
of characters for a longer redundant set. At the
receiver, the short string is replaced with the longer
string that it represented, and the data stream is
returned to its original state.

CCITT V.42 AND V.42BIS

The CCITT has ratified a set of protocols which
operate in a manner similar to MNP. MNP4
corresponds to V.42 while MNP5 corresponds with
V.42bis. Greater efficiency is offered, but the
tradeoff is a larger memory space requirement.
MNP5 requires an 8K buffer, while V.42bis requires
32K. Data files which show compression ratios
approaching 2:1 with MNP5 may show ratios of
nearly 4:1 with V.42bis.

ADDITIONAL INFORMATION

The TDK Semiconductor Corporation 73D2248/2348
Design Manual defines the AT commands. Please
contact your local TDK Semiconductor Corporation's
sales office for a copy of the TDK Semiconductor
Corporation's Protocol Design Manual.