73K224L Modem Datasheet

73K224L Datasheet, PDF, Equivalent


Part Number

73K224L

Description

Single-Chip Modem

Manufacture

TDK

Total Page 30 Pages
Datasheet
Download 73K224L Datasheet


73K224L
73K224L
V.22bis/V.22/V.21/ Bell 212A/Bell 103
Single-Chip Modem
DESCRIPTION
The 73K224L is a highly integrated single-chip
modem IC which provides the functions needed to
construct a V.22bis compatible modem, capable of
2400 bit/s full-duplex operation over dial-up lines. The
73K224L offers excellent performance and a high
level of functional integration in a single 28-pin DIP
and 44-pin TQFP package. This device supports
V.22bis, V.22, V.21, Bell 212A and Bell 103 modes of
operation, allowing both synchronous and
asynchronous communication. The 73K224L is
designed to appear to the systems designer as a
microprocessor peripheral, and will easily interface
with popular single-chip microprocessors (80C51
typical) for control of modem functions through its 8-
bit multiplexed address/data bus or via an optional
serial control bus. An ALE control line simplifies
address demultiplexing. Data communications
normally occur through a separate serial port. The
73K224L is pin and software compatible with the
73K212L and 73K222L single-chip modem ICs,
allowing system upgrades with a single component
change.
The 73K224L operates from a single +5V supply for
low power consumption.
The 73K224L is ideal for use in either free-standing or
integral system modem products where full-duplex
(continued)
BLOCK DIAGRAM
April 2000
FEATURES
One-chip multi-mode V.22bis/V.22/V.21 and Bell
212A/103 compatible modem data pump
FSK (300 bit/s), DPSK (600, 1200 bit/s), or QAM
(2400 bit/s) encoding
Pin and software compatible with other TDK
Semiconductor Corporation K-Series 1-chip
modems
Interfaces directly with standard microcontrollers
(80C51 typical)
Parallel microcontroller bus for modem control and
status monitoring functions
Selectable
asynch/synch
with
internal
buffer/debuffer and scrambler/descrambler
functions
All synchronous and asynchronous operating
modes (internal, external, slave)
Adaptive equalization for optimum performance
over all lines
Programmable transmit attenuation (16 dB, 1 dB
steps), selectable receive boost (+18 dB)
Call progress, carrier, answer tone, unscrambled
mark, S1, and signal quality monitors
DTMF, answer and guard tone generators
Test modes available: ALB, DL, RDL, Mark, Space,
Alternating bit, S1 pattern
CMOS technology for low power consumption
(typically 100 mW @ 5V) with power-down mode
(15 mW @ 5V)
TTL and CMOS compatible inputs and outputs

73K224L
73K224L
V.22bis/V.22/V.21/Bell 212A/Bell 103
Single-Chip Modem
DESCRIPTION (continued)
2400 bit/s data communications over the 2-wire
switched telephone network is desired. Its high
functionality, low power consumption, and efficient
packaging simplify design requirements and increase
system reliability.
The 73K224L is designed to be a complete V.22bis
compatible modem on a chip. The complete modem
requires only the addition of the phone line interface, a
microcontroller for modem control and status
monitoring, and RS-232 level converters for a typical
system. Many functions were included to simplify
implementation of typical modem designs. In addition
to the basic 2400 bit/s QAM, 600/1200 bit/s DPSK and
300 bit/s FSK modulator/demodulator sections, the
device also includes SYNCH/ASYNCH converters,
scrambler/descrambler, call progress tone detect,
DTMF tone generator capabilities and handshake
pattern detectors. V.22bis, V.22, V.21 and Bell
212A/103 modes are supported (synchronous and
asynchronous) and test modes are provided for
diagnostics. Most functions are selectable as options
and logical defaults are provided.
OPERATION
QAM MODULATOR/DEMODULATOR
The 73K224L encodes incoming data into quad-bits
represented by 16 possible signal points with specific
phase and amplitude levels. The baseband signal is
then filtered to reduce intersymbol interference on the
bandlimited telephone network. The modulator
transmits this encoded data using either a 1200 Hz
(originate mode) or 2400 Hz (answer mode) carrier.
The demodulator, although more complex, essentially
reverses this procedure while also recovering the data
clock from the incoming signal. Adaptive equalization
corrects for varying line conditions by automatically
changing filter parameters to compensate for line
characteristics.
DPSK MODULATOR/DEMODULATOR
The 73K224L modulates a serial bit stream into di-bit
pairs that are represented by four possible phase
shifts as prescribed by the Bell 212A/V.22 standards.
The base-band signal is then filtered to reduce
intersymbol interference on the bandlimited 2-wire
PSTN line. Transmission occurs on either a 1200 Hz
(originate mode) or 2400 Hz carrier (answer mode).
Demodulation is the reverse of the modulation
process, with the incoming analog signal eventually
2
decoded into di-bits and converted back to a serial
bit stream. The demodulator also recovers the
clock which was encoded into the analog signal
during modulation. Demodulation occurs using
either a 1200 Hz carrier (answer mode or ALB
originate mode) or a 2400 Hz carrier (originate
mode or ALB answer mode). Adaptive
equalization is also used in DPSK modes for
optimum operation with varying line conditions.
FSK MODULATOR/DEMODULATOR
The FSK modulator produces a frequency
modulated analog output signal using two discrete
frequencies to represent the binary data. The Bell
103 standard frequencies of 1270 and 1070 Hz
(originate mark and space) and 2225 and 2025 Hz
(answer mark and space) are used when this
mode is selected. V.21 mode uses 980 and 1180
Hz (originate, mark and space) or 1650 and 1850
Hz (answer, mark and space). Demodulation
involves detecting the received frequencies and
decoding them into the appropriate binary value.
The rate converter and scrambler/descrambler are
automatically bypassed in the FSK modes.
PASSBAND FILTERS AND EQUALIZERS
High and low band filters are included to shape the
amplitude and phase response of the transmit and
receive signals and provide compromise delay
equalization and rejection of out-of-band signals.
Amplitude and phase equalization are necessary
to compensate for distortion of the transmission
line and to reduce intersymbol interference in the
bandlimited receive signal. The transmit signal
filtering corresponds to a 75% square root of
raised Cosine frequency response characteristic.
ASYNCHRONOUS MODE
The Asynchronous mode is used for
communication with asynchronous terminals which
may communicate at 600,1200, or 2400 bit/s +1%,
-2.5% even though the modem’s output is limited
to the nominal bit rate ±.01% in DPSK and QAM
modes. When transmitting in this mode the serial
data on the TXD input is passed through a rate
converter which inserts or deletes stop bits in the
serial bit stream in order to output a signal that is
the nominal bit rate ±.01%. This signal is then
routed to a data scrambler and into the analog
modulator where quad-bit/di-bit encoding results in
the output signal. Both the rate converter and
scrambler can be bypassed for handshaking, and


Features 73K224L V.22bis/V.22/V.21/ Bell 212A/Bel l 103 Single-Chip Modem DESCRIPTION Th e 73K224L is a highly integrated single -chip modem IC which provides the funct ions needed to construct a V.22bis comp atible modem, capable of 2400 bit/s ful l-duplex operation over dial-up lines. The 73K224L offers excellent performanc e and a high level of functional integr ation in a single 28-pin DIP and 44-pin TQFP package. This device supports V.2 2bis, V.22, V.21, Bell 212A and Bell 10 3 modes of operation, allowing both syn chronous and asynchronous communication . The 73K224L is designed to appear to the systems designer as a microprocesso r peripheral, and will easily interface with popular single-chip microprocesso rs (80C51 typical) for control of modem functions through its 8bit multiplexed address/data bus or via an optional se rial control bus. An ALE control line s implifies address demultiplexing. Data communications normally occur through a separate serial port. The 73K224L is pin and software compatib.
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