73K224BL
V.22bis, V.22, V.21, Bell 212A, 103
Single-Chip Modem w/ Integrated Hybrid
DATA SHEET
DESCRIPTION (continued)
FEATURES (continued)
•
•
•
Adaptive equalization for optimum perform-
ance over all lines
The 73K224BL is pin and software compatible with
the 73K222BL, allowing system upgrades with a
single component change.
Programmable transmit attenuation (16 dB,
1 dB steps), selectable receive boost (+18 dB)
The 73K224BL 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,
Call
progress,
carrier,
answer
tone,
unscrambled mark, S1, and signal quality
monitors
a
control microprocessor, and RS-232 level
converter 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
•
•
DTMF, answer and guard tone generators
Test modes available: ALB, DL, RDL, mark,
space, alternating bit, S1 pattern generation
and detection
includes
synch/asynch
converters,
scrambler/descrambler, call progress tone detect,
DTMF tone generator capabilities and handshake
pattern detectors. Test features such as analog loop,
digital loop, and remote digital loopback are
supported. Internal pattern generators are also
included for self-testing.
•
•
CMOS technology for low power consumption
(typically 100 mW @ 5 V) with power-down
mode (15 mW @ 5 V)
TTL and CMOS compatible inputs and outputs
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 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.
FUNCTIONAL DESCRIPTION
HYBRID AND RELAY DRIVER
To make designs more cost effective and space
efficient, the 73K224BL includes the 2-wire to 4-wire
hybrid with sufficient drive to interface directly to the
telecom coupling transformers. In addition, an off hook
relay driver with 30mA drive capability is also included
to allow use of commonly available mechanical
telecom relays.
QAM MODULATOR/DEMODULATOR
The 73K224BL encodes incoming data into quad-bits
represented by 16 possible signal points with specific
phase and amplitude levels. The base-band signal is
then filtered to reduce intersymbol interference on the
band limited 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.
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
FUNCTIONAL DESCRIPTION (continued)
(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
DPSK MODULATOR/DEMODULATOR
The 73K224BL modulates a serial bit stream into di-bit
pairs that are represented by four possible phase
Page: 2 of 33
© 2005, 2008 TERIDIAN Semiconductor Corporation
Rev 7.1
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