73K321L
CCITT V.23, V.21
Single-Chip Modem
April 2000
DESCRIPTION
The 73K321L is a highly integrated single-chip
modem IC which provides the functions needed to
construct a CCITT V.23 and V.21 compatible
modem, capable of 0-300 bit/s full-duplex or 0-1200
bit/s half-duplex operation over dial-up telephone
lines. The 73K321L provides 1200 bit/s operation in
V.23 mode and 300 bit/s in V.21 mode. The
73K321L also can both detect and generate the
2100 Hz answer tone needed for call initiation. The
73K321L integrates analog, digital, and switched-
capacitor array functions on a single substrate,
offering excellent performance and a high level of
functional integration in a single 28-pin DIP or PLCC
package. The 73K321L operates from a single +5V
supply with very low power consumption.
The 73K321L includes the FSK
modulator/demodulator functions, call progress and
handshake tone monitor test modes, and a tone
generator capable of producing DTMF, answer,
calling tones. The 73K321L is designed to appear to
the systems designer as a microprocessor
peripheral, and will easily interface with popular one-
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 occurs
through a separate serial port only.
(continued)
FEATURES
• One-chip CCITT V.23 and V.21 standard
compatible modem data pump
• Full-duplex operation at 0-300 bit/s (V.21) or
0-1200 bit/s (V.23) forward channel with or
without 0-75 bits/s back channel
• Full Duplex 0-1200 bit/s (V.23) in 4-wire mode
• Pin and software compatible with other TDK
Semiconductor Corporation K-Series 1-chip
modems
• Interfaces directly with standard micro-
processors (8048, 80C51 typical)
• Serial port for data transfer
• Call progress, carrier, precise answer tone
(2100 Hz), calling tone (1300 Hz) and FSK
mark detectors
• DTMF generator
• Test modes available: ALB, DL, RDL, Mark,
Space, Alternating bit patterns
• Precise automatic gain control allows 45 dB
dynamic range
• CMOS technology for low power
consumption using 60 mW @ 5V from a
single power supply
BLOCK DIAGRAM
DTMF &
TONE
GENERATORS
FSK
MODULATOR/
DEMODULATOR
SMART
DIALING
&
DETECT
FUNCTIONS
POWER
TESTS:
ALB,DLB
RDLB
PATTERNS
TRANSMIT
FILTER
DATA
BUS
BUFFER
READ
WRITE
CONTROL
LOGIC
STATUS
AND
CONTROL
LOGIC
8-BIT
BUS
FOR
CONTROL
AND
STATUS
SERIAL
PORT
FOR
DATA
TXA
RXA
ISET
VDD
VREF
GND
RXCLK
CLOCK
GENERATOR
XTL2
XTL1
CLK
TXCLK
EXCLK
RD
WR
ALE
CS
RESET
INT
TXD
RXD
AD0-AD7
RECEIVE
FILTER
