General 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 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 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.


  • 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 Teridian 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
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