General Description

The 73K324L is a highly integrated single-chip modem IC which provides the functions needed to design a Quad-mode CCITT and Bell 212A compatible modem capable of operation over dial-up lines. The 73K324L adds V.23 capability to the CCITT modes of Teridian Semiconductor Corporation’s 73K224 one-chip modem, allowing a one-chip implementation in designs intended for European markets which require this added Modulation mode. The 73K324L offers excellent performance and a high level of functional integration in a single IC. The device supports V.22bis, V.22, Bell 212A, V.21, and V.23 operating modes, allowing both synchronous and asynchronous operation as defined by the appropriate standard.

The 73K324L is designed to appear to the Systems Engineer as a microprocessor peripheral, and will easily interface with popular one-chip microcontrollers (80C51 typical) for control of modem functions through its 8-bit multiplexed address/data bus. A serial control bus is available for applications not requiring a parallel interface. An optional package with only the serial control bus is also available. Data communications occurs through a separate serial port.

The 73K324L offers full hardware and software compatibility with other products in Teridian Semiconductor’s K?Series family of single-chip modems, allowing system upgrades with a single component change. The 73K324L is ideal for use in free-standing or integral system modem products where full-duplex 2400 bit/s operation with Alternate mode capability is required. Its high functionality, low power consumption, and efficient packaging simplify design requirements and increase system reliability. A complete modem requires only the addition of the phone line interface, a control microprocessor, and RS-232 level converters for a typical system.

The 73K324L is designed to provide a complete V.22bis, V.22, Bell 212A, V.21, and V.23 compatible modem on a chip. Many functions were included to simplify implementation in typical modem designs. In addition to the basic 2400 bit/s QAM, 1200/600 bit/s DPSK and 1200/300/75 bit/s FSK modulator/demodulator sections, the device also includes synch/asynch buffering, DTMF, answer, soft carrier, guard, and calling tone generator capabilities. Handshake pattern detectors simplify control of connect sequences, and precise tone detectors allow accurate detection of call progress, answer, calling, and soft carrier turn off tones. All Operating modes defined by the incorporated standards are included, and Test modes are provided. Most functions are selectable as options, and logical defaults are provided. The device can be directly interfaced to a microprocessor via its 8-bit multiplexed address/data bus for control and status monitoring. Data communications takes place through a separate serial port. Data may also be sent and received through the control registers. This simplifies designs requiring speed buffering, error control and compression.


  • One chip Multi-mode CCITT V.22bis, V.22, V.21, V.23 and Bell 212A compatible modem data pump
  • FSK (75, 300, 1200 bit/s), DPSK (600, 1200 bit/s), or QAM (2400 bit/s) encoding
  • Pin and software compatible with other Teridian Semiconductor Corporation K-Series family one-chip modems
  • Interfaces directly with standard microprocessors (8048, 80C51 typical)
  • Serial and parallel microprocessor bus for control
  • Selectable asynch/synch with internal buffer/debuffer and scrambler/descrambler functions
  • All synchronous (internal, external, slave) and Asynchronous Operating modes
  • Adaptive equalization for optimum performance over all lines
  • Programmable transmit attenuation (16 dB, 1 dB steps), and selectable receive boost (+18 dB)
  • Call progress, carrier, answer tone, unscrambled mark, S1, and signal quality monitors
  • DTMF, answer, calling, SCT and guard tone generators
  • Test modes available: ALB, DL, RDL; Mark, Space and Alternating bit pattern generators
  • CMOS technology for low power consumption (100 MW @ 5 V) with power-down mode(15 mW @ 5V)
  • 4-wire full duplex operation in all modes