General Description

The 73K222AU is a compact, high-performance modem which includes a 8250A/16C450 compatible UART with the 1200 bit/s modem function on a single chip. Based on the 73K222L 5V low power CMOS modem IC, the 73K222AU is the perfect modem/UART component for integral modem applications. It is ideal for applications such as portable terminals and laptop computers. The 73K222AU is the first fully featured modem IC which can function as an intelligent modem in integral applications without requiring a separate dedicated microcontroller. It provides for data communication at 1200, 600, and 300 bit/s in a multi-mode manner that allows operation compatible with both Bell 212A/103 and CCITT V.22/V.21 standards. The digital interface section contains a high speed version of the industry standard 8250A/16C450 UART, commonly used in personal computer products. A unique feature of the 73K222AU is that the UART section can be used without the modem function, providing an additional asynchronous port at no added cost. The 73K222AU is designed in CMOS technology and operates from a single +5V supply. Available in a 44-pin PLCC package.


  • Modem/UART combination optimized for integral bus applications
  • Includes features of 73K222L single-chip modem
  • Fully compatible 16C450/8250 UART with 8250B or 8250A selectable interrupt emulation
  • High speed UART will interface directly with high clock rate bus with no wait states
  • Single-port mode allows full modem and UART control from CPU bus, with no dedicated microprocessor required
  • Dual-port mode suits conventional designs using local microprocessor for transparent modem operation
  • Complete modem functions for 1200 bit/s (Bell 212A, V.22) and 0-300 bit/s (Bell 103, V.21)
  • Includes DTMF generator, carrier, call-progress and precise answer-tone detectors for intelligent dialing capability
  • On chip 2-wire/4-wire hybrid driver and off-hook relay buffer
  • Speaker output with four-level software driven volume control
  • Low power CMOS (40 mW) with power down mode (15 mW)
  • Operates from single +5V supply



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