73K222AU
Single-Chip Modem
Modem with UART
April 2000
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 packaging includes 40-pin DIP or
44-pin PLCC for surface mount applications.
FEATURES
• 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
BLOCK DIAGRAM
UD0
UD1
UD2
UD3
UD4
UD5
UD6
UD7
UA0
UA1
UA2
INTRPT ( ) PRST RESET RXD
INT OUT1
VDD VREF GND ISET STNDLN
( ) /
( ) / DCLK
/ (N/C)
/ ( )
DATA / ( )
(UA3) / MA2
( ) / MA1
( ) / MA0
SPKR
RXA
TXA2
TXA1
CLKXTL2XTL1TXD
1.8432 MHz
INTERNAL DATA
8250A / 16C450
UART
73K222AL
2W/4W
HYBRID
2
RELAY
DRIVER
RXD-INPUT OH