GENERAL DESCRIPTION

The EXAR Dual Universal Asynchronous Receiver and Transmitter (DUART) is a data communications device that provides two fully independent full duplex asynchronous communication channels in a single package. The DUART is designed for use in microprocessor based systems and may be used in a polled or interrupt driven environment.

The XR88C681 device offers a single IC solution for the 8080/85, 8086/88, Z80, Z8000, 68xx and 65xx microprocessor families.

FEATURES

● Two Full Duplex, Independent Channels

● Asynchronous Receiver and Transmitter

● Quadruple-Buffered Receivers and Dual Buffered Transmitters

● Programmable Stop Bits in 1/16 Bit Increments

● Internal Bit Rate Generators with More than 23 Bit Rates

● Independent Bit Rate Selection for Each Transmitter and Receiver

● External Clock Capability

● Maximum Bit Rate: 1X Clock - 1Mb/s, 16X Clock - 125kb/s

● Normal, AUTOECHO, Local LOOPBACK and Remote LOOPBACK Modes

● Multi-function 16 Bit Counter/Timer

● Interrupt Output with Eight Maskable Interrupt Conditions

● Interrupt Vector Output on Acknowledge (40 Pin DIP and 44 Pin PLCC Packages Only)

● Programmable Interrupt Daisy Chain

● 8 General Purpose Outputs (40 Pin DIP and 44 Pin PLCC Packages Only)

● 7 General Purpose Inputs with Change of States Detectors on Inputs (40 Pin DIP and 44 Pin PLCC Packages Only)

● Multi-Drop Mode Compatible with 8051 Nine Bit Mode

● On-Chip Oscillator for Crystal

● Standby Mode to Reduce Operating Power

● Compatible with the Motorola MC2681 and Signetics SCC2692 devices

● Advanced CMOS Low Power Technology

APPLICATIONS

● Multimedia Systems

● Serial to Parallel/Parallel to Serial Converter

● DTE for Modem Communication Systems