1.8V high-speed DUARTS feature selectable TX and RX FIFO trigger levels and fractional baud rate generator

2006-09-28

Exar has announced a family of dual universal asynchronous receiver transmitters (DUARTS) that operate from a 1.62V to 3.63V supply and feature 16, 32 or 64-byte FIFOs. Designated the M-series, each channel of these devices is capable of data rates up to 16 MBps at 3.3V with a 4X sampling clock. They are all compatible with industry standard 16550 UARTs and provide a host of additional features including selectable TX and RX FIFO trigger levels, automatic hardware (RTS/CTS) flow control, automatic software (XON/XOFF) flow control, sleep mode, and a fractional baud rate generator. Some versions add a power save function that operates in sleep mode and isolates the address, data and control lines from the CPU to reduce sleep current to 15 µA.

The fractional baud rate generator is a new feature that provides a greater choice of clock or crystal frequency. It allows divisors from 1 to 215.9375 in steps of 0.0625. As a result, a non-standard clock frequency can be used to generate standard baud rates or a standard clock can generate non-standard baud rates.

Some versions, in all FIFO types, can operate in either Intel or Motorola bus modes.

M-series DUARTS are available in 48-TQFP and 32-QFN packages.