UART Simplifies Hardware Design

Exar Corp.8, an octal (eight-channel) 3.3V Universal Asynchronous Receiver Transmitter (UART), has applications in a wide range of high-performance systems including network management, hubs and routers, remote access servers, factory automation and process control, point-of-sale, and multi-serial-port communications add-on cards.

The device is said to offer new features not found in competitive solutions, or in earlier Exar product generations. The 3.3V power supply operation, with 5V tolerant inputs, offers flexibility in low-power system designs. Utilization of a single interrupt output, and global interrupt status registers for all eight channels, simplifies hardware and software driver development. The establishment of RS-485 half-duplex direction control with programmable turn-around delay eliminates unnecessary external logic (reduces systems costs). The support for Intel and Motorola 8-bit data bus interface simplifies hardware design and reduces design cycles.

Exar Corp.8 is a highly-integrated octal UART that is designed for the growing high-bandwidth requirements of telecommunication systems. The new global interrupt output pin, with global interrupt source registers, provides complete status on all eight channels which speeds up interrupt parsing. The global interrupt source registers are designed to make the software device drivers more efficient thus reducing CPU's bandwidth requirement in multi-channel systems.

In addition, the device has individual UART channel control, software-reset and simultaneous register initialization. It also offers RTS/CTS, or DTR/DSR hardware flow control with 16-selectable hysteresis, and software (Xon/Xoff) flow control with detection indicators. Furthermore, it provides RS-485 half-duplex direction control output with programmable turn-around time delay ranging from 0-bit to 15-bit. This is required for compensating signal propagation delay in long cabling networks. The device has 64-byte transmit and receive FIFOs (first-in, first-out) as well as FIFO level counters, programmable TX and RX FIFO trigger levels. Also, the device supports serial data rates of up to 6.25 Mbps, and has Infrared (IrDA 1.0) data encoder/decoder capabilities.

In 1,000 piece quantities, Exar Corp.8CQ device is priced at approximately $18.00 (pricing at time of publication).

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