Four-channel PCI UART broadens design options

Exar has expanded its family of universal asynchronous receiver transmitters (UARTs), with the XR17C154, quad (four-channel), PCI-based communications device.

Exar has expanded its family of universal asynchronous receiver transmitters (UARTs), with the XR17C154, quad (four-channel), PCI-based communications device.

Second in the series, it is compliant with industry specifications, and is aimed at remote access servers, network management, factory automation and process control.

"The XR17C154 follows the successful launch, and positive market response from last year's octal (eight-channel) version XR17C158", said Dr Roubik Gregorian, senior vice president, general manager, Exar Communication Division, and Exar's chief technology officer.

"With this new device, customers now have a wider range of design options".

The device provides a number of capabilities that are well suited for its market.

The XR17C154 supports 5V bus system designs at full 33MHz clock speed, and allows direct interface to the system bus without buffers.

This capability can both reduce the system cost and board space.

In addition, it has a 32bit global interrupt source register that will monitor and report: which UART channel has an interrupt service, and which UART channel transmitter or receiver requires attention.

This feature increases the efficiency of the operating system's device driver.

Also, the automatic RS485 half-duplex direction control with programmable turn-around delay feature simplifies hardware and software design, and compensates for signal propagation delay in network installations with long cable lengths.

The XR17C154 enables the transfer of more databytes in each interrupt service thus reducing CPU bandwidth requirements.

The RTS/CTS or DTR/DSR automatic hardware and software flow control feature maximizes data throughput for higher system performance, and automatic RTS/CTS flow control with hystersis further increases data transfer.

The internal registers include the industry standard 16CC550, and Exar's enhanced registers for the additional requirements of today's datacomms market.

The XR17C154 has selectable TX and RX FIFO trigger levels, and wireless infrared (IrDA) encoder/decoder, device identification, and sleep mode wake indicator.

The device has 64byte of TX and RX FIFOs in each UART channel, and is capable of operating up to serial datarates of 3Mbit/s.

Samples of the XR17C154, offered in a 144-pin TQFP package, supporting commercial and industrial ranges are available now.

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