DAN-125 Datasheet, PDF (2/2 Pages) Exar Corporation – EXAR’S XR16L784 COMPARED

ter. This is to ensure that the first character is not accidentally interpreted as a software flow control
character if it was not meant to be. The Automatic 2 character Flow Control provides a much more reli-
able mechanism. Only the SC28L194 has the Automatic 1 character Xon/Xoff Software Flow Control.
The SC28C94 does not have Automatic Xon/Xoff Software Flow Control.
• The XR16L784 has an Automatic RS485 Half-Duplex Control that will automatically control the direction
of the RS485 transceivers. When data is loaded into the FIFO, the RTS# pin will become a logic 1 for
transmit and when it is done transmitting all of the characters in the FIFO, it will change to a logic 0 so
that it can start receiving. This feature saves CPU bandwidth from a lot of software code manipulation.
This feature is not available in the Philips QUARTs.
• For wireless and portable applications, the XR16L784 has a built-in Infrared Data Association (IrDA)
encoder/decoder (ver 1.0). The Philips QUARTs do not have this feature.
• The XR16L784 has a sleep mode with automatic wake-up. Similarly, the SC28C94 and SC28L194 have
a Power Down Mode.
1.3 CONCLUSION
The XR16L784 is a much simpler device to design than the SC28C94 and SC28L194 because the register
set is compatible to the industry standard 16C550 register set. Since it is able to do simultaneous writes to
all the channels, the initialization of the XR16L784 is much easier and quicker than the SC28C94 and
SC28L194. With 64 bytes of TX and RX FIFO and a Global Interrupt Source Register, data throughput is
increased and the interval between interrupts are decreased reducing CPU bandwidth requirement. In ad-
dition to that, the XR16L784 has many enhanced features for increased performance that are not available
in the SC28C94 and SC28L194 as mentioned above in the Firmware Differences section.
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order
to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of
any circuits described herein, conveys no license under any patent or other right, and makes no represen-
tation that the circuits are free of patent infringement. Charts and schedules contained here in are only for
illustration purposes and may vary depending upon a user’s specific application. While the information in
this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where
the failure or malfunction of the product can reasonably be expected to cause failure of the life support sys-
tem or to significantly affect its safety or effectiveness. Products are not authorized for use in such applica-
tions unless EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury
or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corpo-
ration is adequately protected under the circumstances.
Copyright 2002 EXAR Corporation
June 2002
Send your UART technical inquiry with technical details to hotline: [e-mail]
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
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