XRT4500 Datasheet, PDF (40/99 Pages) Exar Corporation – MULTIPROTOCOL SERIAL NETWORK INTERFACE IC

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XRT4500
MULTIPROTOCOL SERIAL NETWORK INTERFACE IC
REV. 1.0.7
1.0 SYSTEM DESCRIPTION
The XRT4500 Multi-protocol Serial Network Interface
IC is a flexible transceiver chip that is capable of sup-
porting the following “Communication Interfaces”.
• ITU-T V.35
• ITU-T V.28/EIA-232
• EIA-449
• ITU-T V.36
• ITU-T X.21
• EIA-530
• EIA-530A
The XRT4500 uses the following “electrical interfac-
es” in order to realize each of these “Communication
Interfaces”.
• ITU-T V.11/EIA-422
• ITU-T V.10/EIA-423
• ITU-T V.35
• ITU-T V.28/EIA-232
1.1 THE DIFFERENCE BETWEEN AN ELECTRI-
CAL INTERFACE AND A COMMUNICATIONS
INTERFACE
It is important to describe the difference between an
Electrical Interface specification and a Communica-
tions Interface specification. An Electrical Interface
specification defines the electrical characteristics of a
transmitter or receiver. These characteristics include
voltage, current, impedance levels, rise/fall times and
other similar parameters. Examples of electrical inter-
faces are ITU-T V.10 (EIA-423), ITU-T V.11 (EIA-
422), V.35 and V.28 (EIA-232).
In contrast, a Communications Interface specification
describes a “Physical Layer” interface in its entirety.
This description includes the names and functions of
all of the involved signals. The Communications Inter-
face specification identifies which electrical interface
is to be used to realize each of these signals as well
as the connector type. Examples of communication
interface types include ITU-T V.35, ITU-T V.28 (EIA-
232), EIA-449, EIA-530A, ITU-T X.21, and ITU-T
V.36.
For example, the “ITU-T V.35 Communications Inter-
face” specification requires that each of the following
signals must comply with the “ITU-T V.35 Electrical
Interface” requirements.
• RXD - Receive Data (CCITT Circuit 104)
• TXD - Transmit Data (CCITT Circuit 103)
• RXC - Receive Clock (CCITT Circuit 115)
• TXC - Transmit Clock (CCITT Circuit 114)
• SCTE (or TXCE) - Transmit Clock Echo
Also, the ITU-T V.35 Communications Interface speci-
fication states that each of the following signals must
comply with the “ITU-T V.28 Electrical Interface” re-
quirements.
• RTS - Request to Send (CCITT Circuit 105)
• CTS - Clear to Send (CCITT Circuit 106)
• DTR - Data Terminal Ready
• DSR - Data Set Ready (CCITT Circuit 107)
• DCD - Data Carrier Detect (CCITT Circuit 109)
• RL - Remote Loop-back Indicator*
• LL - Local Loop-back Indicator*
• TM - Test Mode Indicator*
NOTE: *Option Signals, per the “ITU-T V.35 Electrical Interface”
Finally, the “ITU-T V.35 Communications Interface”
recommends the use of the ISO-2593 34 pin Connec-
tor. (See Figure 46 connector drawings on page 73).
The XRT4500 contains a sufficient number of receiv-
ers, transmitters and transceivers to transport all of
the signals required for each of the above-mentioned
Communication Interface standards. By configuring
the XRT4500 to operate in a particular “Communica-
tion Interface” Mode, each of the Transmitters and
Receivers will automatically be configured to support
the appropriate “Electrical Interface” requirements.
Table 3 and Table 4 present the relationship between
the Communication Interface Mode that the
XRT4500 has been configured to operate in and the
corresponding Electrical Interface Mode that a giv-
en Transmitter or Receiver will be automatically con-
figured in.
Table 3 presents this information for the XRT4500
configured to operate in the DTE Mode. Table 4 pre-
sents this information when the XRT4500 has been
configured to operate in the DCE Mode.
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