XRT83VSH28ES Exar, XRT83VSH28ES Datasheet - Page 41

• Manufacturer Part Number: XRT83VSH28ES
• Description: Peripheral Drivers & Components - PCIs 8 CH E1 LIU SH (low cost version)
• Manufacturer: Exar

Specifications of XRT83VSH28ES

• Product Category: Peripheral Drivers & Components - PCIs
• Rohs: yes

REV. 2.0.0
For 1:1 or 1+1 line card redundancy in E1 applications, power failure could cause a line card to change the
characteristics of the line impedance, causing a degradation in system performance. The XRT83VSH28 was
designed to ensure reliability during power failures. The LIU has patented high impedance circuits that allow
the receiver inputs and the transmitter outputs to be in "High" impedance when the LIU experiences a power
failure or when the LIU is powered off.
N
Physical layer devices such as LIUs that interface to telecommunications lines are exposed to overvoltage
transients posed by environmental threats. An Overvoltage transient is a pulse of energy concentrated over a
small period of time, usually under a few milliseconds. These pulses are random and exceed the operating
conditions of CMOS transceiver ICs. Electronic equipment connecting to data lines are susceptible to many
forms of overvoltage transients such as lightning, AC power faults and electrostatic discharge (ESD). There are
three important standards when designing a telecommunications system to withstand overvoltage transients.



In non-intrusive monitoring applications, the transmitters are shut off by setting TxON "Low". The receivers
must be actively receiving data without interfering with the line impedance. The XRT83VSH28’s internal
termination ensures that the line termination meets E1 specifications for 75 or 120 while monitoring the
data stream. System integrity is maintained by placing the non-intrusive receiver in "High" impedance,
equivalent to that of a 1+1 redundancy application. A simplified block diagram of non-intrusive monitoring is
shown in
F
4.3
4.4
4.5
OTE
IGURE
UL1950 and FCC Part 68
Telcordia (Bellcore) GR-1089
ITU-T K.20, K.21 and K.41
: For power failure protection, a transformer must be used to couple to the line interface. See the TAN-56 application
note for more details.
27. S
Power Failure Protection
Overvoltage and Overcurrent Protection
Non-Intrusive Monitoring
Figure
IMPLIFIED
27.
B
XRT83VSH28
XRT83VSH28
LOCK
Non-Intrusive Receiver
Line Card Transceiver
D
IAGRAM OF A
N
ON
-I
NTRUSIVE
8-CHANNEL E1 SHORT-HAUL LINE INTERFACE UNIT
38
Data Traffic
M
ONITORING
A
PPLICATION
Node
XRT83VSH28