XRT83VSH28ES Exar, XRT83VSH28ES Datasheet - Page 37

• 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
Telecommunication system design requires signal integrity and reliability. When an E1 primary line card has a
failure, it must be swapped with a backup line card while maintaining connectivity to a backplane without losing
data. System designers can achieve this by implementing common redundancy schemes with the
XRT83VSH28 LIU. EXAR offers features that are tailored to redundancy applications while reducing the
number of components and providing system designers with solid reference designs.
RLOS and DMO
If an RLOS or DMO condition occurs, the XRT83VSH28 reports the alarm to the individual status registers on a
per channel basis. However, for redundancy applications, an RLOS or DMO alarm can be used to initiate an
automatic switch to the back up card. For this application, two global pins RLOS and DMO are used to indicate
that one of the 8-channels has an RLOS or DMO condition.
Typical Redundancy Schemes



The 1:1 facility protection and 1+1 line protection have one backup card for every primary card. When using
1:1 or 1+1 redundancy, the backup card has its transmitters tri-stated and its receivers in high impedance. This
eliminates the need for external relays and provides one bill of materials for all interface modes of operation.
For 1+1 line protection, the receiver inputs on the backup card have the ability to monitor the line for bit errors
while in high impedance. The transmit and receive sections of the LIU device are described separately.
The transmitters on the backup card should be tri-stated. Select the appropriate impedance for the desired
mode of operation. A 0.68uF capacitor is used in series with TTIP for blocking DC bias. See
simplified block diagram of the transmit section for a 1:1 and 1+1 redundancy.
F
4.2
4.2.1
4.2.2
IGURE
1:1 One backup card for every primary card (Facility Protection)
1+1 One backup card for every primary card (Line Protection)
·N+1 One backup card for N primary cards
23. S
Line Card Redundancy
1:1 and 1+1 Redundancy Without Relays
Transmit Interface with 1:1 and 1+1 Redundancy
IMPLIFIED
B
LOCK
Backplane Interface
D
IAGRAM OF THE
Internal Impedence
Backup Card
Primary Card
Internal Impedence
Tx
Tx
T
RANSMIT
8-CHANNEL E1 SHORT-HAUL LINE INTERFACE UNIT
0.68uF
0.68uF
34
XRT83VSH28
XRT83VSH28
I
NTERFACE FOR
1:2
1:2
E1 Line
1:1
AND
1+1 R
EDUNDANCY
XRT83VSH28
Figure
23. for a