78P2343JAT
3-port E3/DS3/STS-1 LIU
with Jitter Attenuator
LOCAL LOOPBACK AND REDUNDANCY MUX
Receivers 1 and 2 have a 4-input MUX as shown in
the adjacent figure. In multiport applications where
redundant channels are required, the receiver MUX
can be configured to provide the necessary
multiplexing functions. This allows the user to use
one port as a redundant monitor for the other port.
The tables below show the register settings for
selecting the desired receiver input source.
LLBKA
(Port 1)
0
0
1
1
LLBKA
(Port 2)
0
0
1
1
LLBKB
(Port 1)
0
1
0
1
LLBKB
(Port 2)
0
1
0
1
LLBKB
(Port 3)
0
1
Receiver #1 Input
Source
LINP1/LINN1
LOUTP1/LOUTN1
LINP2/LINN2
LOUTP2/LOUTN2
LOUTP3, LOUTN3
LOUTP1, LOUTN1
Transmitter
#1
00
01
10
11
LINP1, LINN1
Receiver
#1
LLBKA,B(1)
LOUTP2, LOUTN2
Transmitter
#2
00
01
10
11
LINP2, LINN2
Receiver
#2
LLBKA,B(2)
Receiver #2 Input
Source
LINP2/LINN2
LOUTP2/LOUTN2
LINP1/LINN1
LOUTP1/LOUTN1
Receiver #3 Input
Source
LINP3/LINN3
LOUTP3/LOUTN3
Transmitter
#3
0
1
LINP3, LINN3
Receiver
#3
LLBKB(3)
When serial interface control is not available, the
respective LPBKx pin for each of the channels can
also be used to activate local loopback mode as
shown below. Note that redundant channel modes
can only be activated using the serial interface.
LPBKx
pin
L
Z
H
Loopback Mode
Normal Operation
Same as LLBKA,B = ‘00’
Remote (Digital) Loopback
Same as RLBK = ‘1’
Local (Analog) Loopback
Same as LLBKA,B = ‘01’
Note: The LLBKA and LLBKB bits are located in the
Mode Control Register (MDCR).
The Register
Control bit, REGEN, should be enabled when using
the register settings to avoid conflict with external
loopback setting pins.
Page 3 of 37
2005 Teridian Semiconductor Corporation
Rev 2.2
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
