78P2344JAT
4-port E3/DS3/STS-1 LIU
with Jitter Attenuator
LOCAL LOOPBACK AND REDUNDANCY MUX
Transmitter
#1
Each receiver has 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.
LOUTP1, LOUTN1
LINP1, LINN1
00
Receiver
01
10
11
#1
LLBKA,B(1)
Transmitter
#2
LOUTP2, LOUTN2
LINP2, LINN2
LLBKA
LLBKB
Receiver #1 Input
Source
(Port 1)
(Port 1)
00
01
10
11
Receiver
0
0
1
1
0
1
0
1
LINP1/LINN1
LOUTP1/LOUTN1
LINP2/LINN2
#2
LLBKA,B(2)
LOUTP2/LOUTN2
Transmitter
#3
LOUTP3, LOUTN3
LINP3, LINN3
LLBKA
LLBKB
Receiver #2 Input
Source
LINP2/LINN2
LOUTP2/LOUTN2
LINP1/LINN1
LOUTP1/LOUTN1
00
(Port 2)
(Port 2)
01
10
11
Receiver
#3
0
0
1
1
0
1
0
1
LLBKA,B(3)
Transmitter
#4
LOUTP4, LOUTN4
LINP4, LINN4
LLBKA
LLBKB
Receiver #3 Input
Source
LINP3/LINN3
LOUTP3/LOUTN3
LINP4/LINN4
LOUTP4/LOUTN4
00
01
10
(Port 3)
(Port 3)
Receiver
#4
11
0
0
1
1
0
1
0
1
LLBKA,B(4)
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.
LLBKA
LLBKB
Receiver #4 Input
Source
(Port 4)
(Port 4)
0
0
1
1
0
1
0
1
LINP4/LINN4
LOUTP4/LOUTN4
LINP3/LINN3
LPBKx
Loopback Mode
pin
Normal Operation
Same as LLBKA,B = ‘00’
LOUTP3/LOUTN3
L
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.
Z
H
Page 3 of 37
2005 Teridian Semiconductor Corporation
Rev 2.2
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
