XRT75R12 Datasheet, PDF (82/89 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR

XRT75R12
REV. P1.0.2
PRELIMINARY
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
BIT NUMBER
2
NAME
E3_n
1
STS-1/DS3_n
0
SR/DR_n
TYPE
DESCRIPTION
R/W E3 Mode Select - Channel_n:
This READ/WRITE bit-field, along with Bit 1 (STS-1/DS3_n) within this
register, is used to configure a given channel into either the DS3, E3
or STS-1 Modes.
0 - Configures Channel_n to operate in either the DS3 or STS-1
Modes, depending upon the state of Bit 1 (STS-1/DS3_n) within this
same register.
1- Configures Channel_n to operate in the E3 Mode.
R/W STS-1/DS3 Mode Select - Channel_n:
This READ/WRITE bit-field, along with Bit 2 (E3_n) is used to config-
ure a given channel into either the DS3, E3 or STS-1 Modes.
This bit-field is ignored if Bit 2 (E3_n) has been set to "1".
If Bit 2 (E3_n) is a 0:
0 - Configures Channel_n to operate in the DS3 Mode.
1 - Configures Channel_n to operate in the STS-1 Mode .
R/W Single-Rail/Dual-Rail Select - Channel_n:
This READ/WRITE bit-field is used to configure Channel_n to operate
in either the Single-Rail or Dual-Rail Mode.
If the user configures the Channel to operate in the Single-Rail Mode,
the following will happen.
• The B3ZS/HDB3 Encoder and Decoder blocks (within Channel_n)
will be enabled.
• The Transmit Section of Channel_n will accept all of the outbound
data (from the System-side Equipment) via the TxPOS_n input pin.
• The Receive Section of each channel will output all of the recovered
data (to the System-side Equipment) via the RxPOS_n output pin.
• The corresponding RNEG/LCV_n output pin will now function as the
LCV (Line Code Violation or Excessive Zero Event) indicator output
pin for Channel_n.
If the user configures Channel_n to operate in the Dual-Rail Mode, the
following will happen.
• The B3ZS/HDB3 Encoder and Decoder blocks of Channel_n will be
disabled.
• The Transmit Section of Channel_n will be configured to accept
positive-polarity data via the TxPOS_n input pin and negative-
polarity data via the TxNEG_n input pin.
• The Receive Section of Channel_n will pulse the RxPOS_n output
pin "High" (for one period of RCLK_n) for each time a positive-
polarity pulse is received via the RTIP_n/RRING_n input pins.
Likewise, the Receive Section of each channel will pulse the
RxNEG_n output pin "High" (for one period of RxCLK_n) for each
time a negative-polarity pulse is received via the RTIP_n/RRING_n
input pins.
0 - Configures Channel_n to operate in the Dual-Rail Mode.
1 - Configures Channel_n to operate in the Single-Rail Mode.
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