XRT72L58 Datasheet, PDF (34/486 Pages) Exar Corporation – EIGHT CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L58
EIGHT CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
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PRELIMINARY
PIN DESCRIPTION FOR THE XRT72L58
PIN #
G1
G2
PIN NAME
RxNEG[0]
TxInClk[7]
G3
RxLineClk[7]
G4
RxPOS[7]
G23
TxOHFrame[2]/
TxHDLCClk[2]
G24
TxOHIns[2]/
TxHDLCDat4[2]
G25
TxNib1[2]/
TxHDLCDat1[2]
G26
TxNib3[2]/
TxHDLCDat3[2]
TYPE
I
I
I
I
O
DESCRIPTION
See Description of Pin F3
Transmit Framer Reference Clock Input:
This input pin functions as the "Timing Reference" for the Transmit Section of
the XRT72L58 Framer, if the Framer has been configured to operate in the
"Local-Time" Mode. Further, if the XRT72L58 Framer has been configured to
operate in the "Local-Time" Mode, the "Transmit Payload Data Input Interface
will sample the data at the TxSer input pin, upon the rising edge of "TxInClk".
For E3 applications, the user should apply a 34.368MHz clock signal. For DS3
applications, the user should apply a 44.736MHz clock signal.
The user can configure the XRT72L58 Framer to operate in the "Local-Time"
mode by writing "xxxx xx01" or "xxxx xx1x" into the "Framer Operating Mode"
register (Address = 0x00)
Receiver LIU (Recovered) Clock:
This input signal serves three purposes:
1. The Receive Framer uses it to sample and "latch" the signals at the
RxPOS and RxNEG input pins (into the Receive Framer circuitry).
2. This input signal functions as the timing reference for the Receive Framer
block.
3. The Transmit Framer block can be configured to use this input signal as its
timing reference.
This signal is the recovered clock from the external DS3/E3 LIU (Line Inter-
face Unit) IC, which is derived from the incoming DS3/E3 data.
Receive Positive Data Input:
The exact role of this input pin depends upon whether the Framer is operating
in the Unipolar or Bipolar Mode.
Unipolar Mode:
This input pin functions as the "Single-Rail" input for the "incoming" E3 data
stream. The signal at this input pin will be sampled and latched (into the
Receive DS3/E3 Framer) on the "user-selected" edge of the RxLineClk signal.
Bipolar Mode:
This input functions as one of the dual rail inputs for the incoming AMI/HDB3
encoded DS3 or E3 data that has been received from an external Line Inter-
face Unit (LIU) IC. RxNEG functions as the other dual rail input for the Framer.
When this input pin is asserted, it means that the LIU has received a "positive
polarity" pulse from the line.
See Description of Pin A4
I
See Description of Pin A16
I
See Description of Pin B5
I
See Description of Pin A1
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