XRT72L50 Datasheet, PDF (29/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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PIN DESCRIPTION
PIN #
84
PIN NAME
RxNib1/
RxHDLCDat1
85
RxNib0/
RxHDLCDat0
86
RxSer/
RxIdle
87
RxAIS
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. 1.2.1
TYPE
O
O
O
O
DESCRIPTION
Receive Nibble Output - 1:
The Framer IC will output Received data (from the Remote Terminal) to the
local Terminal Equipment via this pin along with RxNib0, RxNib2 and RxNib3.
The data at this pin is updated on the rising edge of the RxClk output signal.
NOTE: This output pin is active only if the Nibble-Parallel Mode has been
selected.
Receive HDLC Data Output - 1:
This pin contains bit 1 RxHDLC data when the HDLC controller is on.
Receive Nibble Output - 0:
The Framer IC will output Received data (from the Remote Terminal) to the
local Terminal Equipment via this pin along with RxNib1, RxNib2 and RxNib3.
The data at this pin is updated on the rising edge of the RxClk output signal.
NOTE: This output pin is active only if the Nibble-Parallel Mode has been
selected.
Receive HDLC Data Output - 0:
This pin contains bit 0 RxHDLC data when the HDLC controller is on.
Receive Serial Output:
If the user opts to operate the XRT72L50 in the serial mode, then the chip will
output the payload data, of the incoming DS3 or E3 frames, via this pin. The
XRT72L50 will output this data upon the rising edge of RxClk.
The user is advised to design the Terminal Equipment such that it will sample
this data on the falling edge of RxClk.
NOTE: This signal is only active if the NibIntf input pin is pulled "Low".
Receive Idle:
This pin will go "High" indicating the idle period of sent HDLC data packets.
Also, in combination with ValFCS it can indicate error conditions.
Receive Alarm Indication Signal Output pin:
The Framer will assert this pin to indicate that the Alarm Indication Signal
(AIS) has been identified in the Receive DS3 or E3 data stream.
For DS3 Applications:
The Framer will assert this pin to indicate that the Alarm Indication Signal
(AIS) has been identified in the Receive DS3 data stream. An AIS is detected
if the payload consists of the recurring pattern of 1010... and this pattern per-
sists for 63 M-frames. An additional requirement for AIS indication is that the
C-bits are set to 0, and the X-bits are set to 1. This pin will be negated when a
sufficient number of frames, not exhibiting the 1010... pattern in the payload
has been detected.
For E3 Applications:
The Receive Section will declare an AIS condition, if it detects two consecu-
tive E3 frames, each containing 7 or less "0s".
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