XR72L52 Datasheet, PDF (29/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
XRT72L52
REV. 1.0.1
PIN DESCRIPTION
PIN #
121
122
123
124
125
PIN NAME
RxNib0[0]/
RxHDLCDat0[0]
RxFrame[0]
VDD
RxOHInd[0]
RxSer[0]/
RxIdle[0]
TYPE
O
DESCRIPTION
Receive Nibble Output - 0:
The Framer IC outputs Received data from the Remote Terminal to the local Ter-
minal 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.
O Receive Boundary of DS3 or E3 Frame Output Indicator:
The function of this output pin depends upon whether the XRT72L52 Framer is
operating in the Serial or Nibble-Parallel Mode.
Serial Mode Operation:
The Receive Section of the XRT72L52 pulses this output pin "High" for one bit-
period, when the Receive Payload Data Output Interface block is driving the
very first bit of a given DS3 or E3 frame onto the RxSer output pin.
Nibble-Parallel Operation:
The Receive Section of the XRT72L52 pulses this output pin "High" for one nib-
ble-period, when the Receive Payload Data Output Interface block is driving the
very first nibble of a given DS3 or E3 frame onto the RxNib[3:0] output pins.
**** Power Supply 3.3V + 5%
O _{Receive Overhead Bit Indicator:}
The function of this output pin depends upon whether the XRT72L52 Framer is
operating in the Serial or Nibble-Parallel Mode.
Serial Mode Operation:
This output pin pulses "High" for one bit-period whenever an overhead bit is
being output via the RxSer output pin, by the Receive Payload Data Output
Interface block.
Nibble-Parallel Mode Operation:
This output pin pulses "High" for one nibble-period whenever an overhead nib-
ble is being output via the RxNib[3:0] output pins, by the Receive Payload Data
Output Interface block.
NOTE: The purpose of this output pin is to alert the Receive Terminal Equipment
that an overhead bit is being output via the RxSer output pin, and that this data
should be ignored.
O Receive Serial Output:
If the user operates the XRT72L52 in the serial mode, then the chip outputs the
payload data of the incoming DS3 or E3 frames via this pin. The XRT72L52 out-
puts this data upon the rising edge of RxClk.
The user is advised to design the Terminal Equipment such that it samples this
data on the falling edge of RxClk.
NOTE: This signal is only active if the NibInt input pin is pulled "Low".
Receive Idle:
This pin goes "High" to indicate the idle period of sent HDLC data packets. Also,
in combination with ValFCS it can indicate error conditions.
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