XRT72L52 Datasheet, PDF (22/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L52
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.3
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PRELIMINARY
PIN DESCRIPTIONS
PIN DESCRIPTION
PIN #
1
2
PIN NAME
VDD
RxOOF[0]
3
RxLOS[0]
4
EncoDis[0]
TYPE
****
O
O
O
DESCRIPTION
Power Supply 3.3V + 5%
Receiver "Out of Frame" Indicator:
The Receive Section of the XRT72L52 Framer IC will assert this output
signal whenever it has declared an "Out of Frame" (OOF) condition with
the incoming DS3 or E3 frames. This signal is negated when the framer
correctly locates the framing alignment bits or bytes and correctly aligns
itself with the incoming DS3 or E3 frames.
Receive Section - Loss of Signal Output Indicator:
This pin is asserted when the Receive Section encounters a string of
180 consecutive 0's (for DS3 operation) or 32 consecutive 0's (for E3
operation) via the RxPOS and RxNEG pins.
This pin will be negated once the Receive Section has detected at least
60 pulses within 180 bit-periods (for DS3 operation); or the Receive
Section has detected a string of 32 consecutive bits, that does not con-
tain a string of 4 consecutive "0s" (for E3 operation).
Encoder (HDB3) Disable Output pin (intended to be connected to
the XRT7300 DS3/E3 Line Interface Unit IC):
This output pin is intended to be connected to the Encodis input pin of
the XRT7300 DS3/E3 Line Interface Unit IC. The user can control the
state of this output pin by writing a "0" or "1" to Bit 3 (Encodis) within the
Line Interface Driver Register (Address = 0x80). If the user commands
this signal to toggle "high" then it will disable the B3ZS/HDB3 encoder
circuitry within the XRT7300 IC. Conversely, if the user commands this
output signal to toggle "low", then the B3ZS/HDB3 Encoder circuitry,
within the XRT7300 IC will be enabled.
Writing a "1" to Bit 3 of the Line Interface Driver Register (Address =
0x80) will cause this output pin to toggle "high". Writing a "0" to this bit-
field will cause this output pin to toggle "low".
The user is advised to disable the B3ZS/HDB3 encoder (within the
XRT7300 IC) if the XRT72L52 Framer IC has been configured to oper-
ate in the B3ZS/HDB3 line code.
If the customer is not using the XRT7300 DS3/E3 Line Interface Unit IC,
then he/she can use this output pin for a variety of other purposes.
3