XRT79L74 Datasheet, PDF (34/70 Pages) Exar Corporation – 4 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

XRT79L74
REV. P1.0.0
PIN #
N2
J25
R5
L26
NAME
RxPFrame1/
RxOHInd1
RxPFrame2/
RxOHInd2
RxPFrame3/
RxOHInd3
RxPFrame4/
RxOHInd4
PRELIMINARY
4 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
TYPE
O
O
O
O
DESCRIPTION
Receive PLCP Frame Indicator/Receive Overhead Indicator Output:
The function of these output pins depend upon whether the XRT79L74 has
been configured to operate in the ATM/PLCP, the Clear-Channel Framer/Serial
or the Clear-Channel Framer/Nibble-Parallel Modes.
ATM/PLCP Mode - RxPFrame:
These output pins pulse "High" when the Receive PLCP Processor is receiving
the last bit of a PLCP frame.
NOTE: These output pins are inactive if the XRT79L74 is configured to operate
in the Direct-Mapped ATM Mode.
Clear-Channel Framer/Serial Mode - RxOHInd:
These output pins pulse "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.
NOTE:
If the user configures the XRT79L74 to operate in the Gapped-Clock
Mode, then these output pins will provide a demand clock to the local
terminal equipment. In the Gapped-Clock Mode, these output pins will
only provide a clock pulse, whenever a payload bit is being output via
the RxSer output pin. These output pins will NOT generate a clock
pulse, whenever an overhead is being output via the RxSer output pin.
Clear-Channel Framer/Nibble-Parallel - RxOHInd:
These output pins pulse "High" for one nibble-period whenever an overhead
nibble is being output via the RxNibn[3:0] output pins by the Receive Payload
Data Output Interface block.
NOTE: 1.If the XRT79L74 device has been configured to operate in both the
DS3 and the Nibble-Parallel" Modes, then the RxOHInd output pin will
be in-active and will pulled "LOW" at all times.
NOTE: 2.If the XRT79L74 device has been configured to operate in both the E3
and the Nibble-Parallel" Mode, then the RxOHInd output pin will be
active and will pulse "high" to denote overhead nibbles.
NOTE: 3.The purpose of this output pin is to alert the System-Side terminal
equipment that an
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