XRT79L74 Datasheet, PDF (32/70 Pages) Exar Corporation – 4 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

XRT79L74
REV. P1.0.0
PIN #
N1
J24
P1
L25
NAME
RxPOH1/
RxSer1
RxPOH2/
RxSer2
RxPOH3/
RxSer3
RxPOH4/
RxSer4
PRELIMINARY
4 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
TYPE
O
O
O
O
DESCRIPTION
Receive PLCP Path Overhead Output pin/Receive Serial Output pin:
The function of these outputs depend upon whether the XRT79L74 has been
configured to operate in the ATM/PLCP Mode or in the Clear-Channel Framer
Mode.
ATM/PLCP Mode - RxPOH:
These output pins along with the RxPOHClk, RxPOHFrame and RxPOHIns
pins comprise the Receive PLCP Frame POH Byte serial output port. For each
PLCP frame, that is received by the Receive PLCP Processor, this serial output
port will output the contents of all 12 POH (Path Overhead) bytes. The data that
is output via these pins are updated on the rising edge of the RxPOHClk output
clock signals. The RxPOHFrame pin will pulse "High" whenever the first bit of
the Z6 byte is being output via these output pins.
Clear-Channel Framer Mode - RxSer:
If the XRT79L74 is configured to operate in the Clear-Channel Framer/Serial
Mode, then the chip will output all received data, via these output pins. These
output signals will be updated upon the rising edge of RxClk.
NOTE:
The user should either configure the XRT79L74 to operate in the
Gapped-Clock Mode, or validate the sampling of each bit from the
RxSer output with the state of RxOHInd’ output pin, in order to prevent
the local terminal equipment from sampling overhead bits.
These output pins are only active if the XRT79L74 has been configured to oper-
ate in the ATM/PLCP or the Clear-Channel Framer/Serial Mode. These pins
are inactive for all remaining modes of operation.
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