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XRT79L71
PRELIMINARY
269
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
TxOHInd/
TxGapClk
B9
O
Transmit Overhead Bit Indicator Output/Transmit Gap-Clock Output:
The exact function of this output pin depends upon whether the XRT79L71 has been
configured to operate in the Gapped-Clock Mode or Not.
Non-Gapped Clock Mode - TxOHInd:
This output pin will pulse "High" one bit period prior to the time that the Transmit Sec-
tion of the XRT79L71 is processing an Overhead bit. This output pin will be held
"Low" at all other times. The purpose of this output pin is to warn the System-Side
Terminal Equipment that during the very next bit-period, the XRT79L71 is going to be
processing an Overhead bits and will be, during this very next bit-period, ignoring any
data that is applied to the TxSer input pin.
Gapped-Clock Mode - TxGapClk:
If the XRT79L71 has been configured to operate in the Gapped-Clock Mode, then this
particular output pin will function as a demand output clock signal. In this case, the
System-Side Terminal Equipment will be expected to update the data on the TxSer
input pin, upon the rising edge of this particular output signal. The XRT79L71 will
sample and latch the TxSer data, upon the falling edge of the TxGapClk signal.
NOTE: In the Gapped-Clock Mode, the XRT79L71 will only generate a clock edge via
this output pin whenever the Transmit Payload Data Input Interface is
processing payload data. The XRT79L71 will NOT generate a clock edge via
this output pin whenever the Transmit Payload Data Input Interface is
processing an overhead bit.
TxFrame
B10
O
Transmit End of Frame Output Indicator:
The Transmit Section of the XRT79L71 pulses this output pin "High" for one bit-period
coincident to whenever the Transmit Payload Data Input Interface block is processing
the last bit of a given E3 frame.
The purpose of this output pin is to alert the System-Side Terminal Equipment that it
needs to begin transmission of a new E3 frame to the Transmit Payload Data Input
Interface block of the XRT79L71 (e.g., to permit the XRT79L71 to maintain Transmit
E3 Framing alignment control over the System-Side Terminal Equipment).
TABLE 36: LIST AND DESCRIPTION OF THE PINS ASSOCIATED WITH THE TRANSMIT PAYLOAD DATA INPUT INTERFACE
BLOCK
SIGNAL NAME
PIN/
BALL #
TYPE
DESCRIPTION