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PRELIMINARY
XRT79L71
70
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
TABLE 13: LIST AND DESCRIPTION OF THE PINS ASSOCIATED WITH THE TRANSMIT PAYLOAD DATA INPUT INTERFACE
BLOCK
SIGNAL NAME
PIN/BALL #
TYPE
DESCRIPTION
TxSer
C9
I
Transmit Serial Payload Data Input Pin:
If the Transmit Payload Data Input Interface block is operated in the Serial Mode,
then the System-Side equipment is expected to apply the payload data that is to
be transported via the outbound DS3 data-stream to this input pin, in a serial
manner. The XRT79L71 samples the data that is on this input pin upon the rising
edge of either the RxOutClk for loop-timing applications or the TxInClk signal or
local-timing applications.
NOTE: This signal is only active if the NibIntf input pin is pulled "Low".
TxNib[3:0]
B8
C8
D8
A9
I
Transmit Nibble-Parallel Payload Data Input pins:
If the Transmit Payload Data Input Interface block is operated in the Nibble-Par-
allel Mode, then the System-Side equipment is expected to apply the payload
data that is to be transported via the outbound DS3 data-stream to these input
pins, in a nibble-parallel manner. The XRT79L71 samples the data that is placed
on these input pins upon the third rising edge of TxInClk, following a given rising
edge of the TxNibClk output pin.
NOTE: These signals are only active if the NibIntf input pin is pulled "High".
TxNibFrame
A10
O
Transmit End of Frame Output Indicator - Nibble Mode:
The Transmit Section of the XRT79L71 pulses this output pin "High" for one nib-
ble period whenever the Transmit Payload Data Input Interface block is process-
ing the very last nibble within a given DS3 frame. The purpose of this output pin
is to alert the System-Side Terminal Equipment that it needs to begin transmis-
sion of a new DS3 frame to the Transmit Payload Data Input Interface of the
XRT79L71.
NOTE: This output pin is only active if the XRT79L71 has been configured to
operate in the Nibble-Parallel Mode
TxInClk
C10
I
Transmit Section - Timing Reference Clock Input pin:
If the XRT79L71 has been configured to operate in the Local-Timing Mode, then
this input pin will function as the timing source for the Transmit Circuitry within the
XRT79L71.
Additionally, if the XRT79L71 has been configured to operate in both the Serial
and Local-Timing Mode, then the XRT79L71 will sample the data, residing on the
TxSer input pin, upon the rising edge of this input clock signal.
TxNibClk
D9
O
Transmit Nibble-Mode Clock Output SignalIf the XRT79L71 has been configured
to operate in the Nibble-Parallel Mode, then the XRT79L71 will derive this output
clock signal from either the TxInClk or the LIU Recovered Clock signal.
NOTE: The frequency of this clock output signal is approximately one-fourth of
the TxInClk or the RxOutClk signals.
The user is advised to update the Nibble-Parallel data via the TxNib[3:0] output
pins, upon the rising edge of this clock output signal. The XRT79L71 will sample
the TxNib[3:0] input pins upon the third rising edge of the TxInClk clock input sig-
nal following a rising edge in this particular signal.