XRT73LC00A Datasheet, PDF (40/53 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73LC00A
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. P1.0.0
xr
PRELIMINARY
FIGURE 25. HOW THE XRT73LC00A OUTPUTS DATA ON THE RPOS AND RNEG OUTPUT PINS
RPOS
RNEG
RCLK1
RCLK1 (or RCLK2) is the Recovered Clock signal
from the incoming Received line signal. These clock
signals are typically 34.368 MHz for E3 applications,
44.736 MHz for DS3 applications and 51.84 MHz for
SONET STS-1 applications.
If the XRT73LC00A received a positive-polarity pulse
in the incoming line signal via the RTIP and RRING
input pins, then the XRT73LC00A pulses the RPOS
output pin “High”. If the XRT73LC00A received a
negative-polarity pulse in the incoming line signal via
the RTIP and RRING input pins, then the
XRT73LC00A pulses the RNEG output pin “High”.
Inverting the RCLK1 or RCLK2 outputs
When using the XRT73LC00A, either of the RCLK1
or RCLK2 signals can be inverted with respect to the
delivery of the RPOS and RNEG output signals to the
Receiving Terminal Equipment. This feature may be
useful for those customers whose Receiving Terminal
Equipment logic design is such that the RPOS and
RNEG data must be sampled on the rising edge of
RCLK1 or RCLK2. Figure 26 illustrates the behavior
of the RPOS, RNEG and RCLK signals when the
RCLK signal has been inverted.
FIGURE 26. THE BEHAVIOR OF THE RPOS, RNEG AND RCLK1 SIGNALS WHEN RCLK1 IS INVERTED
RPOS
RNEG
RCLK1
To configure the XRT73LC00A to invert the RCLK1
output signal, the XRT73LC00A must be operating in
the HOST Mode. This configuration can be imple-
mented by accessing the Microprocessor Serial Inter-
face block and writing a “1” into the RCLK1INV bit-
field in Command Register CR3 to invert RCLK1.
COMMAND REGISTER CR3 (ADDRESS = 0X03)
D4
D3
D2
D1
D0
RNRZ LOSMUT CLK2DIS RCLK2INV RCLK1INV
X
X
X
1
1
The RCLK2 output signal can also be inverted when
the XRT73LC00A is operating in the Hardware Mode
by setting the RCLK2INV input pin “High”.
3.7.1 Routing Single-Rail Format data (Binary
Data Stream) to the Receive Terminal Equipment
To route Single-Rail format data (e.g., a binary data
stream) from the Receive Section of the
XRT73LC00A to the Receiving Terminal Equipment,
do the following:
A. configure the XRT73LC00A to operate in the
HOST Mode and
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