XRT7300
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 1.1.1
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PIN DESCRIPTION
P
IN
#
11
S
YMBOL
REGRESET/
T
YPE
I
D
ESCRIPTION
Register Reset Input pin (Invert RCLK2 Output - Select):
The function of this pin depends upon whether the XRT7300 is operating in the
HOST Mode or in the Hardware Mode.
HOST Mode - Register Reset Input pin:
Setting this input pin “Low” causes the XRT7300 to reset the contents of the
Command Registers to their default settings and operating configuration. This
pin is internally pulled “High”.
Hardware Mode - Invert RCLK2 Output Select:
Setting this input pin “Low” configures the Receive Section of the XRT7300 to
output the recovered data via the RPOS and RNEG output pins on the rising
edge of the RCLK2 output signal.
Setting this input pin “High” configures the Receive Section to output the recov-
ered data on the falling edge of the RCLK2 output signal.
Receive Equalization Disable Input:
Setting this input pin “High” disables the Internal Receive Equalizer in the
XRT7300. Setting this pin “Low” enables the Internal Receive Equalizer. The
guidelines for enabling and disabling the Receive Equalizer are described in
N
OTES
:
1. This input pin is ignored if the XRT7300 is operating in the HOST Mode.
2. Tie this pin to GND if the XRT7300 is going to be operating in the HOST
Mode.
Loss of Signal Threshold Control:
The voltage forced on this pin controls the input loss of signal (LOS) threshold.
Two settings are provided by forcing this signal to either GND or VDD.
N
OTE
:
This pin is only applicable during DS3 or STS-1 operations.
Local Loop-Back Select:
This input pin along with RLB dictates which Loop-Back mode the XRT7300 is
operating in.
A “High” on this pin with RLB being set to “Low” configures the XRT7300 to oper-
ate in the Analog Local Loop-Back Mode.
A “High” on this pin with RLB also being set to “High” configures the XRT7300 to
operate in the Digital Local Loop-Back Mode.
N
OTES
:
1. This input pin is ignored if the XRT7300 is operating in the HOST Mode.
2. Tie this pin to GND if the XRT7300 is going to be operating in the HOST
Mode.
Remote Loop-Back Select:
This input pin along with LLB dictates which Loop-Back mode the XRT7300 is be
operating in.
A “High” on this pin with LLB being set to “Low” configures the XRT7300 to oper-
ate in the Remote Loop-Back Mode.
A “High” on this pin with LLB also being set to “High” configures the XRT7300 to
operate in the Digital Local Loop-Back Mode.
N
OTES
:
1. This input pin is ignored if the XRT7300 is operating in the HOST Mode.
2. Tie this pin to GND if the XRT7300 is going to be operating in the HOST
Mode.
(RCLK2INV)
12
REQDIS
I
13
LOSTHR
I
14
LLB
I
15
RLB
I
4
EXAR [ EXAR CORPORATION ]
