XRT73L00A Datasheet, PDF (8/53 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73L00A
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 2.0.1
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PIN DESCRIPTION
PIN #
15
16
17
18
SYMBOL
RLB
STS-1/DS3
E3
HOST/HW
TYPE
I
I
I
I
DESCRIPTION
Remote Loop-Back Select:
This input pin along with LLB dictates which Loop-Back mode the XRT73L00A is
operating in.
A “High” on this pin with LLB being set to “Low” configures the XRT73L00A to
operate in the Remote Loop-Back Mode.
A “High” on this pin with LLB also being set to “High” configures the XRT73L00A
to operate in the Digital Local Loop-Back Mode.
NOTES:
1. This input pin is ignored if the XRT73L00A is operating in the HOST
Mode.
2. Tie this pin to GND if the XRT73L00A is going to be operating in the
HOST Mode.
STS-1/DS3 Select Input:
A “High” on this pin configures the Clock Recovery Phase Locked Loop to set its
VCO Center frequency to around 51.84 MHz for SONET STS-1 operations. A
“Low” on this pin configures the Clock Recovery Phase Locked Loop to set its
VCO Center frequency to around 44.736 MHz for DS3 operations.
NOTES:
1. The XRT73L00A ignores this pin if the E3 pin (pin 17) is set to “1”.
2. This input pin is ignored if the XRT73L00A is operating in the HOST
Mode.
3. Tie this pin to GND if the XRT73L00A is going to be operating in the
HOST Mode.
E3 Select Input:
A “High” on this pin configures the XRT73L00A to operate in the E3 Mode.
A “Low” on this pin configures the XRT73L00A to check the state of the STS-1/
DS3 input pin.
NOTES:
1. This input pin is ignored if the XRT73L00A is operating in the HOST
Mode.
2. Tie this pin to GND if the XRT73L00A is going to be operating in the
HOST Mode.
HOST/HW Mode Select:
This input pin is used to enable or disable the Microprocessor Serial Interface
(e.g., consisting of the SDI, SDO, SCLK, CS and REGRESET pins).
Setting this input pin “High” enables the Microprocessor Serial Interface (e.g.
configures the XRT73L00A to operate in the HOST Mode). In this mode, the
XRT73L00A is configured by writing data into the on-chip Command Registers
via the Microprocessor Serial Interface. When the XRT73L00A is operating in
the HOST Mode, it ignores the states of many of the discrete input pins.
Setting this input pin “Low” disables the Microprocessor Serial Interface (e.g.,
configures the XRT73L00A to operate in the Hardware Mode). In this mode,
many of the external input control pins are functional.
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