XRT73L00A Datasheet, PDF (38/53 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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If the XRT73L00A is operating in the HOST Mode,
the state of ALOS can be polled or monitored by
reading in the contents of Command Register 0. The
bit-format of Command Register 0 is presented be-
low.
COMMAND REGISTER CR0 (ADDRESS = 0X00)
D4
D3
D2
D1
D0
RLOL
RLOS ALOS DLOS
DMO
Read
Only
Read
Only
Read
Only
Read
Only
Read
Only
If the ALOS bit-field contains a “1”, the XRT73L00A is
currently declaring an ALOS condition. If the ALOS
bit-field contains a “0”, the device is NOT currently de-
claring an ALOS condition.
Disabling the ALOS Detector
It is useful to disable the ALOS Detector in the
XRT73L00A for debugging purposes. If the
XRT73L00A is operating in the HOST Mode, the
ALOS Detector can be disabled by writing a “1” into
the ALOSDIS bit-field in Command Register 2 as de-
picted below.
COMMAND REGISTER CR2 (ADDRESS = 0X02)
D4
D3
D2
D1
D0
Reserved ENDECDIS ALOSDIS DLOSDIS REQDIS
X
X
1
X
X
NOTE: Setting both the ALOSDIS and DLOSDIS bit-fields
to “1” disables LOS Declaration in the XRT73L00A.
2. The Digital LOS (DLOS) Declaration/Clear-
ance Criteria
The XRT73L00A declare a Digital LOS (DLOS) con-
dition if the XRT73L00A detects 160±32 or more con-
secutive “0’s” in the incoming data.
The XRT73L00A clears DLOS if it detects four con-
secutive sets of 32 bit-periods each of which contains
at least 10 “1’s” (e.g., average pulse density of greater
than 33%).
Monitoring the State of DLOS
If the XRT73L00A is operating in the HOST Mode,
the state of DLOS can be polled or monitored by
reading in the contents of Command Register 0 as
shown.
COMMAND REGISTER CR0 (ADDRESS = 0X00)
D4
D3
D2
D1
D0
RLOL
RLOS
ALOS DLOS
DMO
Read
Only
Read
Only
Read
Only
Read
Only
Read
Only
If the DLOS bit-field contains a “1”, the XRT73L00A is
currently declaring a DLOS condition. If the DLOS
bit-field contains a “0”, the device is NOT currently de-
claring the DLOS condition.
Disabling the DLOS Detector
It is useful to disable the DLOS Detector in the
XRT73L00A for debugging purposes. If the
XRT73L00A is operating in the HOST Mode, the
DLOS Detector can be disabled by writing a “1” into
the DLOSDIS bit-field in Command Register 2.
COMMAND REGISTER CR2 (ADDRESS = 0X02)
D4
D3
D2
D1
D0
Reserved ENDECDIS ALOSDIS DLOSDIS REQDIS
X
X
X
1
X
NOTE: Setting both the ALOSDIS and DLOSDIS bit-fields
to a “1” disables LOS Declaration in the XRT73L00A.
3.6.3 Muting the Recovered Data while the LOS
is being Declared
In some applications it is not desirable for the
XRT73L00A E3/DS3/STS-1 LIU to recover data and
route it to the Receiving Terminal while the LIU is de-
claring a LOS condition. The LOS Muting feature, if
enabled, causes the XRT73L00A to halt transmission
of the recovered data to the Receiving Terminal while
the LOS condition is True. In this case, the RPOS
and RNEG output pins are forced to “0”. Once the
LOS condition has been cleared, the XRT73L00A re-
sumes the transmission of the recovered data to the
Receiving Terminal. The XRT73L00A allows en-
abling of the Muting Upon LOS feature by either of
the following means.
If the XRT73L00A is Operating in the Hardware
Mode:
The Muting Upon LOS feature is enabled by pulling
the LOSMUTEN input pin (pin 19) to VDD.
If the XRT73L00A is Operating in the HOST Mode:
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