XRT75L00IV View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XRT75L00IV' PDF : 50 Pages View PDF
REV. 1.0.2
XRT75L00
E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
In order to configure the device for internal transmit driver monitoring, set the TxMON bit to “1” in the transmit
control register.
FIGURE 16. TRANSMIT DRIVER MONITOR SET-UP.
TxPO S
TxN E G
T x L in e C lk
TxPO S
TxN EG
T x L in e C lk
T T IP
T P D a ta
T N D a ta
T x C lk
R ext
R e fA G N D
T R in g
M T IP
M R in g
XRT75L00
T P D a ta
T N D a ta
T x C lk
M T IP
M R in g
T T IP
3 7 .4 Ω + 1 %
3 7 .4 Ω + 1 %
R4 270Ω
R5 270Ω
3 7 .4 Ω + 1 %
R ext
R e fA G N D
T R in g
3 7 .4 Ω + 1 %
R3
75Ω
1 :1
1 :1
R3
75Ω
When the MTIP and MRing are connected to the TTIP and TRing lines, the drive monitor circuit monitors the
line for transitions. The DMO (Drive Monitor Output) will be asserted “Low” as long as the transitions on the line
are detected via MTIP and MRing.
If no transitions on the line are detected for 128 ± 32 TxClk periods, the DMO output toggles “High” and when
the transitions are detected again, DMO toggles “Low”.
NOTE: The Drive Monitor Circuit is only for diagnostic purposes and does not have to be used to operate the transmitter.
4.5 Transmitter Section On/Off:
The transmitter section can be turned on or off. To turn on the transmitter in the Hardware mode, pull TxON pin
“High”. In the Host mode, write a “1” to the TxON control bit AND pull the TxON pin “High” to turn on the
transmitter.
When the transmitter is turned off, the TTIP and TRing are tri-stated.
NOTES:
1. This feature provides support for Redundancy.
2. If the XRT75L00 is configured in Host mode, to permit a system designed for redundancy to quickly shut-off the
defective line card and turn on the back-up line card, writing a “1” to the TxON control bit transfers the control to
TxON pin.
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