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XRT75R06D Datasheet, PDF (44/105 Pages) Exar Corporation – SIX CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER | |||
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XRT75R06D
áç
REV. 1.0.0
SIX CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
6.0 DIAGNOSTIC FEATURES
6.1 PRBS Generator and Detector
The XRT75R06D contains an on-chip Pseudo Random Binary Sequence (PRBS) generator and detector for
diagnostic purpose. With the PRBSEN_n bit = â1â, the transmitter will send out PRBS of 223-1 in E3 rate or
215-1 in STS-1/DS3 rate. At the same time, the receiver PRBS detector is also enabled. When the correct
PRBS pattern is detected by the receiver, the RNEG/LCV pin will go âLowâ to indicate PRBS synchronization
has been achieved. When the PRBS detector is not in sync the PRBSLS bit will be set to â1â and RNEG/LCV
pin will go âHighâ.
With the PRBS mode enabled, the user can also insert a single bit error by toggling âINSPRBSâ bit. This is
done by writing a â1â to INSPRBS bit. The receiver at RNEG/LCV pin will pulse âHighâ for one RxClk cycle for
every bit error detected. Any subsequent single bit error insertion must be done by first writing a â0â to
INSPRBS bit and followed by a â1â.
Figure 30 shows the status of RNEG/LCV pin when the XRT75R06D is configured in PRBS mode.
NOTE: In PRBS mode, the device is forced to operate in Single-Rail Mode.
FIGURE 30. PRBS MODE
RxClk
SYNC LOSS
RxNEG/LCV
PRBS SYNC
Single Bit Error
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