XRT75R03D_06 Datasheet, PDF (124/135 Pages) Exar Corporation – EXAR DATA SHEET FORMAT TEMPLATES

XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER REV. 1.0.4
10.7.2 Wander Measurement Test Results
Wander Measurement test results will be provided in the next revision of the XRT75R03D Data Sheet.
10.8 Designing with the XRT75R03D
In this section, we will discuss the following topics.
• How to design with and configure the XRT75R03D to permit a system to meet the above-mentioned Intrinsic
Jitter and Wander requirements.
• How is the XRT75R03D able to meet the above-mentioned requirements?
• How does the XRT75R03D permits the user to comply with the SONET APS Recovery Time requirements of
50ms (per Telcordia GR-253-CORE)?
• How should one configure the XRT75R03D, if one needs to support "Daisy-Chain" Testing at the end
Customer's site?
10.8.1 How to design and configure the XRT75R03D to permit a system to meet the above-
mentioned Intrinsic Jitter and Wander requirements
As mentioned earlier, in most application (in which the XRT75R03D will be used in a SONET De-Sync
Application) the user will typically interface the XRT75R03D to a Mapper device in the manner as presented
below in Figure 58.
In this application, the Mapper has the responsibility of receiving a SONET STS-N/OC-N signal and extracting
as many as N DS3 signals from this signal. As a given channel within the Mapper IC extracts out a given DS3
signal (from SONET) it will typically be applying a Clock and Data signal to the "Transmit Input" of the LIU IC.
Figure 58 presents a simple illustration as to how one channel, within the XRT75R03D should be connected to
the Mapper IC.
FIGURE 58. ILLUSTRATION OF THE XRT75R03D BEING CONNECTED TO A MAPPER IC FOR SONET DE-SYNC
APPLICATIONS
STS-N Signal
De-Mapped (Gapped)
DS3 Data and Clock
DDSS33totoSSTTSS-N-N
MMaappppeerr//
DDeemmaappppeerr
IICC
TPDATA_n input pin
XXRRTT7755RR0033DD
TCLK_n input
As mentioned above, the Mapper IC will typically output a Clock and Data signal to the XRT75R03D. In many
cases, the Mapper IC will output the contents of an entire STS-1 data-stream via the Data Signal to the
XRT75R03D. However, the Mapper IC typically only supplies a clock pulse via the Clock Signal to the
XRT75R03D coincident to whenever a DS3 bit is being output via the Data Signal. In this case, the Mapper IC
would not supply a clock edge coincident to when a TOH, POH or any non-DS3 data-bit is being output via the
Data-Signal.
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