Software Description
15
SNLU238A – August 2018 – Revised September 2019
Copyright © 2018–2019, Texas Instruments Incorporated
DS250DF230EVM User’s Guide
Figure 14. Cross-Point Tab, Lane Crossing Mode Selected
2.2.4.5
CDR (Clock and Data Recovery)
The CDR tab provides a quick way to configure the DS250DF230 retimer to operate at the desired data
rates and sub-rates. The DS250DF230 channels must each be pre-programmed for the expected data
rate(s) to ensure CDR lock. On the CDR tab the user can select between the Standard and Manual
modes of CDR lock configuration.
•
Upon landing on the CDR tab, the page will automatically display the mode that the retimer is currently
set to, along with the data rate setting and also the divider setting (in the case of Manual Mode.)
•
Standard Mode allows the user to program the retimer rate/sub-rate to one of within a set of pre-
defined standard values.
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Select the desired channel on Channel Select pull-down.
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The user first clicks on the “Standard Mode” option on the page.
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The user then selects the desired rate within the “Standard Data Rate Selection” Options.
NOTE:
The default settings for the DS250DF230 are “Standard Mode”, and “100Gb Ethernet”
(i.e 25.78125 Gb/s data rate per channel).
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Manual Mode allows the user to manually program a retimer channel to CDR lock to a specific data
rate. This function is intended for applications requiring a data rate that exists within the VCO range,
but that are not listed within the “Standard Data Rate Selection” options.