Texas Instruments DS250DF810EVM User manual

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DS250DF810EVM User’s Guide
User's Guide
SNLU180C–August 2015–Revised September 2019
DS250DF810EVM User’s Guide
The DS250DF810 is an eight-channel multi-rate retimer with integrated signal conditioning. It is used to
extend the reach and robustness of long, lossy, crosstalk-impaired high-speed serial links while achieving
a bit error rate (BER) of 10-15 or less. Each channel of the DS250DF810 independently locks to serial
data rates in a continuous range from 20.6 Gbps to 25.8 Gbps or to any supported sub-rate (÷2 and ÷4),
including key data rates such as 10.3125 Gbps and 12.5 Gbps. Integrated physical AC coupling
capacitors (TX and RX) eliminate the need for external capacitors on the PCB. The DS250DF810 has a
single power supply and minimal need for external components. These features reduce PCB routing
complexity and BOM cost. The advanced equalization features of the DS250DF810 include a low-jitter 3-
tap transmit finite impulse response (FIR) filter, an adaptive continuous-time linear equalizer (CTLE), and
an adaptive decision feedback equalizer (DFE). This enables reach extension for lossy interconnect and
backplanes with multiple connectors and crosstalk. The integrated CDR function is ideal for front-port
optical module applications to reset the jitter budget and retime the high-speed serial data. The
DS250DF810 implements 2x2 cross-point on each channel pair, providing the host with both lane crossing
and fanout options.
The DS250DF810 can be configured via the default SMBus slave mode or with an external EEPROM. Up
to 16 devices can share a single EEPROM. A non-disruptive on-chip eye monitor and PRBS generator
and checker functions allow for in-system diagnostics. With this kit, users can quickly evaluate the
DS250DF810 retimer performance.

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DS250DF810EVM User’s Guide
Contents
1 Hardware Description and Setup .......................................................................................... 3
2 Software Description ........................................................................................................ 4
3 Best Practices and Usage Tips........................................................................................... 21
4 Test Case Examples....................................................................................................... 22
5 Supplemental Documents................................................................................................. 23
6 EVM Cable Assemblies ................................................................................................... 24
List of Figures
1 DS250DF810EVM, Showing Necessary Connections for Power, Signal, and USB Communications........... 3
2 Download SigCon Architect from www.ti.com ........................................................................... 4
3 Sigcon Architect Start-Up Screen ......................................................................................... 5
4 Capture Illustrating the “Manage Devices” Pop-Up Window for Adding New Part Numbers to the
“Selection” Panel............................................................................................................. 6
5 Low-Level Page Capture Illustrating the Different Block Select Options............................................. 7
6 Low-Level Page Capture After Selecting Access to an Individual Register.......................................... 7
7 Eye Monitor Page for DS250DF810 Profile.............................................................................. 8
8 EEPROM Page for DS250DF810 Profile................................................................................. 9
9 High-Level Page, with Block Diagram Tab Selected .................................................................. 10
10 High-Level Page, with Device Status Tab Selected................................................................... 11
11 Rx EQ/DFE Tab............................................................................................................ 12
12 Cross-Point Tab, Default Mode Selected ............................................................................... 14
13 Cross-Point Tab, Fanout Mode Selected ............................................................................... 14
14 Cross-Point Tab, Lane Crossing Mode Selected ...................................................................... 15
15 CDR Tab, Standard Mode Selected..................................................................................... 16
16 CDR Tab, Manual Mode Selected....................................................................................... 17
17 TX FIR Tab.................................................................................................................. 18
18 PRBS Tab, PRBS Generator Configuration ............................................................................ 19
19 PRBS Tab, PRBS Checker Configuration .............................................................................. 20
20 SDD21 Loss Characteristic of Example Test Case.................................................................... 22
Trademarks
All trademarks are the property of their respective owners.

= Jumpers
Connect GND here
Connect 3.3 V here
Plug USB here
RX Channels
TX Channels
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DS250DF810EVM User’s Guide
1 Hardware Description and Setup
The general procedure for setting up and testing with the DS250DF810 Evaluation Module
(DS250DF810EVM) hardware is as follows:
1. Check the EVM jumper settings to ensure they match Figure 1 below.
2. Connect the EVM to a PC using the provided USB cable.
3. Connect 3.3V power (2A max) as shown below. The EVM has an on-board 3.3V-to-2.5V regulator to
supply the Retimer with the required 2.5V.
Figure 1. DS250DF810EVM, Showing Necessary Connections for Power, Signal, and USB
Communications
4. Connect the EVM to the system under test.
The default EVM configuration has four differential RX inputs and four differential TX outputs accessible to
the user. Connect the RX and TX signals to the test channel using Huber+Suhner 1x8 MXP cable
assemblies (See Section 6 for ordering information).
NOTE: All TX and RX channels are AC coupled with physical 220 nF capacitors on the package of
the device, so external AC coupling capacitors are not needed when using this EVM.

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2 Software Description
2.1 Setup
The one-time procedure for installing the GUI software is as follows:
1. Download and install the TI SigCon Architect GUI. The steps for installing the software are as follows:
1. Go to www.ti.com/tool/sigconarchitect and download the latest version of SigCon Architect. At the
time this document was written, the latest version of SigCon Architect is 2.0.0.4.
Figure 2. Download SigCon Architect from www.ti.com
2. Extract the executable file (.EXE) from the downloaded file and run the executable.
3. Follow the installation wizard’s instructions to install SigCon Architect.
4. Download the DS250DF810 profile file from the TI SigCon Architect page.
5. Extract the executable file (.EXE) from the downloaded file and run the executable.

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2. Run the SigCon Architect software.
1. Start the software by double-clicking its icon on the desktop.
2. On the “Selection” panel, the DS250DF810 should appear.
3. If DS250DF810 is not listed:
1. Go to “Device” tab and choose “Manage Devices”.
2. Click on “+” icon and then select the “DS250DF810” device model.
3. Fill in the “New Device Name, DS250DF810 is recommended.
4. Select the slave address as configured on EVM (typical setting is 0x30).
5. Click “OK”.
4. Navigate to the “Configuration” page of DS250DF810 via the “Selection” panel. Choose “Slave
Address” “0x30” from the drop down menu. Verify the “USB2ANY Details” specify “USB2ANY 0”,
and click “Apply”. Successful connection is indicated by the green “CONNECTED” indicator on the
bottom of the application.
Figure 3. Sigcon Architect Start-Up Screen

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Figure 4. Capture Illustrating the “Manage Devices” Pop-Up Window for Adding New Part Numbers to the
“Selection” Panel
3. Once connection is successfully established, users can read and write various settings to the device in
real-time, using the functional pages.
2.2 Functional Pages
2.2.1 Low-Level Page
The low-level page allows the user to read and write to all registers on the DS250DF810. To access it,
navigate to the “Low Level Page”, as shown below.
• The user may click “Read All” to load the data in each register from the device to the “Register Map."
• The user may access the Shared, Global or Channel registers via “Block Select.”
• To Read a register:
– Type the readable address in the “Current Address” text box or select a register from the Register
Map.
– Click “Read Register”. The data in this register will appear in the “Data” text box.
• To Write a register:
– Type the writeable address in the “Current Address” text box or select a register from the Register
Map.
– The user may either type the data value (in HEX) to write to this address in the “Data” text box, or
check/uncheck boxes as desired for individual bits within the register. Then click “Write Register.”
– If Broadcast is selected for channel register writes, the specified write will be performed to all
channels in the device.

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Figure 5. Low-Level Page Capture Illustrating the Different Block Select Options
Figure 6. Low-Level Page Capture After Selecting Access to an Individual Register

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2.2.2 Eye Opening Monitor (EOM) Page
The Eye monitor page allows the user to visualize DS250DF810 eye plots, a means of assessing received
signal quality after equalization.
• Select the channel for eye plotting. Note that plots can only be generated for a given channel if “CDR
Locked” is indicated.
• The EOM_SEL_VRANGE pull-down allows the user to adjust the vertical scale for eye plots.
• The user may perform a “Single Capture” of eye monitor plot, or select “Continuous Capture” to
accumulate multiple plots over a period of time.
• The Horizontal Eye Opening (HEO) and Vertical Eye Opening (VEO) may be read on the Eye Monitor
page.
• If the user desires to do their own analysis or post-processing of the EOM data, the “Export Raw Data”
and “Export Density” buttons respectively generate an Excel spreadsheet containing the 63x63 eye
monitor values matrix.
Figure 7. Eye Monitor Page for DS250DF810 Profile

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2.2.3 EEPROM Page
The SigCon Architect EEPROM page allows the user to either: create a DS250DF810 Hex file that is
programmable to an EEPROM, or configure a DS250DF810 device based on values from an existing
DS250DF810 Hex file.
Figure 8. EEPROM Page for DS250DF810 Profile
The user may choose to update the EEPROM page settings based on values read from the DS250DF810
device by clicking “Update Slot from Device”. To create the programmable hex file, click “Write to
EEPROM Hex”. Note that the evaluation module does not include an EEPROM, but an external EEPROM
can be used. SigCon Architect cannot directly program the EEPROM. The EEPROM Hex File can be
burned on the EEPROM via I2C communication (i.e. AARDVARK or equivalent interface adapter). The
EEPROM control settings are described in greater detail below.
• Common Channel: If this box is checked, all channels receive the same configuration. Different
devices can receive different configurations, but within one device, all channels will receive the same
configuration. If this box is unchecked, then the EEPROM will store the configuration as unique
channel configurations. Each of the four channels can receive a unique configuration.
• EEPROM>256:
– This setting must be enabled if there are more than 4 EEPROM slots.
– When this box is checked, the “EEPROM Size” drop down menu is automatically populated by 512
Bytes if previously populated by 256 Bytes.
– When this box is unchecked, the “EEPROM Size” drop down menu is automatically populated by
256 Bytes. Up to 4 EEPROM slots can be programmed.
• Enable CRC: If enabled, each device will have a CRC value specific to the base header, address map
header, and data. If disabled, the CRC is not computed.
• Slot Update Details: The number of slots refers to the total number of unique SMBus register settings
to load from the EEPROM. The user can choose to update all slots, or which slot # to update the
SigCon Architect EEPROM page from.

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• EEPROM Size: The EEPROM size must be set to 256, 512, or 1024 bytes. A single external EEPROM
can be used by up to 16 DS250DF810 devices.
– The first 3 bytes of EEPROM data is the base header. The base header contains the CRC enabled,
address map header enabled, EEPROM<256 bytes, device count, and maximum EEPROM burst
size settings.
– If multiple devices are programmed, an address map header is needed for each device. The
address map header specifies the CRC value and the Device EEPROM Start Address.
– EEPROM Size ≤256 Bytes:
• EEPROM Size = 3 Bytes (Base Header) + # of devices * 8 Bytes/device (Address Header) + #
of slots * 66 Bytes/slot (Data)
– EEPROM Size > 256 Bytes:
• EEPROM Size = 3 Bytes (Base Header) + # of devices * 12 Bytes/device (Address Header) + #
of slots * 66 Bytes/slot (Data)
2.2.4 High-Level Page
2.2.4.1 Overview
The High-Level Page on the Selection Panel enables the user to easily configure and/or check the status
of the DS250DF810 high-speed data path functional blocks: Clock and data recovery (CDR), Receiver
equalization, Transmitter output driver, PRBS generator and checker, and cross-point. The figure below
shows the landing page after uses selects “High-Level Page on the Selection Panel. The first button
option is the “Block Diagram”, an illustrative page highlighting the DS250DF810’s functional stages. The
configuration features for the additional tabs within the High-Level Page are described further in the next
sub-sections.
Figure 9. High-Level Page, with Block Diagram Tab Selected

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2.2.4.2 Device Status
In order to view a real-time high-level summary of the current device status and control settings, navigate
to the “High Level Page”, and choose the “Device Status” tab. Click “Refresh From Device” to ensure the
settings shown are from the device. The settings on this page are not editable.
• Signal Detect Status: For each channel the device status is displayed as “Signal Not Detected” if there
is no detectable signal present at the RX side of this channel or “Signal Detected” if there is a signal
present at the RX side of this channel.
• CDR Locked: For each channel the CDR lock status is displayed. Note that each channel’s CDR status
and configuration is independent from the others.
• EQ Boost: This field displays the Rx Continuous-Time Linear Equalizer (CTLE) boost value as a four
digit figure. Each digit corresponds to one of the four CTLE stages, and each can have a value from 0
to 3.
• DFE Taps: The boost values in mV for each of the five Decision Feedback Equalizer (DFE) taps are
displayed here.
• HEO and VEO: The HEO and VEO values in mV are displayed for each of the retimer channels.
• Tx FIR filter taps: The Device Status tab displays the current decimal value and polarity for the FIR
pre-cursor, main-cursor and post-cursor taps for each of the channels. The coefficient sum (i.e.
absolute sum of the FIR tap values) is also displayed. Finally, the page displays approximate values
for the effective post-cursor and pre-cursor de-emphasis based on the channel’s current FIR tap
settings.
Figure 10. High-Level Page, with Device Status Tab Selected

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2.2.4.3 Rx EQ/DFE
The Rx EQ/DFE tab provides the user with full status and control capability of the DS250DF810 Rx
equalization functions. The figure below illustrates the Rx EQ page functions, which are described below
in more detail.
Figure 11. Rx EQ/DFE Tab
• Adapt Mode
– Upon landing on the Rx EQ page, the GUI will display the current status for the retimer adapt mode
for the channel selected in the Channel Select pull-down.
– The Rx EQ page allows the user to set the DS250DF810 device to any of the four available adapt
modes. To do so, the user should click on the desired adapt mode then click “Apply to Channel” to
configure a specific retimer channel. Alternatively the user may broadcast the new adapt mode
setting by clicking on “Apply to all channels.”
• CTLE Settings
– Select the desired channel on Channel Select pull-down.
– The GUI will display the current CTLE boost value on the EQ Boost field of the CTLE Settings
section.
– If the user wishes to manually set the EQ value:
• Adapt Mode 0 may be selected (i.e. no adaption mode).
• Check the “Enable CTLE Boost Override” option.
• Click on “Reset CDR” button on the top right of page.
– Boost 3 Limiting bit
• When checked, this option configures the last CTLE boost stage to have a limiting output.
– VGA (Variable Gain Amplifier) gain bit
• When checked, it enables the Rx VGA block.
– EQ Hi gain mode bit
• When checked, the EQ is set to the high-gain mode of operation. This bit is enabled by default.

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– EQ boost table - If the user wishes to customize the sixteen value CTLE boost table:
• The user can enter the desired values individually on the “CTLE Boost Settings”.
• After entering all of the CTLE table values, the user should click on “Save as CTLE” button to
save the file.
• This CTLE table file can be loaded for use with new devices by clicking “Load CTLE” and
selecting the file from its location.
– DFE Controls
• Upon landing on the “Rx EQ” tab, the” DFE Controls” section will display the current weight
values and polarities for the five DFE taps for the selected channel.
• The user may check the “DFE Override” box to manually configure the DFE tap values.
• The user may enable continuous DFE adaption by checking the corresponding box on the “DFE
Controls” section.
2.2.4.4 Cross-Point Switch
The cross-point tab allows the user to easily configure the 2x2 cross-point implemented for each of the
adjacent channel pairs of the DS250DF810 retimer.
• With the “Pair Select” pull-down, the user can choose which cross-point pair to configure (0-1, 2-3, 4-5,
or 6-7.)
• The cross-point mode is selected using the “Crosspoint Configuration” pull-down.
• The cross-point channels mappings are illustrated on the “Crosspoint Settings” table on the page, and
the displayed color matches the current cross-point mode.
There are three cross-point configuration modes selectable via the “Crosspoint Configuration” pull-down:
• Default
– The transmitter for a given channel obtains data from its own receiver.
• Fanout
– Upon selecting the “Fanout” option on the pull-down, the user will be asked to select a channel on
the “Broadcast Channel” pull-down.
– After the user selects the broadcast channel and clicks on “Broadcast”, the received data for the
selected channel will be output both on its Tx output and also on the Tx output of its cross-point
pair channel.
• Lane Crossing
– Upon selecting the “Lane Crossing” option, the GUI will automatically configure the cross-point pair
in question such that the Tx output of a given channel obtains its data from the Rx of its adjacent
cross-point pair channel

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Figure 12. Cross-Point Tab, Default Mode Selected
Figure 13. Cross-Point Tab, Fanout Mode Selected

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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 DS250DF810 retimer to operate at the desired data
rates and sub-rates. The DS250DF810 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.
– Select the desired channel on Channel Select pull-down.
– The user first clicks on the “Standard Mode” option on the page.
– The user then selects the desired rate within the “Standard Data Rate Selection” Options.
NOTE: The default settings for the DS250DF810 are “Standard Mode”, and “100Gb Ethernet”
(i.e 25.78125 Gb/s data rate per channel).
• 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.

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• To configure a channel via “Manual Mode”:
– Select the desired channel on Channel Select pull-down.
– Select “Manual Mode” option on the page; the user will then see the manual mode input fields
become adjustable.
– Select the desired divider setting from the “Divider Configuration” pull-down.
• Select “divide-by-1” when data rate > 13 Gbps.
• Select “divide-by-2” when 13 Gbps ≥data rate > 6.5 Gbps.
• Select “divide-by-4” for data rate ≤6.5 Gbps.
– Enter desired Data Rate for group 0 then click “Write Rate Regs”. The GUI defaults to max PPM
tolerance.
– Enter desired Data Rate for for group 1 then click “Write Rate Regs”. The GUI defaults to max PPM
tolerance.
– Click “Reset CDR”.
Figure 15. CDR Tab, Standard Mode Selected

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Figure 16. CDR Tab, Manual Mode Selected

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2.2.4.6 TX FIR/VOD
The TX FIR tab allows the user to configure the FIR tap settings for each of the retimer channels, to set
the output to specific voltage amplitude and/or realize specific transmit pre-cursor and post-cursor
equalization ratios.
Figure 17. TX FIR Tab
• Upon landing on the TX FIR tab, the page will display the current decimal values and polarity for the
main-cursor, post-cursor and pre-cursor FIR taps.
• In addition, the page also displays approximate values for the voltage output differential (VOD) and the
de-emphasis for both pre-cursor and post-cursor.
• The user may adjust the FIR tap values, by clicking on the up/down arrows for each field. After
entering the desired value(s), the user can click on “Set Taps” to make the entries effective.
• At any point the user can click on “Read Taps”.

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2.2.4.7 PRBS Tab
The PRBS tab within the High-Level page allows the user to configure the PRBS generator or Checker
functions on any of the channels of the DS250DF810 retimer.
• To enable PRBS Generator on a channel:
– Select the desired channel using the “Channel Select” pull-down.
– Select the desired pattern using the “Pattern Type” pull-down.
– Set desired Polarity via pull-down, Non-Invert or Invert.
– Click “Enable” button.
Figure 18. PRBS Tab, PRBS Generator Configuration

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• To enable PRBS Checker on a channel:
– Select the desired channel using the “Channel Select” pull-down.
– Set the “Capture Period”.
• Set pull-down to “Infinite” if it desired to run extended duration test without time limit.
• If “Finite” period is desired, set the pull-down to “Finite” and enter the desired test duration via
the “Hours” and/or the “Mins(Minutes)” input fields.
• Click “Turn ON”.
• The user may clear the counter fields by clicking “Clear Checker,” or reset the PRBS checker
settings by clicking “Reset Checker”.
• To turn off the checker and return to default settings, click on “Turn OFF”.
Figure 19. PRBS Tab, PRBS Checker Configuration