Datasheet
IMPORTANT WEB LINKS:
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Link to the TI home page for Xilinx FPGA power management solutions at
http://www.ti.com/xilinxfpga for more information and other reference designs.
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Link to datasheets at http://focus.ti.com/lit/ds/symlink/TPS54610.pdf and
http://focus.ti.com/lit/ds/symlink/tps79425.pdf.
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Link to SWIFT
TM
design software tool at
http://focus.ti.com/docs/toolsw/folders/print/swift-sw.html to assist further
optimization/customization of design.
IMPLEMENTATION NOTES:
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Sequencing: Although Xilinx FPGAs do NOT require it, this reference design
employs sequencing. This practice is consistent with good power supply design
and prevents the input power supply from being pulled down due to supporting
in-rush currents for charging large capacitive loads.
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Additional Capacitance:
o The TPS54610’s have been compensated to allow for up to the following
additional capacitance on each rail:
§ 12 uF in ceramics in parallel with
§ two 330 uF capacitors, each with ESR between 0.1 and 2 ohms.
If more bypass capacitance or bulk capacitors with ESR outside the range
above is used, each TPS54x10 control loop may need to be re-
compensated using the SWIFT design software.
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V
CCAUX
: V
CCAUX
powers time-critical resources in the FPGA, including the
Digital Clock Managers (DCMs). Therefore, this supply voltage is especially
susceptible to power supply noise. V
CCAUX
can share a power plane with V
CCO
,
but only if V
CCO
does not have excessive noise. Changes in V
CCAUX
voltage
beyond 200 mV peak-to-peak should take place no faster than 10 mV per milli-
second.
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RocketIO: When powering the RocketIO:
o A
VCCAUXTX
, V
CCAUXRX
, A
VTRX
, and A
VTTX
may each be powered by their
own linear regulator or by the same regulator if their voltages are the same.
Keep power dissipation capability of the linear regulator package in mind.
o Select the appropriate TPS79xxx or TPS786xx based on the load current
requirement, and the power dissipation capability of the package. In
general, the lower the current rating, the lower the price of the linear
regulator. Power dissipation of linear regulators is explained in TI
Application Note SLVA118.
o For the TPS79x01 adjustable devices, size the feedback resistors
according to the datasheet. These resistors are not populated on the
schematic.
o All unused RocketIO transceivers must be connected to power (2.5V) and
ground.
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Modifications: