Xilinx RocketIO User Manual

Also see for RocketIO: User guide User guide User guide

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Xilinx RocketIO User Manual Manual pdf 107 page image

RocketIO™ Transceiver User Guide www.xilinx.com 107UG024 (v2.3.2) June 24, 2004 1-800-255-7778PCB Design Requirements RFor further clarity, TXUSRCLK is used to clock data from the FPGA core to the TX FIFO. TheFIFO depth accounts for the slight phase difference between these two clocks. If the clocks arelocked in frequency, then the FIFO acts much like a pass-through buffer.PCB Design RequirementsTo ensure reliable operation of the RocketIO transceivers, certain requirements must be met by thedesigner. This section outlines these requirements governing power filtering networks, high-speeddifferential signal traces, and reference clocks. Any designs that do not adhere to these requirementswill not be supported by Xilinx, Inc.Power ConditioningEach RocketIO transceiver has five power supply pins, all of which are sensitive to noise. Table 3-5,summarizes the power supply pins, their names, associated voltages, and power requirements.To operate properly, the RocketIO transceiver requires a certain level of noise isolation fromsurrounding noise sources. For this reason, it is required that both dedicated voltage regulators andpassive high-frequency filtering be used to power the RocketIO circuitry.Voltage RegulationThe transceiver voltage regulator circuits must not be shared with any other supplies (includingFPGA supplies V CCINT, V CCO , V CCAUX , and V REF ). Voltage regulators may be shared amongtransceiver power supplies of the same voltage; however, each supply pin must still have its ownseparate passive filtering network. (See Figure 3-7.)Table 3-5: Transceiver Power SuppliesSupply 2.5V 1.8V -2.625V1.5V -1.8VPower(1) (mW)DescriptionDCCoupledACCoupledAVCCAUXRX √ 90 90 Analog RX supplyAVCCAUXTX √ 130 130 Analog TX supplyVTRX (2) √ √ 37.5 (3) 0 (3) RX termination supplyVTTX √ 37.5 (3) 75 (3) TX termination supplyGNDA N/A N/A Analog ground for transmit andreceive analog suppliesNotes:1. Power at max data rate. Power figures shown do not include power requirements of VCCINT (28 mW) and VCCAUX(48 mW), which power the PCS and PMA respectively.2. See section “AC and DC Coupling,” page 114, and Table 3-7 for VTRX supply restrictions in AC- and DC-coupledcases.3. These numbers are based on VTTX at 2.5V for the DC- and AC-coupled cases; VTRX at 2.5V for the DC-coupled case,and 1.8V for the AC-coupled case.