Virtex-4 RocketIO MGT User Guide www.xilinx.com 151UG076 (v4.1) November 2, 2008Special Analog FunctionsRPOWERDOWNPOWERDOWN, RXPD, and TXPD are used to reduce power. Table 4-7 through Table 4-9show the definitions of POWERDOWN, RXPD, and TXPD.POWERDOWN is a single-bit primitive port (see Table 1-7, page 47) that allows shuttingoff the MGT in case it is not needed for the design or is not transmitting or receiving for along period of time. When POWERDOWN is asserted, the PCS does not use any power.The PCS clocks are disabled and do not propagate through the core. DuringPOWERDOWN, the current to TXP/TXN is turned off. The 50Ω connection to V TTX isalways connected, creating the termination value. Any given MGT that is not instantiatedin the design is automatically set to the POWERDOWN state by the Xilinx ISE®development software and consumes no power.Table 4-6: PLL/Data Frequency Divergence as a Function of Lock and HysteresisHysteresis000(±4)001(±8)010(±16)011(±32)100(±64)101(±128)110(±256)111(±512)Lock Counter000 16,384 0.024% 0.049% 0.098% 0.195% 0.391% 0.781% 1.563% 3.125%001 8,192 0.049% 0.098% 0.195% 0.391% 0.781% 1.563% 3.125% 6.250%010 4,096 0.098% 0.195% 0.391% 0.781% 1.563% 3.125% 6.250% 12.50%011 2,048 0.195% 0.391% 0.781% 1.563% 3.125% 6.250% 12.50% 25%100 1,024 0.391% 0.781% 1.563% 3.125% 6.250% 12.50% 25% 50%101 512 0.781% 1.563% 3.125% 6.250% 12.50% 25% 50% 100%110 256 1.563% 3.125% 6.250% 12.50% 25% 50% 100% DisableLock=0111 128 3.125% 6.250% 12.50% 25% 50% 100% DisableLock=1DisableLock=0Table 4-7: RocketIO Transceiver Power Control DescriptionPOWERDOWN Function0 PCS and PMA function normally.1 PCS is in power down mode.Table 4-8: PMA Receiver Power Control DescriptionRXPD FunctionTRUE Powerdown the receiver.FALSE Normal receiver operation.
