T1040 rise and fall times for 3.3V

[adamgarrison]

In the T1040 datasheet, LVDD/L1VDD can be powered at 3.3V. However, in section 3.6.4 of the same datasheet, the Gb Ethernet reference clock parameters are only specified for IO voltages of 1.8 and 2.5V.  Table 18 has rise and fall time specs that are only given for 1.8 and 2.5V. Is there a spec floating around somewhere that gives the required max rise/fall times for 3.3V IO voltage?

[r8070z]

Have a great day,

I think it is supposed that 3.3V is for the MII interface only when the Gb Ethernet reference clock is not needed. So there is not the rise and fall time specs at 3.3V. The max rise/fall time at LVDD equal to 1.8V and 2.5V can be received as t = LVDD[V]*(0.8-0.2)/2[V/ns]. The same we can see in the RGMII signal specifications. For LVDD=3.3V this expression gives 0.99 ns. This value corresponds to the recommended value at 3.3V for some Freescale processors with the same requirement for the rise/fall time at 1.8V 2.5V. It says “Max rise/fall time of GTX_CLK125 is 1ns for 3.3V bank voltage. The rise/fall time is measured from 0.6V and 2.7V.”

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