Answers Database XC2000L/XC3000L/XC4000L: Estimating power consumption for 3.3V Devices (2000L, 3000L, 4000L) Record #1520 Problem Title: XC2000L/XC3000L/XC4000L: Estimating power consumption for 3.3V Devices (2000L, 3000L, 4000L) Problem Description: Urgency: standard Description This is a guideline for estimating power consumption for our low voltage (3.3V) devices. For more information regarding estimating power consumption in FPGAs please refer to the 1996 Databook. Solution 1: Since our 3.3 volt devices have the same architecture as thier 5V counterparts and almost all power (except Icco) is dynamic, the power changes with the square of the supply voltage. That means, at nominal 3.3 V, the power is 43.6 percent of the power at nominal 5 V. If you use the mac commercial values, 3.6 V and 5.25 V, then it is 47 percent. Based on this information, the following figures may be used to estimate possible power consumption of a design : Device CLB Output Clock Longline ------ ------- ------- ------- --------- XC2018L 0.048 0.349 1.40 N/A XC3090L 0.052 0.349 0.87 0.031 XC4005L 0.065 0.392 1.74 0.044 XC4010L 0.065 0.392 3.49 0.065 XC4013L 0.065 0.392 5.01 0.078 where : all units given in "milliwatts per million transitions                per second" "CLB" = one CLB driving three local interconnects "Output" = one output driving 50 pF "Clock" = one global clock line connected to all flip-flops "Longline" = one split Longline "CLB" and "Output" are independent of device size. "Clock" is proportional to the number of CLBs, i.e. to the   gate count. "Longline" power is proportional to the square root of the   number of CLBs, or the square root of the gate count. Note : For very low power watch out for the high Icco of the XC3100L ( due to gate pumping ), and the ficticiously high Icco of the XC5200L, due to anticipated future gate pumping. End of Record #1520 - Last Modified: 09/12/97 09:01

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