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NetFPGA-SUME™ Reference Manual
2.5
Power Consumption
The power consumed by the NetFPGA-SUME is largely dependent on the number of resources utilized by a given
design, and the complexity of that design. This makes estimating power consumption for any particular application
difficult. However, during the design process it was necessary to estimate the worst case scenario power
consumption for each of the supply rails and to come up with a total power budget. Table 4 lists the supply
voltages, their rated output current, and the maximum power that they can output.
Supply Rail
VCC1V0
VCC1V5
VCC1V8
VCC2V0
VCC3V3
MGTAVCC
MGTAVTT
VCC12V0 (FMC)
VCC12V0 (FPGA FAN)
Note: The output power of the DDRVTT, MGTVAUX, and QDRVTT rails are not listed because these supply rails are
derived from the VCC3V3 rail.
Maximum Output Power: 40+22.5+27+4+49.5+8+3.6+12+0.6=167.2 Watts
The actual power consumed from the input supply is greater than maximum output power due to the switching
regulators not being 100% efficient. The switching regulators used on the NetFPGA-SUME were designed to
operate at approximately 90% efficiency. The total power consumed from the input supply can be as high as
((40+22.5+47+4+49.5+8+3.6)/0.90)+12+0.6=184.4 Watts. However, this number can be a bit misleading as it
assumes that a mezzanine module is attached to the FMC connector and is drawing the maximum allowable
current from the VADJ, 3P3V, and 12P0V rails simultaneously.
According to the FMC specification, which is defined by ANSI/VITA 57.1, an FMC carrier card (NetFPGA-SUME)
must be capable of supplying 4A to VADJ (1.8V, VCC1V8), 3A to 3P3V (3.3V, VCC3V3), and 1A to 12P0V (12.0V,
VCC12V0). This implies a total input power consumption of ((4*1.8)+(3*3.3))/0.9+(1*12)=29.1 Watts by the FMC
mezzanine module. However, ANSI/VITA 57.1 says that mezzanine modules may dissipate a maximum of 10 Watts.
This means that the maximum output power is actually 167.2-(29.1-10)=148.1 Watts.
Determining the input power consumption after taking into account the 10 Watt output power limitation of the
FMC connector is difficult, as we do not know which supply rails will be utilized by an attached FMC mezzanine
module. Assuming that all power was consumed from VADJ and 3P3V, the total input power consumption would
be reduced by 12+((19.1-12)/0.9)=19.9 Watts. As a result, the input power consumption could be as high as 184.4-
19.9=164.5 Watts when an FMC mezzanine module is attached. If no FMC mezzanine module is attached, then the
maximum input power consumption is (40+22.5+(1.8*11)+(3.3*12)+8+3.6)/0.9+0.6=153.4 Watts.
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Nominal Voltage
Rated Current
1.0V
40A
1.5V
15A
1.8V
15A
2.0V
2A
3.3V
15A
1.0V
8A
1.2V
3A
12.0V
1A
12.0V
50mA
Table 4. Supply rails and their maximum power output.
Maximum Power Output
40W
22.5W
27W
4W
49.5W
8W
3.6W
12W
0.6W
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