When I am designing with FPGAs, I like being aware of their power consumption.
When FPGA power consumption is within your system power budget...
- Your system operates correctly
- You are not surprised during system power up
- Your system still functions well when you push the system speed and temperature
However, when FPGA power is over your system power budget...
- Your system can have functional problems under certain operating environments (note that advanced technology- 90nm or newer- FPGAs would have the highest power consumption at high temperature.)
- Peak power consumption could occur during power-up configuration from the external "boot" device (Flash or PROM).
To avoid potentially disastrous system issues, you need to be able to predict or be aware of your FPGA power consumption. Lattice provides a FPGA power calculator either as part of the ispLEVER development software or a power calculator as a standalone software for the FPGA designer to estimate device power consumption.
Lattice's power calculator has two main options to calculate your FPGA power consumption:
- Estimation mode: In an early stage of your FPGA design, you can simply enter the estimated number of functional blocks (PFU, EBR, I/O, etc.), operating frequency and device operating temperature (junction temperature). Based on this information, the power calculator will provide an estimated FPGA device power consumption. If your estimated numbers are close, you should be within approximately 20% of your final power requirements.
- Calculation mode: Once you have completed your FPGA design, your exact FPGA design netlist is loaded to the power calculator. With this exact functional block utilization data along with the frequency and temperature of device operation, you should be able to predict FPGA power consumption within 10%.
Gone are the days when you can simply read the power numbers from the data sheet and use those numbers to budget for system power supply. However, today's FPGA software tools can reasonably estimate power numbers that will work in your system environment.