# Measuring the external memory power consumption in FPGAs?

I am trying to get a power/energy breakdown of DDR3 and core logic. I used Quartus power analyzer tool to get the power estimates, but I am not sure whether it includes the power consumption of external memory like DDR3, HBM. In general, how do we measure/model the power consumption of the external memory access in Intel FPGAs?

• It's probably just the FPGA. how is the software suppose to know everything else? – DKNguyen Sep 2 '19 at 18:40

Power analyser tool estimates the power consumption by the FPGA alone due to all the connected peripherals. To calculate the power consumption of the off chip peripherals, datasheets are really your friends

1. Consider all static power consumptions
2. Calculate dynamic power consumptions due to switching load ($$\n \times V^2 \times f \times C\$$)
3. how exactly to calculate depends on teh applicaiton, components and the usage
4. For example, if there is an external flash, you can calculate current needed for a simple read, fast read, idle condition and write at particular planned clock frequency. and then, estiamte how much percentage each task will happen over a period of time. the current consumtion than can be scaled accordignly.
5. Also, consider quiscent current for deivces which are not switched during operation
6. Other loads such as toggling LEDs, RF transmission etc

All theory can be well verified with practical current mesurement. Consider datasheet maximum for worst case.

You measure the power using appropriate measuring instruments to monitor the actual current consumed and the actual voltage.

You model the power consumption by adding the estimated power consumption of all of the components of the system. For each component you use the datasheet to estimate the power consumed for your specific usage scenario. It's as simple...and as difficult...as that.

• Okay. Is there a way to estimate the off-chip memory power using software like Quartus power analyzer without dumping the design to the actual hardware? or do we need to use the datasheets to do that? – Shreyas Kv Sep 2 '19 at 18:36
• If the memory manufacturer provides a tool for estimation then by all means use it. If not, look for the appropriate information in the datasheet. – Elliot Alderson Sep 2 '19 at 19:02

I haven't seen a power estimation tool for memories. This is the method I use:

The memory datasheet will provide the current consumption for each of the different types of cycle at a specific rate. (e.g. Write cycle, read cycle, refresh cycle, burst read, idle, etc).

You have to define what your usage pattern for the memory will be in terms of the rates for each of those cyles. Then it is a relatively straightforward exercise with a spreadsheet to sum up all those power consumptions.