Low power consumption board with memory

I think you will find that most of the FPGA out there will suck up more than 100 mA even if clocked slowly. Of course this depends on how large of an FPGA you have and how much of it you use. Still, it would be hard to find and FPGA board to run on 100 mA. You would do much better looking for a CPLD board. Xilinx makes two lines of low power CPLDs that can do a lot of work. One is 5 volt tolerant "XCR" and the other uses a lower voltage core "XC2".

I found some boards at Digilent,

The XCR board claims to run from a couple of AA batteries for 60 hours.

Here is one sold by Nuhorizons, but also made by Digilent...

You will have to contact them about the price.

Good AAs are 2800 mA-Hours. 60 hours would be 46 mA.

You probably get a net gain if you run through a switching regulator as compared to a LDO.

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Duccio

I will take on board what everyone else has said and say that a CPLD like Coolrunner2 is the best chance of low power. However sometimes CPLDs are not big enough for what you want to do. Another thing to say is that the static currents in a SRAM technology based FPGA like Xilinx or Altera parts will eat most of your power budget if not exceed it. Some of more fringe parts from Lattice, Quicklogic and Actel will do better in this respect so might be worth looking there if it is a FPGA you need. The downside of these manufactures is that they don't have the same range of development boards available to choose from but you may be lucky and find exactly what you need.

To give you some real numbers with Xilinx parts we have seen our Broaddown2(BD2-400- Spartan-3 XC3S400) operating at about 120mA at 5V input. These are real numbers to give you an idea. We have seen x2 and x3 than that with some general designs. Our regulator chain is totally made up of linear regulators so the current seen at the input represents the sum of all currents used on the board.

Another point to watch is that your minimum voltage is less than most of the CPLDs out there will operate down to. FPGAs like Spartan-3 do have a core that will operate at 1.2V but given your variance of input voltage you would need a regulator that itself may need a higher voltage than that to regulate. What you may need to do is to have a switching supply to stabilise your solar input before use or given you have a solar input a battery to hold level that charges when you have good sunlight and a decent input level.

Given that I don't know what you are trying to do on this design there may be other ways to tackle your power consumption. The first is to consider if your system needs to be working all of the time or could you wake it up for a time to do whatever task then power it off. Given you are asking for EEprom you may be doing this already. If this is the case and your ratio of "on" time to "off" is mainly off then strongly consider the battery method to achieve your needs.

Now given those ideas here is my commercial - Raggedstone1 has a 16Kbit serial EEporm on board. Can take more on DIL Headers if standard 3.3V EEprom in DIL package is fitted. This board is Spartan-3 based so my comments about SRAM based FPGAs do apply. I may also able to find and give you one of prototypes of this board with the linear regulators removed or disabled. You could then add your own switching regulators. You would have to the work yourself to build and add the switching regulators but otherwise it won't cost you anything. Enterpoint has a program with the very original name of UAP (University Access Program) where we do try to help institutions and students achieve projects. Details of UAP are here

John Adair Enterpoint Ltd. - Home of Raggedstone1. The ?75 Student FPGA Development Board.

Thanks to all for your help. The most important requirement of the board is that it must have a non-volatile memory so I can power-off it on the night (when there isn't thr sun that recharge the battery via solar panel), thus I'm oriented to the XCR board (that also don't cost so much).

Bye