Some time ago, I wrote, “The Actel/Microsemi parts have one additional advantage: They have the best static power consumption in the industry.” I was wrong.
Last month, a post on the geda-user mailing list alerted me to SiliconBlue Technologies and their line of ultra-low-power FPGAs. These FPGAs are RAM-based, like those of the big two FPGA manufacturers, Xlinix and Altera. Unlike the chips from the big guys, though, SiliconBlue’s parts are not power hogs. In fact, they are fully static and go down to microamps with a static clock. With the Microsemi (Actel) FPGAs, one has to freeze the FPGA with the “Flash Freeze” feature to get down to that level, but it appears that the SiliconBlue units simply clock right down there. If true, that would give them quite an edge in power-conscious design.
Making a direct comparison between the Actel/Microsemi Igloo line, their lowest-powered, and the SiliconBlue parts has to be done on a case-by-case basis. The clock rates, and in particular, how often the clocks can be stopped, matter a lot. There is also the external configuration EEPROM for the Silicon Blue parts, which will take power in simple designs, but can be powered down or perhaps eliminated in more sophisticated uses.
In any event, I will stick with the Microsemi ProASIC3 and Igloo line for now. I like the convenience of a flash-based architecture. The next time I’m designing for low power, though, it will be time to give SiliconBlue a good look.
Updated 5/12/11: The date of the geda-user post was corrected.
- SiliconBlue Technologies (www.siliconbluetech.com)