By the way, Actel is now part of Microsemi, with all that it entails. Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things... -----Original Message----- From: Jim Lux <jim...@earthlink.net> Sender: time-nuts-boun...@febo.com Date: Sat, 28 Apr 2012 14:19:40 To: <time-nuts@febo.com> Reply-To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Subject: Re: [time-nuts] PICTIC II ready-made? On 4/28/12 12:10 PM, shali...@gmail.com wrote: > I have not studied CPLDs but Actel has the only true Flash based FPGAs. The > flash cells directly control the FPGA fabric. As such, they are mostly immune > to Single Event Upset that plagues just about any other FPGA technology, and > there is no configuration step at power up. mmmm.. the flash contents can still be lost(although Actel claims that their flash is pretty neutron and alpha particle immune.. but heavy ions?).. the Actel anti-fuse parts, like the AX and RTAX series, have logic that can't be changed. We use a lot of the Actel flash parts (ProASIC3) for prototyping, then burn it to an rtax for final. I think there's a similar path for the 54SX parts (i.e. a reprogrammable version and an antifuse OTP part) Here's what was in a Brookhaven report about using FPGAs in PHENIX The Actel FPGAs do not have SRAM configuration memory so they are immune to this form of upset. FLASH memories exhibit dissipation of the charge on the floating gate after 20kRad of integrated dose. The dissipation is not permanent damage and is remediated by reprogramming the device. Flash memories also displayed SEE problems during programming during radiation exposure that included gate punch-through, a destructive effect. These types of SEEs are avoided by not programming the FLASH under radiation exposure conditions, namely during machine operation. Practically speaking 20kRad is a fairly decent dose (it's a typical design requirement for a trip to Mars or for GEO).. you pick up about a kRad/year In LEO it's a lot lower (otherwise astronauts in ISS would die). Around Jupiter it's a lot higher (typical design requirements for Europa missions and such are 1 MRad) _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.