We are want to use a spartan 3E in the very small chip scale package because of space constraints. However the 4 MBit serial prom for this device is almost the same size as the whole fpga. Does anybody know of an alternative which is much smaller? Taco Walstra University of Amsterdam
1) Don't know how much this helps, but if you're using the 3S500E and don't fill the part up too much, your bitstream can fit into a 2 Mbit prom if you compress it. Banking on that however can lead to problems if your design expands and the compressed bitstream grows over the 2 Mbit boundary. 2) Do you have some other storage available that could be shared to with the bitstream data? A microcontroller with attached flash? A 120 Gbyte hard drive attached via the host system interface? Or does your FPGA need to come up running without any support from software? 3) Any chance of using a Lattice XP2 in the 132-ball csBGA instead (no external prom required)?
there are QFN versions of SPI flash available, they much smaller. I also have a desing where SO-8 package is HIGHEST component and almost the same size as QFN132 packaged FPGA. I used SO-8 as it is few cent cheaper than QFN SPI flash.
Antti Lukats
I don't know yet if it fits in a 2 MBit prom because it depends on some cores not yet written. what do you mean with 'compress'? There is no processor available for some kind of uncompressing it during power up, the fpga should just 'boot' from the prom.
no not really a 120 GB drive available. The whole system should be fitted on a few cm.flexprint, the microcontroller/RAM etc. is part of the FPGA.
Mm, good tip. I'll investigate that line. thanks. Taco
check at Xilinx web for the Spartan 3AN.
S3-AN is not availalable in small packages :( so s3e-132+qfn flash take less space than smallest s3an
Antti
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