relacing 5V TTL tolerant FPGA with 3.3V TTL I/O tolerant FP

[balu304]

Hi
We used old spartan device which was 5V I/O tolerant. That device is obsolete one.Now, we are going to replace with new FPGA (SPARTAN3 series).But,these devices which are now in market are 3.3V tolerant only.How to face this problem?
Please suggest me.
regards,
Balu

 

[cherukukeshav]

Re: relacing 5V TTL tolerant FPGA with 3.3V TTL I/O tolerant

you have to go for respin of the board. it u want to use 5v with the new layout also , then use level translators at FPGA I/o's. But It will increase the BOM cost of the board.

- Keshav

 

[FvM]

Re: relacing 5V TTL tolerant FPGA with 3.3V TTL I/O tolerant

Series resistors in combination with the built-in clipping diodes may be sufficient in some situation. Consult the respective manufacturer device handbooks and appplication notes.