Dear everybody,
I have to design an ALTERA Cyclone FPGA based board which will be used in a rugged environment in terms of operating temperature (-40 to +85 =B0C) and strong EMI interference. I have to provide for the clock to the FPGA and I would like to use a 16 MHz oscillator which will be multiplicated by 8 by the Cyclone internal PLL in order to obtain a 128 MHz clock for the NIOS II processor.
My doubts are the following:
- is a good choise to connect directly the oscillator output to the FPGA pin or for this kind of environment is suggested to build a more reliable circuit around the oscillator ?
- is a good choise using the internal PLL ? Is it reliable in a rugged environment ? (I have chosen an external low frequency oscillator to reduce EMI emissions)
- are there exist on the market any oscillator specifically designed for rugged environment ?
Hope someone of you have already experienced these kind of problematics in order to suggest me the best way to run.
Best Regards
/Alessandro Strazzero