Hello Everybody,
I wanted to collect some posts together and add new questions for a certain purpose.
Project has 8 EP3C25 fpgas and one MCU which controls and configurates (passive serial) of the fpgas. I want to keep the fpga's on LOW POWER stand-by mode (or Reset Mode) untill the MCU recieves a command to calculate something. After that MCU will let the fpgas RUN in NORMAL Mode, calculate the thing and put the fpga's into LOW POWER stand by mode again.
For this purpose i have some ideas and need your opinions about this stuff.
1- MCU can use the enable/disable pin of the oscillator. When fpga will not switch, power will be lowered. Here we need some delay after re-enabling oscillator but it is not a problem for the project.
2- nCONFIG pin can be held LOW to keep fpgas in Reset mode. (1-Does this work? 2- Can i keep it in reset mode forever without damaging the fpga?)
3- there are three power supplies, (1.2V core, 2.5V PLL, 3.3V I/O) MCU is also supplied by 3.3V. if i enable the 3.3V smps always and let the other supplies enabled by the MCU; MCU will decide if the 1.2V and 2.5V supplier smps's will work or not. this option looks more effective for me but fpga's will always recieve 3.3V but 1.2V and 2.5V will be switched on/off, can this situation damage the fpgas?
I need your opinions of efficiency of these methods and of course additional more smart ideas of yours.
Which method should i use?
Thanks and Best Regards..
