JackBurton wrote:I believe only the SDRAM XS can do 167 MHz but none of the cores use it. The rest of the SDRAM setups can do up to 160 MHz.
Not totally right ... I've had also UNI Ram modules that pass 167MHz ON MY BOARD.
But this is not generally so - yes the possibility that a XS passes the 167MHz is higher than for a Universal one, but:
- Depends on the DE10 board
- Depends on the noise in your power line
- Depends on the Ram Chip itself (corner sample)
- on many other things.
The SDRam Chips are 6ns - if you calculate the max frequency is 166.6666 MHz
So the 167Mhz is the absolute maximum.
I'm still fascinated that the modules work at this frequency at all.
In a classic PCB design you would place the memory near to the chip. Will have an eye on the impedance and track length and use normally a 4 Layer board.
Here we have connectors in between, just 2 layers and so on - I'm really impressed that it works at all - here you can see which kind of great job Sorgelig has done!
And: The core with the highest need is the MiniMig with 114.75Mhz.
Sorgelig mentioned that everything above and equal 140MhZ is fine!
So the main difference between XS and UNI is the size and that the UNI can be build horizontal.
In the vertical way the UNI will set the max hight of the system and you will not be able to use the XS Case with a UNI one - that's it!