DDR2 DQSn Pin Question

[Altera_Forum]

Hi, All 

 I am using Cyclone III and DDR2 as memory, I found there is no DQSn Pin in CycloneIII device. So how to connect DQSn pin in DDR2 memory device. Connect to Vtt=0.9V or GND, or somewhere else?   Thanks

[Altera_Forum]

Hi,  

it depends.  In DDR2, the DQS signal may either be single ended or differential. Take a look in your DDR2 device's datasheet about this.  If you are using a diferential DQS, then you need to set the DQS signal to the a differential SSTL I/O standard. The DQS_n signal will then be automatically assigned to the proper pin.

[Altera_Forum]

--- Quote Start ---  Hi,  it depends.   In DDR2, the DQS signal may either be single ended or differential. Take a look in your DDR2 device's datasheet about this.   If you are using a diferential DQS, then you need to set the DQS signal to the a differential SSTL I/O standard. The DQS_n signal will then be automatically assigned to the proper pin.  --- Quote End ---     But I can not find any DQSn pin in the Cyclone III device, is that means CIII device can not support differential DQS mode?   Thanks

[Altera_Forum]

Cyclone III documentation says that Differential SSTL is only supported on dedicated clock input and dedicated PLL output pins. 

 Thus, I'm afraid that, no, you can't use a differential DQS in a Cyclone III.

[Altera_Forum]

Unless you make a psudo-diff pin set by taknig the signal and it's inversion - placing them next to each other and adding proper termination on the board. THen it will be a mtter of the speed you are looking to obtain - best to do some PCB simulation with something like HyperLinx to make sure it all works. 

 Regards,  Avatar