[SOLVED] CAS Latency and Frequency relationship

[imbichie]

CAS Latency and Frequency relationship in DDR

hai friends,

i have a ddr of samsung with "memory clock frequency: 133MHz@CL2, 167MHz@CL2.5". now i am working with a freq of 96Mhz with CAS latency CL2, now i wants to work with a freq of 144Mhz; so when i going for that, is it needed to change the CAS latency from CL2 to CL2.5

Thanks in Advance

 

[zel]

Re: CAS Latency and Frequency relationship in DDR

hi..i think no. you dont need to change the CAS Latency. if im not wrong the CAS Latency is depend on ddr SPEC.

 

[imbichie]

Re: CAS Latency and Frequency relationship in DDR

Thank you for your reply
in my ddr spec its given that "133MHz@CL2, 167MHz@CL2.5", so if i am working with 144Mhz, which CAS Latency should i used???

 

[permute]

2.5 is safe.
2.0 might be possible. see the datasheet for more info.
CAS is based on a time. This has to be converted to a number of cycles or half-cycles.

 

[imbichie]

thanks a lot

 

[qieda]

Hi,

I think you should find in the datasheet a table, which looks similar to this

Unit Note Min Max
Clock cycle time CL=2 tCK 12.0 ....
CL=3 6.0 ...

this gives you the min and max clock cycle time for the selected CL

 

[imbichie]

Now the issue solved i put CL as 2.5,
thanks to everyone