SDRAM nominal frequency question

Thread Starter

mos_6502

Joined Dec 11, 2017
65
It is possible to use a SDRAM with lower frequency that its nominal frequency?
I'm using a SDRAM that have nominal frequency at 143 or 166MHZ, can I use this SDRAM with 80MHz clock?
 

Thread Starter

mos_6502

Joined Dec 11, 2017
65
Yes, I imagined it could be a problem with refreshment times. I'm driving my SDRAM with an FPGA and I have a specific FSM to do so which also includes the parameterization of the refresh times. Having a lower clock I think you have to increase the refresh rate, do it more times than what is established by the nominal data. Is my reasoning correct?
 

Papabravo

Joined Feb 24, 2006
21,003
Yes, I imagined it could be a problem with refreshment times. I'm driving my SDRAM with an FPGA and I have a specific FSM to do so which also includes the parameterization of the refresh times. Having a lower clock I think you have to increase the refresh rate, do it more times than what is established by the nominal data. Is my reasoning correct?
IIRC there is a maximum time between refresh cycles. We never pushed up against that limit very hard. We did have smaller chips by at least several orders of magnitude.
 
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