SDRAM Question

[udylevy]

Hi all,

I am trying to understand how SDRAM works, but some things I don't understand:

1) Do I have to refresh while I am in burst cycle (say I am in full BANK write mode), if so what happens after refresh is finished, do I have to activate row again, or can I just keep writing.

2) What is the actual data rate (typical) for a 133MHz SDRAM?

3) does auto refresh follow PRECHARGE command?

4) Finally- why is SRAM considered faster thqan SDRAM, I checked an SRAMs by Toshiba, and as far as I understood, it's data rate was 16MHz, so this doesn't seem so fast to me, what am I not understanding here?

 

[j.p.bill]

Getting the spec sheet for any SDRAM will answer your questions 1 - 3. The data rate on that SRAM sounds awfully slow.

 

[ronsimpson]

udylevy,

What part number? 16mhz is too slow maybe 160mhz.

 

[udylevy]

SRAM part number is TC55257 by Toshiba. The Data Setup time is 60nS, so doesn't this prevent working frequency to >=16MHz?

 

[udylevy]

Getting the spec sheet for any SDRAM will answer your questions 1 - 3. The data rate on that SRAM sounds awfully slow.

I did look at the spec, but I am not sure I understood it right. My main question is what is the actual data rate of the SDRAM, since it's not specified directly in the datasheet, I need to understand how it works to calculate it.