hfss_newbie
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can we change the internal memory(DDR2) clock? is there a crystal clock inside?
Hello guys,
Here is my question. i have bought a DDR2 memory and when i look at the datasheet, it doesn't talk about the internal clock freq. of DDR2.
Does it mean that there is no crystal clock inside? if not is the working freq. supplied by DDR2 controller? or by clock tree which is completely independant of DDR2 controller?
when i buy a DDR2, is the speed grade fixed or we can program it?
in order to see where my confusion comes from, below is the table of speed grade in datasheet of Micron DDR2 that i've bought. it shows different speed grades, and i believe it means that i can program my DDR2 internal clock to have these speed grades on I/O bus which comes out of DDR2.
Key Timing Parameters(Data Rates(MT/s)
Speed Grade CL = 3 CL = 4 CL = 5 CL = 6 CL = 7
-187E 400 533 800 800 1066
-25E 400 533 800 800 n/a
-25 400 533 667 800 n/a
-3 400 533 667 n/a n/a
Is that true?
thanks for any comment
Hello guys,
Here is my question. i have bought a DDR2 memory and when i look at the datasheet, it doesn't talk about the internal clock freq. of DDR2.
Does it mean that there is no crystal clock inside? if not is the working freq. supplied by DDR2 controller? or by clock tree which is completely independant of DDR2 controller?
when i buy a DDR2, is the speed grade fixed or we can program it?
in order to see where my confusion comes from, below is the table of speed grade in datasheet of Micron DDR2 that i've bought. it shows different speed grades, and i believe it means that i can program my DDR2 internal clock to have these speed grades on I/O bus which comes out of DDR2.
Key Timing Parameters(Data Rates(MT/s)
Speed Grade CL = 3 CL = 4 CL = 5 CL = 6 CL = 7
-187E 400 533 800 800 1066
-25E 400 533 800 800 n/a
-25 400 533 667 800 n/a
-3 400 533 667 n/a n/a
Is that true?
thanks for any comment