Originally Posted by
kaseki
I found that I had another different Samsung document than I referred to earlier. An extract of the state table for RTT is below. One can see that with
The Stilt's recommendation {nom disabled, wr disabled, park RZQ/5} that RZQ/5 is always used. RZQ/5 is 48 ohms per this document. This value might be expected to reasonably match likely trace impedances, although what the relevant C6H trace impedances are is unknown to me.
Conversely, more or less, the
Ramad/Jackalito/HarrySun values of {nom RZQ/3, wr RZQ/3, park RZQ/1} when applied to the state table yield a termination resistance that fluctuates. I'm not sure what advantage that would have.
I'm not certain what your recommendation of {auto, auto, auto} actually does, so I'll just add that to my test matrix. Edit: Discovering an earlier message I missed, I think this is
The Stilt's {disabled, disabled, 48 ohm} condition.
For reference, I am presently running RZQ/2 on 1403 for all three parameters from a month-ago recommendation by
BoMbY. He didn't answer my question about his rationale for these values. My present thinking is that these impedances may be too high for good matching.
And then there is
The Stilt's spasm version of 1403 still to test. Sigh.
from
DDR4 SDRAM Specification, Device Operation & Timing Diagram, 2014, page 178
The circuit diagram (simpified, I'm sure) extracted below suggests why there may be a change in DRAM power usage. The lower the terminating resistor, the more current flows to the signal lead and thence to eventually to ground. There are a lot of terminating resistors.