MT40A512M16HA-083EIT Datasheet, PDF (121/373 Pages) Micron Technology – Programmable data strobe preambles

8Gb: x4, x8, x16 DDR4 SDRAM
V_REFDQ Calibration
value may not be exactly within the voltage range setting coupled with the V_REF set tol-
erance; the device must be calibrated to the correct internal V_REFDQ voltage.
Figure 65: Example of V_REF Set Tolerance and Step Size
V_REF
Actual V_REF
output
V_REF set
tolerance
V_REF set
tolerance
V_REF
step size
Straight line
(endpoint fit)
Note: 1. Maximum case shown.
Digital Code
V_REFDQ Increment and Decrement Timing
The V_REF increment/decrement step times are defined by V_REF,time. V_REF,time is defined
from t0 to t1, where t1 is referenced to the V_REF voltage at the final DC level within the
V_REF valid tolerance (V_{REF,val_tol}). The V _REF valid level is defined by V_REF,val tolerance to
qualify the step time t1. This parameter is used to insure an adequate RC time constant
behavior of the voltage level change after any V_REF increment/decrement adjustment.
Note:
t0 is referenced to the MRS command clock
t1 is referenced to V_REF,tol
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8gb_ddr4_dram.pdf - Rev. G 1/17 EN
121
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