Datasheet

Table 25. AC parameters of VREFDQ training
Symbol
Parameter
Min.
Max.
Unit
t
VREFDQE
Enter V
REFDQ
training mode to the first valid command delay
150
-
ns
t
VREFDQX
Exit V
REFDQ
training mode to the first valid command delay
150
-
ns
Example scripts for V
REFDQ
Calibration Mode
When MR6 [7] = 0 then MR6 [6:0] = XXXXXXX
Entering VREFDQ Calibration if entering range 1:
 MR6 [7:6] = 10 & [5:0] = XXXXXX
 All subsequent VREFDQ Calibration MR setting commands are MR6 [7:6] = 10 & MR6 [5:0] = VVVVVV
- {VVVVVV are desired settings for VREFDQ}
 Issue ACT/WR/RD looking for pass/fail to determine VCENT(midpoint) as needed
 Just prior to exiting VREFDQ Calibration mode:
 Last two VREFDQ Calibration MR commands are
 MR6 [7:6] = 10, MR6 [5:0] = VVVVVV’ where VVVVVV’ = desired value for VREFDQ
 MR6 [7] = 0, MR6 [6:0] = XXXXXXX to exit VREFDQ Calibration mode
Entering VREFDQ Calibration if entering range 2:
 MR6 [7:6] = 11 & [5:0] = XXXXXX
 All subsequent VREFDQ Calibration MR setting commands are MR6 [7:6]=11 & MR6 [5:0]=VVVVVV
- {VVVVVV are desired settings for VREFDQ}
 Issue ACT/WR/RD looking for pass/fail to determine VCENT(midpoint) as needed
 Just prior to exiting VREFDQ Calibration mode:
 Last two VREFDQ Calibration MR commands are
 MR6 [7:6] = 11, MR6 [5:0] = VVVVVV’ where VVVVVV’ = desired value for VREFDQ
 MR6 [7] = 0, MR6 [6:0] = XXXXXXX to exit VREFDQ Calibration mode
Stepsize VREF_val_tol
VREF
(VDDQ DC)
VREF
Voltage
Time
t1
Figure 48. VREF step single stepsize increment case
Stepsize
VREF_val_tol
VREF
(VDDQ DC)
VREF
Voltage
Time
t1
Figure 49. VREF step single stepsize decrement case
AS4C256M16D4
Confidential
- 63 of 201 -
Rev.1.0 Aug.2019