W632GU6NB
Publication Release Date: Aug. 20, 2018
Revision: A01
- 76 -
8.17.2 Power-Down clarifications - Case 1
When CKE is registered low for power-down entry, t
PD
(min) must be satisfied before CKE can be
registered high for power-down exit. The minimum value of parameter t
PD
(min) is equal to the
minimum value of parameter t
CKE
(min) as shown in section 10.16
on page 139.
A detailed example of Case 1 is shown in Figure 69.
T0
T1
T2
Ta0
Tb0
Tb1
Tb2
CK#
CK
VALID
NOP
NOP
t
IS
Ta1
NOP
NOP
NOP
VALID
VALID
t
IH
t
IH
t
IS
t
CPDED
t
CKE
t
CPDED
Enter
Power-Down
Mode
Exit
Power-Down
Mode
t
PD
Command
CKE
Address
TIME BREAK
DON'T CARE
t
IS
Enter
Power-Down
Mode
Figure 69
– Power-Down Entry/Exit Clarifications - Case 1
8.17.3 Power-Down clarifications - Case 2
For certain CKE intensive operations, for example, repeated ‘PD Exit - Refresh - PD Entry’ sequences,
the number of clock cycles between PD Exit and PD Entry may be insufficient to keep the DLL
updated. Therefore, the following conditions must be met in addition to t
CKE
in order to maintain
proper DRAM operation when the Refresh command is issued between PD Exit and PD Entry. Power-
down mode can be used in conjunction with the Refresh command if the following conditions are met:
1) t
XP
must be satisfied before issuing the command.
2) t
XPDLL
must be satisfied (referenced to the registration of PD Exit) before the next power-down can
be entered. A detailed example of Case 2 is shown in Figure 70.
T0
T1
T2
Ta1
CK#
CK
VALID
NOP
Tb0
NOP
NOP
NOP
t
XPDLL
Command
NOP
Ta0
CKE
Tb1
Tc0
REF
Address
VALID
t
CPDED
Exit
Power-Down
Mode
Enter
Power-Down
Mode
t
IH
t
IS
t
IH
t
IS
t
PD
Tc1
Td0
NOP
NOP
t
XP
t
CKE
Enter
Power-Down
Mode
TIME BREAK
DON'T CARE
Figure 70
– Power-Down Entry/Exit Clarifications - Case 2