MT40A512M8RH-083E Datasheet, PDF (139/365 Pages) Micron Technology – Programmable data strobe preambles

4Gb: x4, x8, x16 DDR4 SDRAM
PRECHARGE Command
ent bank groups (five ACTIVATE commands issued at ^tRRD_L (MIN) to the same bank
group would be limited by ^tRC).
Figure 78: ^tRRD Timing
CK_c
T0
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
CK_t
Command
ACT
DES
DES
DES
ACT
DES
DES
DES
DES
DES
ACT
DES
t_{RRD_S}
t_{RRD_L}
Bank
Group BG a
BG b
(BG)
BG b
Bank Bank c
Bank c
Bank d
Address Row n
Row n
Row n
Don’t Care
Notes:
1. ^tRRD_S; ACTIVATE-to-ACTIVATE command period (short); applies to consecutive ACTI-
VATE commands to different bank groups (that is, T0 and T4).
2. ^tRRD_L; ACTIVATE-to-ACTIVATE command period (long); applies to consecutive ACTI-
VATE commands to the different banks in the same bank group (that is, T4 and T10).
Figure 79: ^tFAW Timing
CK_c
T0
CK_t
Ta0
Tb0
Tc0
Tc1
Tc2
Td0
Td1
Command
ACT
Valid
ACT
Valid
ACT
Valid
ACT
Valid
Valid
Valid
ACT
NOP
Bank
Group
(BG)
Valid
t_RRD
Valid
t_RRD
Valid
t_RRD
Valid
t_FAW
Valid
Bank
Valid
Valid
Valid
Valid
Valid
Address
Valid
Valid
Valid
Valid
Valid
Note: 1. ^tFAW; four activate windows.
Don’t Care
Time Break
PRECHARGE Command
The PRECHARGE command is used to deactivate the open row in a particular bank or
the open row in all banks. The bank(s) will be available for a subsequent row activation
for a specified time (^tRP) after the PRECHARGE command is issued. An exception to
this is the case of concurrent auto precharge, where a READ or WRITE command to a
different bank is allowed as long as it does not interrupt the data transfer in the current
bank and does not violate any other timing parameters.
After a bank is precharged, it is in the idle state and must be activated prior to any READ
or WRITE commands being issued to that bank. A PRECHARGE command is allowed if
there is no open row in that bank (idle state) or if the previously open row is already in
the process of precharging. However, the precharge period will be determined by the
last PRECHARGE command issued to the bank.
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4gb_ddr4_dram.pdf - Rev. G 1/17 EN
139
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