Data Sheet
HY[B/E]18M1G16[0/1]BF
1-Gbit DDR Mobile-RAM
2.4.8
PRECHARGE
The PRECHARGE command is used to deactivate (close) the
open row in a particular bank or the open rows in all banks.
The bank(s) will be available for a subsequent row access a
specified time (tRP) after the PRECHARGE command is
issued. Input A10 determines whether one or all banks are to
be precharged, and in the case where only one bank is to be
precharged, inputs BA0, BA1 select the bank. Otherwise
BA0, BA1 are treated as “Don’t Care.”
FIGURE 32
PRECHARGE Command
CK
CK
CKE
(High)
Once a bank has been 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 will be
treated as a NOP if there is no open row in that bank, or if the
previously open row is already in the process of precharging.
CS
RAS
CAS
WE
A0-A9
A11,A12
All Banks
A10
One Bank
BA
BA0,BA1
= Don't Care
BA = Bank Address
(if A10 = L, otherwise Don't Care)
TABLE 13
Timing Parameters for PRECHARGE Command
Parameter
Symbol
- 6
- 7.5
Unit
Note
min.
42
max.
min.
max.
70,000 ns
1)
1)
1)
ACTIVE to PRECHARGE command period
PRECHARGE command period
WRITE recovery time
tRAS
tRP
70,000 45
18
15
–
–
22.5
15
–
–
ns
ns
tWR
1) These parameters account for the number of clock cycles and depend on the operating frequency, as follows:
no. of clock cycles = specified delay / clock period; round to the next higher integer.
Rev.1.0, 2007-03
41
10242006-Y557-TZXW
QIMONDA [ QIMONDA AG ]
