IS43DR32800A-37CBLI ISSI, IS43DR32800A-37CBLI Datasheet - Page 38

• Manufacturer Part Number: IS43DR32800A-37CBLI
• Description: DRAM 256M (8Mx32) 266MHz Industrial Temp
• Manufacturer: ISSI

Specifications of IS43DR32800A-37CBLI

• Product Category: DRAM
• Rohs: yes
• Factory Pack Quantity: 162

IS43DR32800A, IS43/46DR32801A
PREChARGE
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 a specified time (tRP) after the PRECHARGE command
is issued, except in 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 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 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.
REFRESh
REFRESH is used during normal operation of the DDR2 SDRAM and is analogous to CAS-before-RAS (CBR)
REFRESH. All banks must be in the idle mode prior to issuing a REFRESH command. This command is
nonpersistent, so it must be issued each time a refresh is required. The addressing is generated by the internal refresh
controller. This makes the address bits a “Don’t Care” during a REFRESH command.
SELF REFRESh
The SELF REFRESH command can be used to retain data in the DDR2 SDRAM, even if the rest of the system is
powered down. When in the self refresh mode, the DDR2 SDRAM retains data without external clocking. All power
supply inputs (including VREF) must be maintained at valid levels upon entry/exit and during SELF REFRESH
operation.
The SELF REFRESH command is initiated like a REFRESH command except CKE is LOW. The DLL is automatically
disabled upon entering self refresh and is automatically enabled upon exiting self refresh.
ODT (On-Die Termination)
The On-Die Termination feature allows the DDR2 SDRAM to easily implement a termination resistance (Rtt) for
each DQ, DQS, and DQS signal. The ODT feature can be configured with the Extended Mode Register Set (EMRS)
command, and turned on or off using the ODT input signal. Before and after the EMRS is issued, the ODT input
must be received with respect to the timings of tAOFD, tMOD(max), tAOND; and the CKE input must be held HIGH
throughout the duration of tMOD(max).
The DDR2 SDRAM supports the ODT on and off functionality in Active, Standby, and Power Down modes, but not in
Self Refresh mode. ODT timing diagrams follow for Active/Standby mode and Power Down mode.
EMRS to ODT Update Delay
38
ODT
CMD
Rtt
CK
CK
tAOFD
Old setting
E MRS
tMOD,min
NOP
tMOD,max
NOP
NOP
Integrated Silicon Solution, Inc. — www.issi.com
ODT Ready
NOP
tIS
tAOND
NOP
Updated
09/08/2010
Rev. 00E