IBM0316809C IBM0316409C
IBM0316169C
16Mbit Synchronous DRAM
No Operation Command
The No Operation Command should be used in cases when the SDRAM is in a idle or a wait state. The pur-
pose of the No Operation Command is to prevent the SDRAM from registering any unwanted commands
between operations. A No Operation Command is registered when CS is low with RAS, CAS, and WE held
high at the rising edge of the clock. A No Operation Command will not terminate a previous operation that is
still executing, such as a burst read or write cycle.
Deselect Command
The Deselect Command performs the same function as a No Operation Command. Deselect Command
occurs when CS is brought high, the RAS, CAS, and WE signals become don’t cares.
Power Down Mode
In order to reduce standby power consumption, a power down mode is available. All banks must be pre-
charged and the necessary Precharge delay (tRP) must occur before the SDRAM can enter the Power Down
mode. Once the Power Down mode is initiated by holding CKE low, all of the receiver circuits except CLK and
CKE are gated off. The Power Down mode does not perform any refresh operations, therefore the device
can’t remain in Power Down mode longer than the Refresh period (tREF) of the device.
The Power Down mode is exited by bringing CKE high. A one clock delay after the registration of CKE high is
required for the SDRAM to exit the Power Down mode.
©IBM Corporation, 1996. All rights reserved.
Use is further subject to the provisions at the end of this document.
07H3997
SA14-4711-02
Revised 05/96
Page 22 of 100
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