Rev. 1.2 Aug. 2005

256MB, 512MB, 1GB Unbuffered SODIMMs

DDR2 SDRAM

Input/Output Functional Description

Symbol

Type

Function

CK0-CK1

CK0-CK1

Input

The system clock inputs. All address and command lines are sampled on the cross point of the rising edge of CK and fall-

ing edge of CK . A Delay Locked Loop (DLL) circuit is driven from the clock input and output timing for read operations is

synchronized to the input clock.

CKE0-CKE1

Input

Activates the DDR2 SDRAM CK signal when high and deactivates the CK signal when low, By deactivating the clocks,

CKE low initiates the Power Down mode or the Self Refesh mode.

S0-S1

Input

Enables the associated DDR2 SDRAM command decoder when low and disables the command decoder when high.

When the command decoder is disabled, new commands are ignored but previous operations continue. Rank 0 is selected

by S0, Rank 1 is selected by S1. Ranks are also called “Physical banks”.

RAS, CAS, WE

Input

When sampled at the cross point of the rising edge of CK and falling edge of CK, CAS, RAS, and WE define the operation

to be executed by the SDRAM.

BA0~BA1

Input

Selects which DDR2 SDRAM internal bank is activated.

ODT0~ODT1

Input

Asserts on-die termination for DQ, DM, DQS, and DQS signals if enabled via the DDR2 SDRAM Extended Mode Register

Set (EMRS).

A0~A9,

A10/AP,

A11~A13

Input

During a Bank Activate command cycle, defines the row address when sampled at the cross point of the rising edge of CK

and falling edge of CK. During a Read or Write command cycle, defines the column address when sampled at the cross

point of the rising edge of CK and falling edge of CK. In addition to the column address, AP is used to invoke autopre-

charge operation at the end of the burst read or write cycle. If AP is high, autoprecharge is selected and BA0-BAn defines

the bank to be precharged. If AP is low, autoprecharge is disabled. During a Precharge command cycle, AP is used in con-

junction with BA0-BAn to control which bank(s) to precharge. If AP is high, all banks will be pecharged regardiess of the

state of BA0-BAn inputs. If AP is low, then BA0-BAn are used to define which bank to precharge.

DQ0~DQ63

In/Out

Data Input/Output pins.

DM0~DM7

Input

The data write masks, associated with one data byte. In Write mode, DM operates as a byte mask by allowing input data to

be written if it is low but blocks the write operation if it is high. In Read mode, DM lines have no effect.

DQS0~DQS7

DQS0~DQS7

In/Out

The data strobes, associated with one data byte, sourced with data transfers. In Write mode, the data strobe is sourced by

the controller and is centered in the data window. In Read mode, the data strobe is sourced by the DDR2 SDRAMs and is

sent at the leading edge of the data window. DQS signals are complements, and timing is relative to the crosspoint of

respective DQS and DQS If the module is to be operated in single ended strobe mode, all DQS signals must be tied on the

system board to VSS and DDR2 SDRAM mode registers programmed appropriately.

Supply

Power supplies for core, I/O, Serial Presence Detect, and ground for the module.

SDA

In/Out

as a pull up.

SCL

Input

a pull up.

SA0~SA1

Input

Address pins used to select the Serial Presence Detect base address.

TEST

In/Out

The TEST pin is reserved for bus analysis tools and is not connected on normal memory modules(SO-DIMMs).