Rev. 1.2 Aug. 2005

512MB, 1GB, 2GB Registered DIMMs

DDR2 SDRAM

Input/Output Functional Description

Symbol

Type

Function

CK0

Input

Positive line of the differential pair of system clock inputs that drives input to the on-DIMM PLL.

CK0

Input

Negative line of the differential pair of system clock inputs that drives the input to the on-DIMM PLL.

CKE0~CKE1

Input

Activates the 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 Refresh mode.

S0~S1

Input

Enables the associated SDRAM command decoder when low and disables decoder when high. When decoder is disabled,

new commands are ignored but previous operations continue.

These input signals also disable all outputs (except CKE and ODT) of the register(s) on the DIMM when both inputs are

high.

ODT0~ODT1

Input

I/O bus impedance control signals.

RAS, CAS, WE

Input

When sampled at the positive rising edge of the clock, CAS, RAS, and WE define the operation to be executed by the

SDRAM.

Supply

Reference voltage for SSTL_18 inputs

Supply

Isolated power supply for the DDR SDRAM output buffers to provide improved noise immunity

BA0~BA1

Input

Selects which SDRAM bank of four is activated.

A0~A9,A10/AP

A11~A13

Input

During a Bank Activate command cycle, Address defines the row address.

During a Read or Write command cycle, Address defines the column address. In addition to the column address, AP is

used to invoke autoprecharge operation at the end of the burst read or write cycle. If AP is high, autoprecharge is selected

and BA0, BA1 defines the bank to be precharged. If AP is low, autoprecharge is disabled. During a Precharge command

cycle, AP is used in conjunction with BA0, BA1 to control which bank(s) to precharge. If AP is high, all banks will be pre-

charged regardless of the state of BA0 or BA1. If AP is low, BA0 and BA1 are used to define which bank to precharge.

DQ0~63,

CB0~CB7

In/Out

Data and Check Bit Input/Output pins

DM0~DM8

Input

Masks write data when high, issued concurrently with input data. Both DM and DQ have a write latency of one clock once

the write command is registered into the SDRAM.

Supply

Power and ground for the DDR SDRAM input buffers and core logic

DQS0~DQS17

In/Out

Positive line of the differential data strobe for input and output data.

DQS0~DQS17

In/Out

Negative line of the differential data strobe for input and output data.

SA0~SA2

Input

SDA

In/Out

This bidirectional pin is used to transfer data into or out of the SPD EEPROM. A resistor must be connected from the SDA

SCL

Input

This signal is used to clock data into and out of the SPD EEPROM. A resistor may be connected from the SCL bus time

Supply

Serial EEPROM positive power supply (wired to a separate power pin at the connector which supports from 1.7 Volt to 3.6

Volt operation).

RESET

Input

The RESET pin is connected to the RST pin on the register and to the OE pin on the PLL. When low, all register outputs

will be driven low and the PLL clocks to the DRAMs and register(s) will be set to low level (The PLL will remain synchro-

nized with the input clock )

Par_In

Input

Parity bit for the Address and Control bus. ( “1 “ : Odd, “0 “ : Even)

Err_Out

Input

Parity error found in the Address and Control bus

TEST

In/Out

Used by memory bus analysis tools (unused on memory DIMMs)