Rev. 1.3 Aug. 2005

256MB, 512MB Unbuffered DIMMs

DDR2 SDRAM

Input/Output Functional Description

Symbol

Type

Function

CK0-CK2

CK0-CK2

Input

CK and CK are differential clock inputs. All the SDRAM addr/cntl inputs are sampled on the crossing of positive edge of

CK and negative edge of CK. Output (read) data is reference to the crossing of CK and CK (Both directions of crossing)

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 Powe Down mode, or the Self-Refresh mode

S0-S1

Input

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

command decoder is disbled, new command are ignored but previous operations continue. This signal provides for exter-

nal rank selection on systems with multiple ranks

RAS, CAS, WE

Input

ODT0-ODT1

Input

When high, termination resistance is enabled for all DQ, DQ and DM pins, assuming the function is enabled in the

Extended Mode Register Set (EMRS).

Supply

Reference voltage for SSTL 18 inputs.

Supply

Power supply for the DDR II SDRAM output buffers to provide improved noise immunity. For all current DDR2 unbuffered

DIMM designs, VDDQ shares the same power plane as VDD pins.

BA0-BA1

Input

Selects which SDRAM BANK of four is activated.

A0-A13

Input

During a Bank Activate command cycle, Address input defines the row address (RA0-RA13)

During a Read or Write command cycle, Address input defines the colum 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 disbled. 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 precharged regardless of the state of BA0, BA1. If AP is low, BA0, BA1are used to define which bank to pre-

charge.

DQ0-DQ63

CB0-CB7

In/Out

Data and Check Bit Input/Output pins.

DM0-DM8

Input

DM is an input mask signal for write data. Input data is masked when DM is sampled High coincident with that input data

during a write access. DM is sampled on both edges of DQS. Although DM pins are input only, the DM loading matches

the DQ and DQS loading.

Supply

these modules.

DQS0-DQS8

DQS0-DQS8

In/Out

Data strobe for input and output data. For Rawcards using x16 orginized DRAMs DQ0-7 connect to the LDQS pin of the

DRAMs and DQ8-17 connect to the UDQS pin of the DRAM

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 bus line to VDD to act as a pullup on the system board.

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

to VDD to act as a pullup onthe system board.

Supply

from 1.7V to 3.6V.