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4Mx32 DDR SDRAM

EM6A9320

Etron Confidential

4

Rev 0.3

July. 2002

Pin Descriptions

Table 1. Pin Details of EM6A9320

Symbol

Type

Description

CK, CK#

Input

Differential Clock: CK, CK# are driven by the system clock. All SDRAM input

commands are sampled on the positive edge of CK. Both CK and CK# increment the

internal burst counter and controls the output registers.

CKE

Input

Clock Enable: CKE activates (HIGH) and deactivates (LOW) the CK signal. If CKE

goes low synchronously with clock, the internal clock is suspended from the next clock

cycle and the state of output and burst address is frozen as long as the CKE remains

low. When all banks are in the idle state, deactivating the clock controls the entry to

the Power Down and Self Refresh modes.

BA0, BA1

Input

Bank Select: BA0 and BA1 defines to which bank the BankActivate, Read, Write, or

BankPrecharge command is being applied. They also define which Mode Register or

Extended Mode Register is loaded during a Mode Register Set command.

A0-A11

Input

Address Inputs: A0-A11 are sampled during the Bank Activate command (row

address A0-A11) and Read/Write command (column address A0-A7 with A8 defining

Auto Precharge) to select one location out of the 256K available in the respective

bank. During a Precharge command, A8 is sampled to determine if all banks are to be

precharged (A8 = HIGH). The address inputs also provide the op-code during a Mode

Register Set or Extended Mode Register Set command.

CS#

Input

Chip Select: CS# enables (sampled LOW) and disables (sampled HIGH) the

command decoder. All commands are masked when CS# is sampled HIGH. CS#

provides for external bank selection on systems with multiple banks. It is considered

part of the command code.

RAS#

Input

Row Address Strobe: The RAS# signal defines the operation commands in

conjunction with the CAS# and WE# signals and is latched at the positive edges of

CK. When RAS# and CS# are asserted "LOW" and CAS# is asserted "HIGH" either

the BankActivate command or the Precharge command is selected by the WE# signal.

When the WE# is asserted "HIGH," the BankActivate command is selected and the

bank designated by BS is turned on to the active state. When the WE# is asserted

"LOW," the Precharge command is selected and the bank designated by BS is

switched to the idle state after the precharge operation.

CAS#

Input

Column Address Strobe: The CAS# signal defines the operation commands in

conjunction with the RAS# and WE# signals and is latched at the positive edges of

CK. When RAS# is held "HIGH" and CS# is asserted "LOW" the column access is

started by asserting CAS# "LOW" Then, the Read or Write command is selected by

asserting WE# "HIGH " or “LOW".

WE#

Input

Write Enable: The WE# signal defines the operation commands in conjunction with

the RAS# and CAS# signals and is latched at the positive edges of CK. The WE#

input is used to select the BankActivate or Precharge command and Read or Write

command.

DQS0-DQS3

Input /

Output

Bidirectional Data Strobe: The DQSx signals are mapped to the following data

bytes: DQS0 to DQ0-DQ7, DQS1 to DQ8-DQ15, DQS2 to DQ16-DQ23, DQS3 to

DQ24-DQ31.

DM0 - DM3

Input

Data Input Mask: DM0-DM3 are byte specific. Input data is masked when DM is

sampled HIGH during a write cycle. DM3 masks DQ31-DQ24, DM2 masks DQ23-

DQ16, DM1 masks DQ15-DQ8, and DM0 masks DQ7-DQ0.

DQ0 - DQ31

Input /

Output

Data I/O: The DQ0-DQ31 input and output data are synchronized with the positive

edges of CK and CK#. The I/Os are byte-maskable during Writes.

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