EM6A9320_06 参数 Datasheet PDF下载

EtronTech

4Mx32 DDR SDRAM

EM6A9320

Extended Mode Register Set (EMRS)

The Extended Mode Register Set stores the data for enabling or disabling DLL and selecting output driver

strength. The default value of the extended mode register is not defined, therefore must be written after power

up for proper operation. The extended mode register is written by asserting low on CS#, RAS#, CAS#, and

WE#. The state of A0, A2 ~ A5, A7 ~ A11and BA1 is written in the mode register in the same cycle as CS#,

RAS#, CAS#, and WE# going low. The DDR SDRAM should be in all bank precharge with CKE already high

prior to writing into the extended mode register. A1 and A6 are used for setting driver strength to normal, weak

or matched impedance. Two clock cycles are required to complete the write operation in the extended mode

register. The mode register contents can be changed using the same command and clock cycle requirements

during operation as long as all banks are in the idle state. A0 is used for DLL enable or disable. "High" on BA0

is used for EMRS. Refer to the table for specific codes.

Extended Mode Resistor Bitmap

BA1

0

BA0

1

A11

A10

A9

A8

RFU must be set to “0”

A7

A6

DS1

A5

A4

A3

A2

RFU must be set to “0”

A1

DS0

A0

DLL

BA0 Mode

0

MRS

1 EMRS

A6

0

0

1

1

A1

Drive Strength

Strength

Comment

0

Full

100%

1

SSTL-2 weak

60%

0

RFU

RFU Do not use

1 Matched impedance 30%

Output driver matches impedance

A0

DLL

0

Enable

1 Disable

Power up Sequence

Power up must be performed in the following sequence.

1) Apply power to V

DD

before or at the same time as V

DDQ,

V

TT

and V

REF

when all input signals are held

"NOP" state and maintain CKE “LOW”.

2) Start clock and maintain stable condition for minimum 200us.

3) Issue a “NOP” command and keep CKE “HIGH”

4) Issue a “Precharge All” command.

5) Issue EMRS – enable DLL.

6) Issue MRS – reset DLL. (An additional 200 clock cycles are required to lock the DLL).

7) Precharge all banks of the device.

8) Issue two or more Auto Refresh commands.

9) Issue MRS – with A8 to low to initialize the mode register.

7

Rev 0.6

May. 2006