W641GG2JB Datasheet, PDF(55/109 Page) Winbond – 1-Gbit GDDR3 Graphics SDRAM

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W641GG2JB Datasheet, PDF (55/109 Pages) Winbond – 1-Gbit GDDR3 Graphics SDRAM

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W641GG2JB

6.11.2 Bank Activation Timing

CLK#

CLK

Com. ACT

R/W

A0-A11 Row

Col

BA0,BA1 B.Y

B.Y

tRCD

tRAS

PRE

B.Y

tRC

1-Gbit GDDR3 Graphics SDRAM

ACT

Row

B.Y

ACT

Row

B.X

tRRD

Row: Row Address

Col: Column Address

B.X: Bank X

B.Y: Bank Y

R/W: READ or WRITE command

PRE: PRECHARGE command

ACT: ACTIVATE command

Donât care

6.11.3 Bank Activation Timing on different rank in 2-CS mode

CLK#

CLK

Com. ACT

R/W

PRE

A0-A11 Row

Col

BA0,BA1 B.Y

B.Y

tRCD

tRAS

B.Y

tRC

ACT_0

Row

B.Y

ACT_1

Row

B.X

tRRD_RR=1

Row: Row Address

Col: Column Address

B.X: Bank X

B.Y: Bank Y

R/W: READ or WRITE command

PRE: PRECHARGE command

ACT_0: ACTIVATE command Rank 0

ACT_1: ACTIVATE command Rank 1

Donât care

For eight bank GDDR3 devices, there may be a need to limit the number of activates in a rolling window to ensure that the

instantaneous current supplying capability of the devices is not exceeded. To reflect the true capability of the DRAM instantaneous

current supply, the parameter tFAW (four activate window) is defined. No more than 4 banks may be activated in a rolling tFAW

window. Converting to clocks is done by dividing tFAW (ns) by tCK (ns) and rounding up the next integer value. As an example of the

rolling window, if (tFAW / tCK) rounds up to 10 clocks, and an activate command is issued in clock n, no more than three further

activate commands may be issued in clocks n+1 through n+9. tFAW is only valid within one rank. There is no further restriction

between ranks.

6.11.4 Four Window Active tFAW

CLK#

CLK

CMD

ACT

tRRD

ACT

tRRD

tFAW

tFAW+3*tRRD

ACT:ACTIVATE command

Donât care

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Publication Release Date: Apr, 22, 2011

Revision A01-002

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