A43E06161_15 Datasheet, PDF(14/48 Page) AMIC Technology – 512K X 16 Bit X 2 Banks Synchronous DRAM

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A43E06161_15 Datasheet, PDF (14/48 Pages) AMIC Technology – 512K X 16 Bit X 2 Banks Synchronous DRAM

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A43E06161

by âtRC(min)â. The minimum number of clock cycles required

can be calculated by driving âtRCâ with clock cycle time and

then rounding up to the next higher integer. The auto refresh

command must be followed by NOPâs until the auto refresh

operation is completed. Both banks will be in the idle state at

the end of auto refresh operation. The auto refresh is the

preferred refresh mode when the SDRAM is being used for

normal data transactions. The auto refresh cycle can be

performed once in 15.6us or a burst of 2048 auto refresh

cycles once in 32ms.

Self Refresh

The self refresh is another refresh mode available in the

SDRAM. The self refresh is the preferred refresh mode for

data retention and low power operation of SDRAM. In self

refresh mode, the SDRAM disables the internal clock and all

the input buffers except CKE. The refresh addressing and

timing is internally generated to reduce power consumption.

The self refresh mode is entered from all banks idle state by

asserting low on CS , RAS , CAS and CKE with high on

WE . Once the self refresh mode is entered, only CKE state

being low matters, all the other inputs including clock are

ignored to remain in the self refresh.

The self refresh is exited by restarting the external clock and

then asserting high on CKE. This must be followed by NOPâs

for a minimum time of âtRCâ before the SDRAM reaches idle

state to begin normal operation. If the system uses burst auto

refresh during normal operation, it is recommended to used

burst 2048 auto refresh cycles immediately after exiting self

refresh.

Deep Power Down Mode

The Deep Power Down Mode is an unique function on Low

Power SDRAMs with very low standby currents. All internal

voltage generators inside the Low Power SDRAMs are

stopped and all memory data will be lost in this mode. To

enter the Deep Power Down Mode all banks must be

precharged and the necessary Precharged Delay tRP must

occur.

PRELIMINARY (February, 2008, Version 0.3)

AMIC Technology, Corp.

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