IS43LD16640C datasheet(56/142 Pages) ISSI

56 / 142 page

IS43/46LD16640C

IS43/46LD32320C

Integrated Silicon Solution, Inc. — www.issi.com

Rev. C

07/02/2021

® Long-term Support

World Class Quality

An all-bank REFRESH command (REFab) issues a REFRESH command to all banks. All banks

must be idle when REFab is issued (for instance, by issuing a PRECHARGE ALL command prior

to issuing an all-bank REFRESH command). REFab also synchronizes the bank count between

the controller and the SDRAM to zero. The REFab command must not be issued to the device until

the following conditions have been met:

• tRFCab has been satisfied following the prior REFab command

• tRFCpb has been satisfied following the prior REFpb command

• tRP has been satisfied following the prior PRECHARGE commands

After an all-bank REFRESH cycle has completed, all banks will be idle. After issuing REFab:

• tRFCab latency must be satisfied before issuing an ACTIVATE command

• tRFCab latency must be satisfied before issuing a REFab or REFpb command

REFRESH Command Scheduling Separation Requirements

Command Scheduling Separations related to Refresh

Symbol

minimum delay fromtoNotes

REFab

Activate cmd to any bank .

REFpb

REFab

Activate cmd to same bank as REFpb

REFpb

Activate cmd to different bank than REFpb

REFpb affecting an idle bank (different bank than Activate)

Activate cmd to different bank than prior Activate

REFab

tRFCab

tRFCpb

REFpb

tRRD

Activate

Note: A bank must be in the idle state before it is refreshed, so REFab is prohibited following an ACTIVATE command. REFpb is

supported only if it affects a bank that is in the idle state.

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