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IS42S86400D Datasheet(PDF) 8 Page - Integrated Silicon Solution, Inc |
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IS42S86400D Datasheet(HTML) 8 Page - Integrated Silicon Solution, Inc |
8 / 66 page 8 Integrated Silicon Solution, Inc. — www.issi.com Rev. A 08/29/2012 IS42/45R86400D/16320D/32160D, IS42/45S86400D/16320D/32160D GENERAL DESCRIPTION READ The READ command selects the bank from BA0, BA1 inputs and starts a burst read access to an active row. InputsA0-An(Forcolumnaddresses,n=A8forx32,n=A9 forx16,n=A11forx8),providesthestartingcolumnloca- tion.WhenA10isHIGH,thiscommandfunctionsasan AUTOPRECHARGEcommand.Whentheautoprecharge is selected, the row being accessed will be precharged at theendoftheREADburst.Therowwillremainopenfor subsequentaccesseswhenAUTOPRECHARGEisnot selected. DQ’s read data is subject to the logic level on the DQM inputs two clocks earlier. When a given DQM signalwasregisteredHIGH,thecorrespondingDQ’swill be High-Z two clocks later. DQ’s will provide valid data whentheDQMsignalwasregisteredLOW. WRITE A burst write access to an active row is initiated with the WRITEcommand.BA0,BA1inputsselectsthebank,and the starting column location is provided by inputs A0-An (Forcolumnaddresses,n=A8forx32,n=A9forx16,n=A11 forx8).AUTO-PRECHARGEisdeterminedbyA10. Therowbeingaccessedwillbeprechargedattheendof theWRITEburst,ifAUTOPRECHARGEisselected.If AUTOPRECHARGEisnotselected,therowwillremain open for subsequent accesses. A memory array is written with corresponding input data on DQ’s and DQM input logic level appearing at the same time. Data will be written to memory when DQM signal is LOW.WhenDQMisHIGH,thecorrespondingdatainputs willbeignored,andaWRITEwillnotbeexecutedtothat byte/column location. PRECHARGE The PRECHARGE command is used to deactivate the open row in a particular bank or the open row in all banks. BA0,BA1canbeusedtoselectwhichbankisprecharged or they are treated as “Don’t Care”. A10 determined whether one or all banks are precharged. After execut- ing this command, the next command for the selected bank(s) is executed after passage of the period t RP, which istheperiodrequiredforbankprecharging.Onceabank has been precharged, it is in the idle state and must be activatedpriortoanyREADorWRITEcommandsbeing issued to that bank. AUTO PRECHARGE TheAUTOPRECHARGEfunctionensuresthatthepre- charge is initiated at the earliest valid stage within a burst. Thisfunctionallowsforindividual-bankprechargewithout requiringanexplicitcommand.A10toenabletheAUTO PRECHARGEfunctioninconjunctionwithaspecificREAD orWRITEcommand.ForeachindividualREADorWRITE command, auto precharge is either enabled or disabled. AUTOPRECHARGEdoesnotapplyexceptinfull-page burst mode. Upon completion of the READ or WRITE burst, a precharge of the bank/row that is addressed is automatically performed. AUTO REFRESH COMMAND ThiscommandexecutestheAUTOREFRESHoperation. Therowaddressandbanktoberefreshedareautomati- callygeneratedduringthisoperation. Thestipulatedperiod (trc) is required for a single refresh operation, and no othercommandscanbeexecutedduringthisperiod. This commandisexecutedatleast8192timesforeveryTref period.DuringanAUTOREFRESHcommand,address bitsare“Don’tCare”.ThiscommandcorrespondstoCBR Auto-refresh. BURST TERMINATE The BURSTTERMINATE command forcibly terminates the burst read and write operations by truncating either fixed-length or full-page bursts and the most recently registeredREADorWRITEcommandpriortotheBURST TERMINATE. COMMAND INHIBIT COMMANDINHIBITpreventsnewcommandsfrombeing executed.Operationsinprogressarenotaffected,apart fromwhethertheCLKsignalisenabled NO OPERATION When CSislow,theNOPcommandpreventsunwanted commands from being registered during idle or wait states. LOAD MODE REGISTER DuringtheLOADMODEREGISTERcommandthemode registerisloadedfromA0-A12.Thiscommandcanonly be issued when all banks are idle. ACTIVE COMMAND When the ACTIVE COMMAND is activated, BA0, BA1 inputs selects a bank to be accessed, and the address inputsonA0-A12selectstherow.UntilaPRECHARGE command is issued to the bank, the row remains open for accesses. |
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