參數(shù)資料
        型號: HM628512LRR-7
        英文描述: x8 SRAM
        中文描述: x8的SRAM
        文件頁數(shù): 1/1頁
        文件大?。?/td> 60K
        代理商: HM628512LRR-7
        date: 2002/10/04
        1/1
        HITACHI SEMICONDUCTOR TECHNICAL UPDATE
        Classification
        of Production
        Memory
        No
        TN-M62-112A/E
        Rev
        1
        THEME
        SRAM: Notes on Usage
        Classification of
        Information
        1.
        2.
        3.
        4.
        5. Change of Production Line
        Spec change
        Supplement of Documents
        Limitation of Use
        Change of Mask
        Lot No.
        Effective Date
        PRODUCT
        NAME
        All 4-Mbit fast
        SRAM C-mask
        products
        All Lots
        Reference
        Documents
        Hitachi IC memory datasheets
        ADE-203-1196B(Z)/1198B(Z)/1199B(Z)/
        1200C(Z)/1294D(Z)/1202C(Z)/1263A(Z)
        /1283A(Z)/1304A(Z)/1305A(Z)
        Permanent
        As the operating speeds of SRAM products rise, securing the various design margins is becoming more
        difficult. Accordingly, there is an increasing possibility of noise from the input-signal or power-supply
        lines acting as an obstacle to the normal operation of SRAM products. To prevent malfunctions in 4-Mbit
        fast SRAM (C-mask) products, please note the following points.
        1.
        Announcement
        In executing a write-with-verify operations with a 4-Mbit fast SRAM (C-mask) product, incorrect data
        may be read because of noise, etc., even when the data has been written correctly (see figure 1 and note
        1). This problem does not arise with a further read operation. If you are having problems of the type
        described or your project may be subject to such problems, refer to the points below for the appropriate
        countermeasures.
        2.
        Countermeasures
        Please apply countermeasures (1) and (2) below according to your situation.
        (1)
        Avoid executing the read for verification in the same cycle as the write operation it follows. Verify the
        written data after inputting an address or switching the /CS signal.
        (2)
        Please ensure that your design is not subject to adverse effects because of distortion or skewing of the
        Din input waveform (figure 2). Drive /WE low (write) after determining the data on Din (see figure 3).
        Time
        Din waveform skew
        Figure 2 Din Input Waveform
        Distortion of input waveform
        Input threshold voltage
        *1:
        Write verify : After data is written within the same
        address cycle, perform data-read operation.
        Figure 1. Write Verify Timing
        ADD
        /CS
        /WE
        Din
        STRB
        Fixed to a low level
        /D
        D
        Read operation
        /OE
        /WE
        Din
        /D
        D
        After the Din data is
        determined, drive /WE low.
        Figure 3 Write Verify Timing (Countermeasure Applied)
        V
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