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Looking for a replacement sram dip chip.

Discussion in 'Datasheets, Manuals and Component Identification' started by wilsoe, Aug 27, 2014.

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  1. wilsoe

    wilsoe

    19
    0
    Jul 28, 2010
    I am looking for a replacement part for a sram chip. I have a couple of the same devices and the following are different chips used in the product. They are placed on top of a Dallas DS1216.
    • IS62C64-70W
    • LH516A-10L
    • V62C51864L-70P
    I can find sram chips that are 8k x 8, 8,192 word, 24 pins and 5 volts.... But how can I find a compatible chip..... or a replacement?
    Thanks for any help
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,220
    2,201
    Nov 17, 2011
    You'll haev to compare the datasheets of the potential replacement chips with the original ones, especially the timings.
    -70W and -70P hin at the original chips being classified as 70ns access time types. The LH516A-10L is a 80ns/100ns type (datasheet).

    Your chances are good that any 70ns 8kx8 SRAM chip with matching pinout will work as these used to be rather well standardized.
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Count the pins again. I think you'll find it's 28 pins.

    Get a datasheet, then go to a place like digikey and search for 8k x 8 static ram in 28 pin pdip packages. Then check their datasheets to make sure they have the same pinout.

    You'll probably find that at least some of the part numberss will have similarities to the ones you have.

    Also ensure you select 70ns or faster devices. (edit, or 100ns and faster -- thanks Harald)

    I've done most of that for you here.
     
  4. wilsoe

    wilsoe

    19
    0
    Jul 28, 2010
    Thanks Harald and Steve..... Just to clarify. The Sharp chip is a LH5164A-10L like the link Harald added.... I had to update my notes thanks! Also Steve you are correct.... everything is 28 pins. I messed up on both points.

    I did find all the datasheets and looked at them forever..... Believe it or not. :) I just do not understand how to compare or find a new chip..... Does the "Read Cycle" and "Write Cycle" matter? I can found a chip that has the same pin outs.... but the "Switching Characteristics" and the "Waves" or "Cycles" always seem a little different.

    I do like Harald's advice and I will purchase some 70ns chips with the same pin outs.... from the chips you suggested Steve!
    Thanks like always!
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The most important thing is that:
    • The pins are all listed as having the same functions
    • The "headline" features are the same (are they both (say) synchronous?)
    It is unlikely that the wrong chip will break anything, it will most likely just not work.
     
  6. wilsoe

    wilsoe

    19
    0
    Jul 28, 2010
    I will give it a shot and not worry with the cycle charts and see what happens. Seem like the only chip you suggested that was in stock and is 70ns has the same pin functions and all notable features? Or at least I think so and will try it out! :)
    Thanks again for the help!
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    If you want to post the part you've chosen I can give it a quick look and see if it looks Ok to me too.
     
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