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RTC

Discussion in 'General Electronics' started by Amit Olkar, Jan 21, 2004.

  1. Amit Olkar

    Amit Olkar Guest

    Why do RTCs have so much amount of memory on them (e.g. 512KBytes NV
    SRAM), when the actual data, which we read into our system (up,uc) is
    only in a few 10s of bytes.??? i am not getting the purpose of this
    memery and what is to be doen with it...
     
  2. dont know

    dont know Guest

    think of it as a memory with some extra functions
     
  3. Quark Ng

    Quark Ng Guest

    Yes, it is indeed memory w/ some extra functions. But it is more than
    that.

    Note that the RTC chip (probably) has a battery backup power input
    pin. Now when the main power is turned off, the rest of your system
    will be effectively dead and any volatile memory in your system that
    relies on that main power will develop amnesia.

    But if you had something you want to keep in memory even after the
    power is off, save it to the RTC chip's memory. The battery backup
    will make sure the RTC chip does not develop amnesia.

    Now, you will probably be asking... "Why not just use a Flash Memory
    for this?". If you look at the datasheet for Flash Memory chips, they
    will usually state that it has a life of 100,000 erase cycles AND you
    have to erase a whole block at a time. If you want to write to
    memory, say every second, then you will very quickly use up the life
    of your Flash Memory.

    The memory in the RTC chip solves several problems. It is effectivly
    a nonvolatile SRAM when the battery backup is availible. It can be
    written to for almost an infinite number of times. You do not have to
    erase a whole block (typically about 16Kbytes or more) at a time.

    I hope this helps. By the way, you may be interested in reading about
    FRAM chips. Try www.ramtron.com

    Best Regards,
    Quark
     
  4. Amit Olkar

    Amit Olkar Guest

    Thanks Quark this really helps a lot, i was really wondering about
    this memory on the RTC i have (its actually 512 KBytes, but now i know
    what all can be achieved. i can probably save a quarter of my onchip
    RAM in it now. thanks..
    Amit
     
  5. Robert Baer

    Robert Baer Guest

    ....as well as store some nice virii...
     
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