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altera question

Discussion in 'Electronic Design' started by [email protected], Mar 25, 2009.

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  1. Guest

    Hey gang,
    there are maybe better places to ask, but googling reveals very little
    on this topic.
    we are using a maxii cpld. I am not directly involved in the design of
    this part of the circuit, so i don't have much knowledge of the cpld
    the datasheet says max prog/erase cycles is 100.

    on page 61 of the datasheet

    what does the 100 cycles refer to? How are CPLDs programmed these
    days? What is in there exactly? RAM loaded by a flash on power up?

    (I stopped design back when a 22V10 was a current part...)
  2. StoneThrower

    StoneThrower Guest

    what does the 100 cycles refer to?
    Cycle is refered to a (one) program-erase cycle. (that is: you first program
    the chip with something, i.e. current design, then if you don't like it or
    you found a bug then you reuse the chip by erasing the chip and then you
    reprogram the chip again with the new content, and that is called a cycle).
    "100" is # of times you can erase/program chip before it fails to be
    reprogramed again, after that is being considered "burned" (broken, kaput,
    dead ...).
    With programmers (devices) generally refered to as "download cables"
    In there is a programmable field (actually quite similar to 22V10's
    interconnect field) containing "fuses" being "blown" during programming.
    That 'field' interconnects logical gates and flip-flops. They are not being
    blown, it's just a figurative speach/expression. These 'fuses' are made of
    MOSFET transitors with insulated pocket of metal intrenched above "Gate" of
    the MOSFET, forming a tiny capacitor. After programming that 'pocket' holds
    the charge causing tranisitor to be closed. Discharging the pocket
    ("erasing") causes transistor to be open.
  3. Guest

    Of what, the CPLD part or the UFM, etc?
    Hm, thanks, I meant more the mechanism inside that would deteriorate
    after 100 cycles.
    Thanks, what would the symptoms be when we start to exceed 100 cycles?
  4. whit3rd

    whit3rd Guest

    On Mar 25, 4:18 pm, wrote:
    Some bits might retain data through erasure. Basically, some charge
    storage in the FLASH cells could occur that doesn't get erased fully,
    leading to bad bits or low gain (slow response on READ).
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