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Help with regulator IC

Discussion in 'General Electronics Discussion' started by dinhquochuy, Jul 3, 2013.

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  1. dinhquochuy


    Jul 3, 2013
    Hi all, I'm using a LD1085V50 power IC as a regulator, its datasheet has the information that this IC has "Internal power and thermal limitation".
    However when I accidentally short-circuited the output and the ground pin the IC instantly exploded, I cross-checked the datasheet and dont think I missed any of the peripherals needed for the IC to run properly.
    So what I want to ask you guys is that why it happened and how to prevent it?
    Thanks :D
  2. davenn

    davenn Moderator

    Sep 5, 2009
    Hi there
    Welcome to the forums :)

    well it may have "Internal power and thermal limitation" protection but it obviously doesn't appear to have short circuit protection ;)

    for long life of the chip DONT short circuit the output :)

  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    What happened is that you shorted the output.

    You can prevent this from happening again by being careful not to short the output.

    The internal power and thermal limits are not infallible. They often take some time to operate (as the temperature sensor is typically not embedded in the pass transistor) and they do not guarantee to protect the device -- and especially not in catastrophic situations like the one you imposed on it.

    You may be able to allow for stupid mistakes like this (and you would need to for a bench power supply for example) by having a current limit, or even a fuse. The former should act fast enough to prevent damage (or to allow the overload to be less and thus the thermal protection to work) but a fuse is likely to blow *after* the semiconductor has failed. A fuse will possibly stop the explosion and any subsequent fire if the device fails short circuit.
  4. dinhquochuy


    Jul 3, 2013
    Hey guys thanks for helping me, :D it turned out I messed things up in my PCB, i added diodes to prevent it from happening again. Thank you so much ^^
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