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Thread: uln is getin heated !!!!!!!!!!!!!!!!!!

  1. #1

    Default uln is getin heated !!!!!!!!!!!!!!!!!!

    hiiiii everybody..............................

    i'm usin uln2803 driver for pathfinder @NITRKL
    but problem is that it's gettin hested after abt 15 to 20 secs then stops workin................


    any suggestion plz..........
    how to reduce heat??????????
    i need around 30 secs for perfect work..........................

  2. #2
    Administrator T-1000 vikas's Avatar
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    Default

    use a heat sink ... with some paste .

  3. #3

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    Heating occurs due to

    exceed the ampere rating of the IC
    improper connections
    connecting output as input

  4. #4

    Default

    thnx................................

    isn't heat sink much bigger than a uln 2803 driver?????????????????


    how can it be used efficiently as power supply is also another problem!!!!!!!!!!!!!!!!!!!!1111

  5. #5
    Senior Member T-1000
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    heating is happening due to two reasons...

    ur motors draws more current than wat uln can support{>500ma}

    and the second reason may be due to eranous connections.

    as far as heat sink goes, it has to be big.
    then only it can dissipate heat to surrounding. it ll work a lot better if u can have a fan blowing air around the ic.
    but i don think tat its a very gud idea to use heat sinks for ic's.... such as uln2803{pdip}.check ur connections and if ur motor draws too much current, switch over to transistor or mos based discrete component circuits.

    but surely use a heat sink for ur power supply if u r using 7805 regulator.
    if u thought u r the only mad person on the planet.......u got serious competition here

  6. #6
    Senior Member Cyborg devpriya's Avatar
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    I think that you are drawing more current from ULN, so why dont you put two channels in parallel...... This is a well known technique used to drive devices with higher current ratings.

    Try putting the channels in parallel and tell me your observation.

  7. #7

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    ya............ it's true motors r drivin larger currents


    it's really a good idea to use parallel channels.it can surely reduce the loads ....................

    but i'm drivin stepper motor......so if i'm understandin u perfectly.........then i think it would only applicable 4 dc motors where only 1 input is given............

    so plz explain litle more on this............

  8. #8
    Senior Member T-1000
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    its applicable in both cases...
    dc motor ll be having 2 connections whereas steppers ll have 4...
    uln supports about 500ma, so it makes sense to connect them in parallel if the current reqd. by motor is not too high...
    after all u cant go on connecting a huge no. of uln's in parallel.
    if u thought u r the only mad person on the planet.......u got serious competition here

  9. #9

    Default

    Hi,

    You could try stacking them up like this

    http://www.solarbotics.net/library/c...river_245.html

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