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Resistor power rating

Discussion in 'Electronic Basics' started by galapogos, Jan 31, 2007.

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  1. galapogos

    galapogos Guest


    I'm wondering if there's some sort of a chart or reference to find out
    what kinda package is needed for what kind of power rating for SMT
    ceramic resistors. I have a design where I need a 0ohm resistor that
    passes up to 2A @5VDC. Would a 1206 size be sufficient?

  2. You mention power rating and current. If a resistor is
    really zero ohms, it doesn't dissipate power, regardless of
    the current. Of course, no room temperature superconductors
    are yet available, so any real resistor will have some
    resistance, even if it is sold as a zero ohm device. You
    really have to go to the data sheet and see what its current
    rating is, but I am pretty confident that a 1206 zero ohm
    jumper would be fine carrying 2 amperes.
  3. tlbs101

    tlbs101 Guest

    Most zero-Ohm resistors I have seen are sub-100 milliOhm, nominally
    between 10 and 50 milliOhm. Even in absolute worst-case if one of
    them happened to come up 100 mOhm, I^2*R loss would only be 0.4 W and
    the 1206 package can take that for a short while.

    A much more likely worst-case scenario would be 50 mOhm, which would
    disspilate less than 0.2W, for which the 1206 is generally rated.

    Check the manufacturer's data sheet for their zero-Ohm parts. That
    will usually tell you what the nominal and max. "zero Ohm" resistance
    really is.

    Tom P.
  4. galapogos

    galapogos Guest

  5. What weight and width of copper traces are you using to
    carry this 2 ampere current?
  6. galapogos

    galapogos Guest

    Actually it's not really 2A. 2A is the upper limit. I'm probably
    expecting something to the order of 1A or less typical.
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