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+12V vehicle protection standards

Discussion in 'Electronic Design' started by Allan Herriman, Nov 10, 2007.

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  1. Hi,

    I'm designing something to plug into a (nominal) +12V cigarette
    lighter socket in a vehicle.

    Can someone please point me in the direction of STANDARDS which
    describe the electrical environment? I'm particularly interested in
    surges, overvoltages, etc.

    BTW, I'm not really interested in knowing your circuit solution to
    automotive protection, but post anyway; there'll be others who might
    get something out of it.

  2. Wimpie

    Wimpie Guest

    Hi Allen,

    type: iso 7637 level into google, altavista, webcrawler, etc and
    you find documents that refers to ISO 7637 test levels for EMC. The
    ISO standard is not free available.

    Prepare yourself for heavy spikes. There is a difference in levels
    for equipment directly connected to the car battery and other means of

    When you download EN 301 489-3 (EMC for SRD equipment, free from the
    ETSI website) they also mention levels for 12 and 24 V board nets and
    refer to ISO 7637.

    Regarding the DC level. A car generator should not charge the
    battery above 15V, however, some do.

    Best regards,

  3. Jim Stewart

    Jim Stewart Guest

    National Semi also wrote an excellent
    ap note on the subject. It was a long
    time ago. So many years I'm embarrased
    to say :)
  4. Wimpie

    Wimpie Guest

    Hi Allen,

    I forgot to mention, they have a nice document
    (¡free!) on all vehicular EMC (inclusive conducted immunity via supply

    Best regards,

  5. Ralph in NH

    Ralph in NH Guest

    There's some good info here -

    Also, google "alternator load dump" and/or "automotive transients" you
    should get at least a few links to $tandards.

    Best regards,
    Ralph in NH


    and this is the cure for insomnia

  7. neon


    Oct 21, 2006
    fool you cannot do anything from a cigaret outlet from a car protect what the battery i supose. you might get 3 amps out the generator and battery can supply 2 horsepower and more. read books first.
  8. legg

    legg Guest

    Old GE/Harris/Intersi/Littelfuse app note 9312

    Military standards are pretty comprehensive, but are for 28V systems.

    Ford describes surge waveforms and immunity levels expected in section
    14 of EMC Spec ES-XW7T-1A278-AC.


  9. Thanks to all who replied.

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