protection for microcontroller of electromagnetic interference and noise ?

Discussion in 'General Electronics Chat' started by Osama Mostafa, Oct 15, 2010.

  1. Osama Mostafa

    Thread Starter New Member

    Oct 15, 2010
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    how to make protection for microcontroller of electromagnetic interference and noise in power supply?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. Rbeckett

    Member

    Sep 3, 2010
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    Bertus,
    I'm confused, maybe the reply is for the wrong or a different thread. Makes no sense and I reas both. Thanks
    Bob
     
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  4. tom66

    Senior Member

    May 9, 2009
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    In some electronics where shielding is necessary for performance or legal reasons, you can use metal cans over the devices.

    [​IMG]

    This is one example. In this example there are two shields and one is being removed (this is from some kind of instruction manual.) The shields are soldered on the board, like through-hole components.

    The shields are usually custom designed, but you may be able to get a manufacturer to make some, or make them yourself.
     
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  5. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Your question is really too general. It depends a lot on your particular circuit configuration (I/Os, power source) and the anticipated environment. Do you have a specific application in mind?

    Ken
     
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  6. t06afre

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  7. Osama Mostafa

    Thread Starter New Member

    Oct 15, 2010
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    I will design stepper motor drive circuit by PIC microcontroller with current control which has a high frequency so I want to make sheilding for controller to avoid any elctromagnetic interference and any electrical noise from supply
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    This can be reduced quite a bit by good filtering on the power rails. Such as mid value electrolytics, small value ceramic caps, perhaps an inductor depending on frequency of noise. Separate the power for the uC from that of the stepper as much as possible, on the extreme end, use optocouplers to move the signal and feedback liines.

    Use a metal grounded case for the uC and components (faraday cage). Keep wire runs and PC Board traces short so they act less like antenna. Ensure you have a good ground plane on the PC Boards and they are well laden with bypass caps to keep the power supply filtered.

    Need more specific info on the interference, if it is a known frequency, a filter can be added to notch that particular frequency and most harmonics out.

    Same realm as a computer motherboard, or other digital circuits running at high clock frequencies. The design needs to ensure the traces do not turn into accidental radio transmitters. This is why 4 layer boards (sandwich with power and ground planes entirely across circuit) are used, as well as the smallest components for shortest trace lengths.
     
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