For components that share a power supply, does their order on the positive line matter?

Discussion in 'The Projects Forum' started by jellytot, Jun 9, 2016.

  1. jellytot

    Thread Starter Member

    May 20, 2014
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    I have several components that draw power from the same source. Some of the components are "sensitive", but draw little current (e.g. MCU, sensors). Other components are "insensitive" (and/or noisy), but draw high or variable current (e.g. motors).
    I used to get random resets in my MCU. But I have since separated the sensitive grounds from the insensitive ones (2 main ground lines that join-up later down the line). Also, the more sensitive the equipment is, the earlier it is on its respective ground line. Resets are now very rare.

    My question is, does positioning of components matter on the positive line (in relation to effects on sensitive equipment like MCUs)? I'm about to add another component to my project. It's insensitive, and draws a lot of current. So I'll put its ground on the "noisy" line, farther down on the noisy ground line. Does it matter where I put the component on the positive line? Thanks!
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
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    619
    It could. More details = better responses.
     
    ErnieM likes this.
  3. ian field

    Distinguished Member

    Oct 27, 2012
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    You can get off the shelf power up sequencing chips. But if you have noisy loads in the same system as an MCU; you need to arrange rails filtering and decoupling so the noise is contained in the power rails.
     
  4. jellytot

    Thread Starter Member

    May 20, 2014
    72
    0
    The new component is a thermoelectric module that draws around 400-600ma. I can post other details if you wish, just let me know what you need. I'm still a beginner at electronics, so I was wondering if there were general rules on placement of components on the positive power line. Specifically, I don't want to increase the chances of my MCU resetting, or my sensors glitching.
     
  5. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
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    Make it appear to the various loads that they each have their own power source.

    The next best thing is divide up the supply rail paths - each with its own decoupling/filtering.
     
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