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Terminology question, no load capacitor and no load resistor — Parallax Forums

Terminology question, no load capacitor and no load resistor

Timothy D. SwieterTimothy D. Swieter Posts: 1,613
edited 2008-03-26 14:59 in General Discussion
I was reviewing a schematic I found on-line at Cypress Semiconductor for one of their capsense products.· While reading through the schematic I saw references to "no load" as the value on a couple capacitors and a couple resistors.· In the version notes of the schematic there was another note "zero ohm resistors replaced with no load resistors".·

I know what a zero ohm resistor is.· In the places in the Cypress schematic I think a zero ohm resistor would have done.· I don't understand what a "no load" capacitor or a "no load" resistor is.· Can any one educate me?

My best guess, and it is only a guess,·is that a "no load" cap or resistor is an actual device to be stuffed on the board but is really an open (instead of a short. 0 ohm).· Does that make sense?· Even though a device is populated it is still open?· Why populate the device then and instead just leave the footprint empty?· Perhaps to keep someone from accidentally stuffing it and causing a short?· That would make sense for the capacitors but I am not so sure about the resistor, but that probably depends on the application.

Thank you for any insights or defintions you can provide.

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Timothy D. Swieter

www.brilldea.com·- check out the uOLED-IOC, an I/O expansion for the uOLED-96-PROP
www.tdswieter.com
One little spark of imagination is all it takes for an idea to explode

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2008-03-26 07:28
    Timothy D. Swieter,

    I've heard the term used before when a board has multiple options, and the "no load" cap or resistor indicates that that component will NOT be populated on that board.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2008-03-26 07:58
    Hmmm - so "no load" is similar to Do Not Populate. That makes sense as I reviewed the schematic. The "no load" way of labeling things is perhaps even better than listing a part and a value and then on the BOM making it a Do Not Populate/stuff. I like having the majority of the data in one place so the person viewing the schematic is not confused and doesn't require so many other documents to decode and understand the design. I may have to implement this term in my designs, but make it clear that "no load" means do not populate.

    Thank you Beau for the response.

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    Timothy D. Swieter

    www.brilldea.com·- check out the uOLED-IOC, an I/O expansion for the uOLED-96-PROP
    www.tdswieter.com
    One little spark of imagination is all it takes for an idea to explode
  • steve_bsteve_b Posts: 1,563
    edited 2008-03-26 11:57
    hmmm....recently I was going through a schematic for a piece of gear at work.

    I was trying to trace a circuit that I later realized had a resistor that wasn't used....it was silkscreened on the board, but not placed.
    Taking a better look at the schematic I found that the "value" on that particular resistor simply has the letters SAT.

    My boss couldn't quite remember what it stood for....and I had not seen that before. Swapped At Test?? or Supplied At Test...??

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    <FONT>Steve



    What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
    Lee Travino after the second time being hit by lightning!
  • BeanBean Posts: 8,129
    edited 2008-03-26 14:59
    Steve,
    "Select At Test". We use them all the time at my work.

    Bean.

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