Synonyms for VDD/VCC?

Discussion in 'Power Electronics' started by seanspotatobusiness, Jun 7, 2017.

  1. seanspotatobusiness

    Thread Starter Member

    Sep 17, 2016
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    What are other things to refer to VDD or VCC? Can you call them the power pin/terminal or would that also include GND since that's also a necessary part of providing power. I'd like a word than be easily spoken and VDD and VCC are a little clumsy. "Positive" is a possibility but the signal wires also positive aren't they? Thanks!
     
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
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    When working with CMOS, everyone should understand that VDD is the positive supply, VSS is ground, and VEE is any negative supply. If you choose to use non-standard terminology, it will be clumsy.

    GND is often used as a synonym for VSS and VCC is often used instead of VDD.

    But, VCC and GND game from bipolar design.

    I've seen them mixed and matched, but people can usually figure out the intent of inappropriate terminology.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It has always somewhat irked me that there doesn't appear to be a logical acronym associated with the said terms?
    At least that I am aware of.
    Max.
     
  4. WBahn

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    Mar 31, 2012
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    VEE is also from bipolar design -- it's the supply voltage associated with the NPN emitter and is/was often used as the GND. I don't know that GND can really be said to come from the world of bipolar design - it is generic for "ground" and is often interchanged with COM (for "common"), which is usually the better term to use.
     
  5. WBahn

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    What you can get away with using depends on the context and the audience. Often it is good enough to use "power" or "supply" or even "rail" and the context of the discussion makes it clear whether you are talking about just one of the supply voltages or are talking about all of them collectively. In some contexts it goes the other way and isn't sufficient to use Vdd since you may have multiple supplies (or "grounds"). Our chips often had VddD, VddA, VssD, VssA for the digital and analog supply rails, though we eventually adopted the convention that Vdd and Vss would be used for the analog rails even if there were other supplies. When we had multiple voltages (usually for the digital circuits) we used Vdd5, Vdd3, and Vdd2 for the 5 V, 3.3 V, and 2.5 V rails (if it was something else we defined a different label for that project) and we used VddH for the high voltage analog supply, if there was one).

    As for the clumsiness, I think that feeling goes away after a while.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    From what I've read..
    Vc started from "Voltage collector" (and ve and vb) when transistors started coming around.. and you always had a resistor associated with that referred to as Rc (and Re and Rb) so combined became Vcc..
    Then mosfets came around so you got Vd (drain) and with its drain side resistor being Rd so Vdd

    That blah blah blah taken from here..
    https://en.wikipedia.org/wiki/IC_power-supply_pin
     
  7. dl324

    AAC Fanatic!

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    I used the conventions used in TTL datasheets from the 70's and the classes I took in college as the basis for my comment.
     
  8. MaxHeadRoom

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    Jul 18, 2013
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    I grew up with these:
    B+ and B- high-tension (HT) supply used in thermionic valve
    radio equipment.

    A+ and A- were the filament (heater) supply
    C+ and C- were grid bias
    Max.:rolleyes:
     
  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    How about just starting a new language for electronics? Where no one knows what the other is talking about? Oh, wait seems I remember something like that happening in a bible school story when I was young, something about a tower, I think.

    Seems like the new guy's always want to change protocol........ No offense meant, just an observation.
     
  10. EM Fields

    Active Member

    Jun 8, 2016
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    Me too, :)
     
  11. WBahn

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    Mar 31, 2012
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    It's probably impossible to really find out why the specific conventions evolved exactly as they are.

    One problem with Vc and Ve is that it is in conflict with the very widely used convention that a single letter subscript refers to the voltage on that node, So Vc is the voltage on Node C. But in many simple single-transistor BJT circuits (which are very common building blocks) the nodes c, b, and e (or d, s, and g for MOSFET circuits) are usually assigned to the nodes directly connected to those terminals. Double-letter subscripts, by that same widely used convention, are a short hand for a voltage difference such that Vce = Vc - Ve. But, by this convention, Vcc would always be identically zero, and is thus not a useful label -- which makes it available for use elsewhere without causing a conflict with this convention. So a double-letter subscript with a repeated letter generally refers to a DC signal (usually either a supply or a bias voltage) associated with the single-letter node.

    While I don't know the exact history of how that convention evolved or its timeline, it significantly predates the integrated circuit.
     
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