Talk:IC power supply pin

From Wikipedia, the free encyclopedia

	This article is part of WikiProject Electronics, an attempt to provide a standard approach to writing articles about electronics on Wikipedia. If you would like to participate, you can choose to edit the article attached to this page, or visit the project page, where you can join the project and see a list of open tasks.
???	This article has not yet received a rating on the quality scale.
???	This article has not yet received a rating on the importance scale.

I think this article should be moved to something like IC power supply pins and extended to cover them equally. what do other people think? Plugwash 21:13, 16 August 2005 (UTC)

Sure. - Omegatron 21:16, August 16, 2005 (UTC)

Contents 1 History (clipped) 2 Alternative explanation for double letter notation 3 NC means "not connected" 4 Diagram 5 Generic IC Image Incorrect?

[edit] History (clipped)

V_CC (note: lower case is sometimes used instead of subscript, e.g. "Vcc") is an abbreviation for "common-collector voltage". V_EE refers to similar pins on devices with common-emitter connections. TTL logic usually uses a bipolar junction transistor process, so uses the V_CC–V_EE labeling. Since NPN transistors are the more common variety V_CC became positive and V_EE negative.

Meanwhile NMOS used V_DD (drain), and V_SS (source) labels for positive and negative respectively. This notation continued with CMOS even though it has drains connected to both power supply rails. As logic families have evolved the power supply pin labeling may not have much to do with the connections to the actual transistors.

[edit] Alternative explanation for double letter notation

I have always belived that the double letter notation is to make it simular to all the other notations in transistors. For instance, Vds, meaning the voltagedrop between drain and source. Vdd, Vss, Vcc and Vee are voltages that isn't actually relative to anything which is different from Vd, Vs, Vc and Ve that all are relative to ground. So you can't just drop a letter, and it isn't relative to the other terminals. Therefor, it is my belife, that it simply means drain-drain, source-sourc etc. which means that it is relative to whatever you want it to be relative to.

This might not be the best explaination. It might be due to me being wrong, or that I am correct, but not very good to express myself in english. However this a topic that is hard to find the actually facts about. I just took part in a lecture where the professor didn't know the answer, and I am a master of science in hardware design myself.

129.241.206.21 16:21, 8 February 2007 (UTC)Mr.Kalle

[edit] NC means "not connected"

Someone coming here is probably looking for help understanding an IC connection diagram. In that context, it would be good to include something about what "NC" means. —The preceding unsigned comment was added by 190.56.56.246 (talk) 13:32, 17 April 2007 (UTC).

[edit] Diagram

Added a diagram, removed {{reqdiagram}} tag. Tswsl1989 13:50, 15 June 2007 (UTC) (Update: forgot to tl template Tswsl1989 07:48, 20 June 2007 (UTC))

[edit] Generic IC Image Incorrect?

The image of the generic IC seems to have two positive supply inputs (Vcc and Vdd). I assume one of these should be a negative supply input (probably change Vdd to Vss or Vee). —Preceding unsigned comment added by 58.174.32.2 (talk) 00:19, 22 November 2007 (UTC)

I noticed this too - it also seems wrong to me. Should it be deleted? Hithisishal (talk) 06:17, 31 January 2008 (UTC)

I just noticed this. It's rather impractical for an IC to have two positive rails, so while it is theoretically a real IC, it will also confuse people. —Preceding unsigned comment added by 128.12.119.156 (talk) 14:34, 16 May 2008 (UTC)