All About Circuits Forum  

Go Back   All About Circuits Forum > Electronics Forums > Homework Help

Notices

Homework Help Stuck on a textbook question or coursework? Cramming for a test and need help understanding something? Post your questions and attempts here and let others help.

Reply   Post New Thread
 
Thread Tools Display Modes
  #1  
Old 10-14-2009, 02:30 PM
onlyvinod56's Avatar
onlyvinod56 onlyvinod56 is offline
Senior Member
 
Join Date: Oct 2008
Location: hyderabad, india
Posts: 348
Blog Entries: 1
Default what is Vcc, Vss, Vdd & Vee?

hello...everyone

what is the meaning of Vcc....
i know that Vcc is the supply voltage for the electronic circuit.....
then what about the other things.....

can anybody contrast the "ground" from the Vss...
Reply With Quote
  #2  
Old 10-14-2009, 02:52 PM
t06afre's Avatar
t06afre t06afre is offline
Senior Member
 
Join Date: May 2009
Posts: 5,939
Default

In older days Vcc was often used for the 5 volt rail in TTL systems, Vdd for other positive supply rail, and Vee for negative supply rail. All measured in respect to ground. Then I make designs I prefer to labels like V+5, V+12, and V-12 etc
Reply With Quote
  #3  
Old 10-14-2009, 02:55 PM
onlyvinod56's Avatar
onlyvinod56 onlyvinod56 is offline
Senior Member
 
Join Date: Oct 2008
Location: hyderabad, india
Posts: 348
Blog Entries: 1
Default

Quote:
Originally Posted by t06afre View Post
In older days Vcc was often used for the 5 volt rail in TTL systems, Vdd for other positive supply rail, and Vee for negative supply rail. All measured in respect to ground. Then I make designs I prefer to labels like V+5, V+12, and V-12 etc
ok...thats good...but....
why they are named as CC.......DD..........SS............EE

is there anything linked about collector...drain.....source.....emitter?
Reply With Quote
  #4  
Old 10-14-2009, 02:56 PM
blueroomelectronics's Avatar
blueroomelectronics blueroomelectronics is offline
Senior Member
 
Join Date: Jul 2007
Location: Toronto, Canada
Posts: 1,704
Default

Cathode, Drain, Source, Emitter.
Reply With Quote
  #5  
Old 10-14-2009, 03:00 PM
onlyvinod56's Avatar
onlyvinod56 onlyvinod56 is offline
Senior Member
 
Join Date: Oct 2008
Location: hyderabad, india
Posts: 348
Blog Entries: 1
Default

Quote:
Originally Posted by blueroomelectronics View Post
Cathode, Drain, Source, Emitter.
cathode means something related to negative.........right
but Vcc will be considered as +ve...........

waht about this?
Reply With Quote
  #6  
Old 10-14-2009, 03:00 PM
bertus's Avatar
bertus bertus is online now
Administrator
 
Join Date: Apr 2008
Location: Amsterdam,Holland (GMT + 1)
Posts: 12,260
Default

Hello,

Here is a link:
http://encyclobeamia.solarbotics.net/articles/vxx.html

Greetings,
Bertus
__________________
You don't have to know everything, if you know where to find it.
When you do ask questions, you may look stupid.
When you do NOT ask questions, you will STAY stupid.

It would be nice to have the Timezone ( GMT +/- x ) in the location field in the profile.
(User CP -> Edit Your Details)
Reply With Quote
The Following User Says Thank You to bertus For This Useful Post:
screen1988 (03-21-2013)
  #7  
Old 10-14-2009, 03:58 PM
AlexR's Avatar
AlexR AlexR is offline
Senior Member
 
Join Date: Jan 2008
Location: Australia (UTC+10)
Posts: 735
Default

They are all supply voltages. Vcc = Collector supply voltage, Vee = Emitter supply, Vdd = Drain supply, Vss = source supply.

The voltages can be negative or positive depending on the the device and the circuit configuration. In circuits using NPN transistors Vcc is generally positive but if you were using PNP transistors then Vcc would be negative. In a circuit with a mixture of PNP and NPN devices Vcc take the polarity of the predominant technology used (generally it would be positive).
__________________
Alex

"A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools."-Douglas Adams
Reply With Quote
The Following 2 Users Say Thank You to AlexR For This Useful Post:
absf (03-20-2013), screen1988 (03-21-2013)
  #8  
Old 03-20-2013, 08:10 PM
newtonn newtonn is offline
New Member
 
Join Date: Sep 2010
Posts: 2
Default

this thread is great bcos have learn from it.
thks to the creator and the contributor.
Reply With Quote
  #9  
Old 03-20-2013, 09:44 PM
WBahn WBahn is offline
Senior Member
 
Join Date: Apr 2012
Location: Larkspur, Colorado
Posts: 8,077
Blog Entries: 9
Default

Quote:
Originally Posted by onlyvinod56 View Post
ok...thats good...but....
why they are named as CC.......DD..........SS............EE

is there anything linked about collector...drain.....source.....emitter?
They are derived from a more general naming convention.

If you have Va, Vb, or other voltages with a single subscript, then what is meant is the voltage of that node with respect to some reference node. That reference node is "ground" or "common" and is usually just indicated as "GND" or something similar. You are free to pick any node you want as your reference node, but usually one or two nodes are the most reasonable candidates.

If you have Vab or other voltages with two subscripts, then what is meant is the voltage of the first node with respect to the second node or

Vab = Va - Vb

This notation is actually quite useful because it allows you to figure out an unknown voltage step by step.

For instance, let's say that I want to know Vac but I only know Vab and Vbc. Well, I can use the subscipts to tell me that

Vac = Vab + Vbc

This is true because

Vac = Vab + Vbc

Vac = (Va - Vb) + (Vb - Vc) = Va + (-Vb + Vb) - Vc = Va - Vc

So in an expression, I can combine to voltages provided the first subscript on one of them is the same as the second subscript on the other by dropping the common subscript and keeping the other two in their same position.

So Vaf = Vab + Vbc + Vcd + Vdf

So, at this point, what would Vcc or Vee (or any other voltage with a repeated double subscript) be?

Vxx = Vx - Vx = 0V

Since any voltage with a repeated subscript will be 0V, the convention was adopted that a repeated subscript would indicate that the voltage was referring to a supply voltage, usually a DC supply. The letter would generally have some relevance to what the purpose of the supply was.

For BJT circuits, the three common supplies are Vcc, Vee, and Vbb for the collector, emitter, and base voltage supplies. The Vbb is sometimes an actual supply, but more often it is the thevenin equivalent voltage associated with the base bias network. One fine point is that, by general convention, Vcc and Vee are associated with the collector and emitter sides of an NPN transistor. This is commonly, but not universally, the case even if the only transistors in the circuit are PNP transistors. A quick glance at the schematic will tell you if this is the case or not.

For MOSFET circuits, the three common suppies are Vdd, Vss, and Vgg for the drain, sourse and gate supply voltages. The same remarks regarding polarity apply here.

The strict meaning of these has been lost among a growing number of people, and hence you will often see Vcc used as the positive supply in CMOS circuits and see Vdd in BJT circuits.

In many circuits, Vss/Vee is the same as the ground node, in which case it may or may not ever be noted as being Vss or Vee. In other circuits, there may be a more reasonable choice for the ground reference that is, generally, somewhere between the two values making Vss/Vee negative.
Reply With Quote
The Following 3 Users Say Thank You to WBahn For This Useful Post:
absf (06-15-2013), plant (06-14-2013), screen1988 (03-21-2013)
  #10  
Old 06-14-2013, 09:14 PM
plant plant is offline
New Member
 
Join Date: May 2013
Posts: 1
Default

Thanks to WBahn for this detailed reply.
btw, I'm replying because I don't see the "Thanks" button on any posts.
heh, but I have the "Thanks" button now that I've made a post.

Last edited by plant; 06-14-2013 at 09:16 PM. Reason: newly vivified options
Reply With Quote
Reply   Post New Thread

Tags
, , ,


Related Site Pages
Section Title
Textbook Thyristors : Solid-state Device Theory
Textbook Bipolar junction transistors : Solid-state Device Theory


Similar Threads
Thread Thread Starter Forum Replies Last Post
astable multivibrator circuit!! ( about frequency, and Vcc) lemoneyes Homework Help 3 05-22-2009 04:49 AM
Brake Pulse/Flasher Circuit doug3460 The Projects Forum 37 12-01-2008 12:31 PM
Airwires for VDD & VSS doug3460 The Projects Forum 0 11-20-2008 01:12 PM
CMOS read operation nearownkira Homework Help 4 05-15-2008 11:59 PM
PMOS problem with VSS and VDD FatherTime Homework Help 0 10-27-2007 10:09 PM

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 05:39 PM.


User-posted content, unless source quoted, is licensed under a Creative Commons Public Domain License.
Powered by vBulletin
Copyright ©2000 - 2014, vBulletin Solutions, Inc.