All About Circuits Forum What is quiescent current?
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#1
05-17-2007, 07:29 AM
 sharath_412 Junior Member Join Date: May 2007 Posts: 32
What is quiescent current?

Hi,
What is quiescent current?
Is it the current consumed by the device when there is no load( regulator)?
Or is the definition based on the component used? for example regulators, Op amps etc.

#2
05-17-2007, 07:58 AM
 awright Member Join Date: Jul 2006 Location: San Francisco Bay Area Posts: 84

Your guess is correct. Quiescent current is the current drawn by a circuit when it is not amplifying a signal or driving a load (my definition, not an official definition).

I(q) of a DC-DC converter would be the current it draws when there is no load on the output so it is functioning (i.e., generating the desired output voltage), but is not supplying current to a load.

Same for an IC voltage regulator or an amplifier.

Think of it as the baseline current required to have the device ready to perform its task.

awright
#3
05-17-2007, 11:06 AM
 hgmjr Super Moderator Join Date: Jan 2005 Location: Tennessee, USA (GMT-6) Posts: 9,030 Blog Entries: 11

awright has stated the definition quite well.

At the risk of repetition, quiescent current is that amount of current consumed from a power source by a single component or group of components in a circuit when the circuit is in its powered but non-operating state.

hgmjr
#4
05-17-2007, 01:40 PM
 JoeJester Senior Member Join Date: Apr 2005 Location: Grand Prairie, TX, USA Posts: 2,346

quiescent
Etymology: Latin quiescent-, quiescens, present participle of quiescere to become quiet, rest, from quies
1 : marked by inactivity or repose : tranquilly at rest
2 : causing no trouble or symptoms

Definition 1 describes the quiescent condition of a circuit. Typically used in circuits when no drive signal is present.
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