Leakage (electronics)
Encyclopedia
In electronics
, leakage may refer to a gradual loss of energy from a charged capacitor
. It is primarily caused by electronic devices attached to the capacitors, such as transistors or diodes, which conduct a small amount of current even when they are turned off. Even though this off current is an order of magnitude less than the current through the device when it is on, the current still slowly discharges the capacitor. Another contributor to leakage from a capacitor is from the undesired imperfection of some dielectric materials used in capacitors, also known as dielectric leakage. It is a result of the dielectric
material not being a perfect insulator
and having some non-zero conductivity, allowing a leakage current
to flow, slowly discharging the capacitor.
Another type of leakage occurs when current leaks out of the intended circuit, instead flowing through some alternate path. This sort of leakage is undesirable because the current flowing through the alternate path can cause damage, fires, RF noise, or electrocution. Leakage of this type can be measured by observing that the current flow at some point in the circuit doesn't match the flow at another. Leakage in a high-voltage
system can be fatal to a human in contact with the leak, as when a person accidentally grounds a high-voltage power line.
Leakage may also mean an unwanted transfer of energy from one circuit to another. For example, magnetic lines of flux will not be entirely confined within the core of a power transformer; another circuit may couple to the transformer and receive some leaked energy at the frequency of the electric mains, which will cause audible hum in an audio application.
Leakage current is also any current that flows when the ideal current is zero. Such is the case in electronic assemblies when they are in standby, disabled, or "sleep" mode. These devices can draw one or two microamperes while in their quiescent state compared to hundreds or thousands of milliamperes while in full operation. These leakage currents are becoming a significant factor to portable device manufacturers because of their undesirable effect on battery run time for the consumer.
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
, leakage may refer to a gradual loss of energy from a charged capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
. It is primarily caused by electronic devices attached to the capacitors, such as transistors or diodes, which conduct a small amount of current even when they are turned off. Even though this off current is an order of magnitude less than the current through the device when it is on, the current still slowly discharges the capacitor. Another contributor to leakage from a capacitor is from the undesired imperfection of some dielectric materials used in capacitors, also known as dielectric leakage. It is a result of the dielectric
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...
material not being a perfect insulator
Electrical insulation
thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...
and having some non-zero conductivity, allowing a leakage current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
to flow, slowly discharging the capacitor.
Another type of leakage occurs when current leaks out of the intended circuit, instead flowing through some alternate path. This sort of leakage is undesirable because the current flowing through the alternate path can cause damage, fires, RF noise, or electrocution. Leakage of this type can be measured by observing that the current flow at some point in the circuit doesn't match the flow at another. Leakage in a high-voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
system can be fatal to a human in contact with the leak, as when a person accidentally grounds a high-voltage power line.
Leakage may also mean an unwanted transfer of energy from one circuit to another. For example, magnetic lines of flux will not be entirely confined within the core of a power transformer; another circuit may couple to the transformer and receive some leaked energy at the frequency of the electric mains, which will cause audible hum in an audio application.
Leakage current is also any current that flows when the ideal current is zero. Such is the case in electronic assemblies when they are in standby, disabled, or "sleep" mode. These devices can draw one or two microamperes while in their quiescent state compared to hundreds or thousands of milliamperes while in full operation. These leakage currents are becoming a significant factor to portable device manufacturers because of their undesirable effect on battery run time for the consumer.