This document discusses the VI characteristics of light emitting diodes (LEDs). It explains that the VI characteristics describe the relationship between the current passing through an LED and the voltage across it. Understanding these characteristics is important for optimizing LED performance and troubleshooting circuits. The document also outlines different factors that can affect an LED's VI curve, such as temperature, current, and drive voltage.

1. Study the VI
Characteristics of
Light Emitting Diode
Light emitting diodes (LEDs) are semiconductor light sources that emit
light when a sufficient voltage is applied. Understanding their VI
characteristics is critical to optimizing their performance. Let's dive in!
by Vishnuvardhan VV

2. Introduction to Light Emitting Diodes
1 What are LEDs?
Light emitting diodes (LEDs) are semiconductor
devices that emit light when an electric current
passes through them. They're widely used in
lighting.
2
History of LEDs
LEDs were first invented in 1962 and were
originally used as indicator lights for electronic
devices. It took another 30 years for them to
become widely used as a source of illumination.
3 Advantages of LEDs
LEDs are much more energy-efficient than
traditional incandescent or fluorescent bulbs, they
last longer, and their light quality is superior.

3. What are VI Characteristics?
Definition
The VI characteristics of an LED
describe the relationship between
the current passing through it and
the voltage across it.
Types of VI Characteristics
There are two types of VI
characteristics: normal and
reverse. Normal VI curves are
graphed from the positive terminal
while reverse VI curves are
graphed from the negative
terminal.
Units of Measure
VI characteristics are usually
measured in volts and milliamps.

4. Why are VI Characteristics Important to Understand?
Optimizing Performance
Understanding VI characteristics is crucial
in selecting the right LED for a particular
application and designing the circuit for
optimal performance.
Troubleshooting Circuits
VI characteristics can also be used to
diagnose problems in circuits and
troubleshoot issues related to LED
operation.
Brightness Control
An understanding of VI characteristics can
be used to adjust LED brightness and
maintain consistent performance in different
applications.

5. How are VI Characteristics Graphed?
1
IV Curve Tracer
One common way to graph VI characteristics is to use an
IV curve tracer, which measures the voltage across and
the current through an LED and generates a curve.
2
Plotting Software
Another approach is to use specialized software to plot the
VI curve based on measurements taken from a circuit
using an LED.
3
Manual Graphing
VI characteristics can also be graphed manually by
measuring current and voltage at several points along a
circuit and plotting them on a graph.

6. Factors That Affect LED VI Characteristics
1 Temperature
Temperature affects the
forward voltage of an LED and
can change the shape of the VI
curve.
2 Current
Increasing the current through
an LED can cause it to heat up
and change its VI
characteristics.
3 Drive Voltage
The voltage used to drive an
LED can affect its brightness
and wavelength, which in turn
affects its VI characteristics.

7. Applications and Uses of Light Emitting Diodes
Lighting
• Indoor lighting
• Outdoor lighting
• Automotive lighting
Signage
• Backlit signs
• Electronic billboards
• LED displays
Consumer Electronics
• Computer monitors and TVs
• Remote control indicators
• Wearable technology

8. Conclusion and Summary
The Future of Lighting
LEDs are an important part of the future
of lighting technology, as they offer
superior energy efficiency, long life, and
excellent light quality.
The Importance of
Understanding VI
Characteristics
As an electrical engineer or technician,
understanding the VI characteristics of
LEDs is critical to optimizing their
performance in a wide range of
applications.
LEDs in Our Lives
LEDs are ubiquitous in our daily lives,
from the displays on our phones to the
traffic signals on our streets.