This document discusses LEDs and how they can be connected in series or parallel circuits. It provides information on LED components, symbols, and how they work. When connected in series, all LEDs experience the same current but voltages are lost across each one. A parallel connection splits the voltage so each LED receives the same voltage. The key advantages are that a series circuit remains intact if one LED fails, while a parallel circuit can have individual LEDs burn out without affecting the others. Applications of LEDs include lighting, electronics displays, and traffic signals.

1. LED – Series and Parallel
Connection
Dr.R.Hepzi Pramila Devamani
Assistant Professor of Physics
V.V.Vanniaperumal College for Women,
Virudhunagar

2. Introduction
• A light-emitting diode (LED) is a semiconductor light source that emits
light when current flows through it. ... White light is obtained by using
multiple semiconductors or a layer of light-emitting phosphor on the
semiconductor device.
• The LED is a special type of diode and they have similar electrical
characteristics to a PN junction diode. Hence the LED allows the flow of
current in the forward direction and blocks the current in the reverse
direction.
• The lighting emitting diode is a pn junction diode. It is a specially doped
diode and made up of a special type of semiconductors. When the light
emits in the forward biased, then it is called a light-emitting diode.

3. LED Symbol
• The LED symbol is similar to a
diode symbol except for two
small arrows that specify the
emission of light, thus it is called
LED (light-emitting diode).
• The LED includes two terminals
namely anode (+) and the
cathode (-). The LED symbol is
shown below.

4. Working of LED
• When the diode is forward biased, then the electrons & holes are
moving fast across the junction and they are combined constantly,
removing one another out.
• Soon after the electrons are moving from the n-type to the p-type
silicon, it combines with the holes, then it disappears.
• Hence it makes the complete atom and more stable and it gives the
little burst of energy in the form of a tiny packet or photon of light.

5. Advantages
• The cost of LED’s is less and they are tiny.
• By using the LED’s electricity is controlled.
• The intensity of the LED differs with the help of the microcontroller.
• Long Lifetime
• Energy efficient
• No warm-up period
• Rugged
• Doesn’t affect by cold temperatures
• Directional
• Color Rendering is Excellent
• Environmentally friendly
• Controllable

6. Disadvantages
• Price
• Temperature sensitivity
• Temperature dependence
• Light quality
• Electrical polarity
• Voltage sensitivity
• Efficiency droop
• Impact on insects

7. Applications
• LED is used as a bulb in the homes and industries
• The light-emitting diodes are used in motorcycles and cars
• These are used in mobile phones to display the message
• At the traffic light signals LED’s are used

8. Series and Parallel Connection
• There are three kinds of connections of an electrical circuit or
electronic circuit: serial connection, parallel connection, and series-
parallel (combination circuit).
• The two that occur most are the easiest: serial connection, parallel
connection.
• If we take Led lights, for example, they can be connected in a parallel
or serial connection.
• A serial connection is when components are connected along a single
path. A parallel connection is when components are connected along
multiple paths.

9. Series Connection
• LEDs that are connected in a series,
are connected along a single
conductive way, so the same
current runs through all of the
components but voltage are lost
over each of the LEDs.
• In a series circuit, the sum of the
voltages used by each unique
resistance is equivalent to the
source voltage.
• A serial connection is required with
LED lighting if you use a current-
controlled power supply.

10. Series Connection
• Consider a circuit consisting of
four LED light bulbs and a 12-
volt battery.
• If a wire runs the battery to one
bulb, to the next bulb, to the next
bulb, to the next bulb, and then
back to the battery in one
unbroken loop, the bulbs are said
to be in series connection as
shown in Figure.

11. Series Connection
• In a serial connection, the current
can’t continue and the LEDs are
turned off.
• So whenever at least one LED is
broken, the circuit is interrupted.
The broken LED can no longer
conduct the current so that all
LEDs on the circuit break down.

12. Parallel Connection
• By using a parallel connection the
voltage is split up and each LED is
applied the same amount of
voltage.
• If you use a circuit with just LEDs
connected in series it’s a serial
connection and if you connect them
in a parallel way that’s known as a
parallel circuit.
• A parallel connection is required
with LED lighting if you use a
voltage power feed.

13. Parallel Connection
• If each LED bulb is wired to the
battery in a separate loop, the
bulbs are said to be in parallel
connection.

14. Parallel Connection
• With a parallel connection, the
rest of the LEDs continue to
operate even if one of the LEDs
burn out, – The circuit stays
intact.

15. Video
• LED – Series and Parallel Connection

16. THANK YOU