Last Updated on October 22, 2023 by Kevin Chen
Image of a transistor and LED light source TechZoro
We all know that diodes are integral components of the LED lighting systems. But there are other electronic components that make the LED lighting systems run perfectly as they are intended to. One of those components is the transistor. As long as an LD lighting device will be installed in a circuit, it will need additional electronic components to run perfectly. This is where transistors come in. These are discrete semiconductor devices that have a direct impact on the flow and behavior of the electric current.
When they increase the strength of the current, they are referred to as amplifiers. When they change the states of the circuits, they are referred to as switches. These two are just among many other functions of transistors in most electronic applications. In this guide, we are going to discuss the key roles of transistors in LED lighting.
An example of an LED lighting circuit with a transistor
To know the importance of transistors in LED lighting, let’s have a brief overview of an electric circuit that is designed to power the LED lighting fixture and at the same time contains a transistor and other vital electronic components such as resistors and capacitors.
The main function of a resistor and capacitor in such a circuit is to control the light illumination that is coming from the LED. An extended dimming period means that LED will be less bright than expected. The dimming time is usually determined by the resistance value.
Sometimes the current through the resistors is too weak due to high resistance. This means that you will need to boost it so as to achieve the highest output from the LED lighting. This is where the importance of using a transistor comes in. It is usually placed between the resistor and the capacitor in an LED circuit. The transistor will boost the current passing through the resistor resulting to a brighter illumination.
So, how does this work? The current that is coming from the resistor/capacitor is connected to the base terminal of the transistor. Technically, this current is weak. The output current through the emitter and collector will be strong enough to power up the LED lamp. The presence of the transistor will prevent the LED from dimming.
The block diagram below gives a perfect illustration of how this circuit works.
Block diagram source Dummies
The LED driver circuit below gives further illustration on the importance of transistors in LED lighting.
Image source LearningAboutElectronics
In the image above, both the LED and the transistor are connected to resistors. When the circuit is open, there is no flow of current through the base of the transistor. This automatically means that the transistor will remain in an OFF state. After all, BJT transistors can only turn on once there is a sufficient flow of electric current.
Once the right amount of base current is supplied, it will automatically turn on the transistor. Of course, the current through the collector and the emitter terminals will be amplified. This subsequently means that when the transistor is off, the LED lighting will also be off and once there is a flow of current through the transistor, the LED will turn on.
Other roles of transistors in LED lighting
In the above two examples, we have seen transistors acting as amplifiers in LED lighting systems. There are other functions of transistors in LED. These functions include the following:
In a typical transistor driver circuit, the electric current has first to go through the base terminal of the transistor before flowing to the LED. This setup allows the transistor to operate as a switch. If the current does not meet the required threshold, then the LED light will not turn on. Otherwise, it will allow the current to light up the switch.
The fast-switching speed of the field effect transistors makes them applicable to serve as switches. Switching in LED has a wide range of uses. Think of the indicator lights that are designed to rapidly turn on and off.
Protection and regulation
This is another core function of transistors in LED lighting systems. They regulate the amount of current that is flowing through the LED bulbs. It is possible to achieve this mainly due to the fact that transistors come in defined current and voltage capacities. This feature protects the LED from the risks of overcurrent which is likely to cause electrical damage.
Protection and regulation go beyond electric current. It also touches on some aspects of the device’s temperature. While LED lamps are usually considered efficient when it comes to heat dissipation, there have been numerous cases of heating problems on the LED lamps. Manufacturers have come up with various solutions and one of them is incorporating transistors in LED circuits.
When used for temperature regulation, transistors serve as heat compensators. They monitor the temperature conditions on the LED lamps the regulate the current. For instance, high temperature will trigger the transistor to lower the current hence reducing the dissipation of heat.
So, you see how transistors have a direct impact on the working and operation of LED lighting systems and applications. Remove a transistor from the LED circuits and you will not have tons of features that we usually witness in most LED applications.
Additionally, it is not just about using any transistor, but the right type and quality. If you are building an LED lighting system application, you should also pay some attention to the quality of the transistor that you intend to use. Premium-quality transistors for LEF lighting can only be sourced from reputable suppliers and distributors. This is where the importance of electronic components sourcing agents comes in. These are reputable entities that help buyers find quality electronic components from the best manufacturers and suppliers. The fact that they specialize in electronic components means that there is a high chance of finding you the exact products that you need. Even when you want to buy transistors in bulk.
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