LCD-LED Display

Simple LED Constant Current Source Schematic Circuit Diagram

Chip manufacturers are always coming up with ever more sophisticated constant current driver chips for LEDs. We have included this design for those of you who prefer a more cheap and cheerful solution.

Simple LED Constant Current Source Schematic Circuit Diagram

Regulating LED Current: Achieving Stable Illumination

Within this circuit, the LEDs’ current flow results in a voltage drop across resistor R1. As the current increases to yield a 0.6 V voltage drop across R1, T2 becomes conductive, diverting T1’s gate voltage to the ground. This action maintains a consistent current (I = 0.6 V/R1) flowing through the LEDs, ensuring their stable illumination.

Flexible Control Input: Tailoring LED Brightness

Facilitating versatile LED control, the input can activate the LEDs by applying voltages ranging from 5 V to approximately 12 V. Conversely, switching off the LEDs is achieved by applying a 0 V voltage. When modulated using a pulse width modulation signal, this input enables precise adjustment of LED brightness, providing a dynamic range of illumination possibilities.

Optimizing Supply Voltage: Maximizing LED Performance

For the series-connected LEDs, the supply voltage can be set at the highest practical level, ensuring optimal illumination. The key consideration lies in not surpassing T2’s maximum drain-source rating. The choice of T2 and the requirement for a heat sink hinges on the power dissipated within the device, a value that can be computed using a specific formula.

(Supply voltage minus the voltage drop across the LEDs) × ILED

The resistor is a passive electrical component that creates resistance in the flow of electric current. In almost all electrical networks and electronic circuits, they can be found. The resistance is measured in ohms (Ω). A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor.
The resistor absorbs the electrical energy in the process where it acts as a hindrance to the flow of electricity by reducing the voltage, and it is dissipated as heat. In today’s world of electronic circuits, heat dissipation is typically a fraction of a watt.

Types Of Resistors

  • Thermistors.
  • Varistor Resistors.
  • Photo Resistor or LDR (Light Dependent Resistors)
  • Surface Mount Resistors.

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