6 LED IN PARALLEL

Designing a Parallel Circuit of Six LEDs with a Forward Bias Voltage of 2V and Forward Current of 20mA

Introduction: This write-up explores the design and characteristics of a parallel circuit consisting of six Light Emitting Diodes (LEDs). The LEDs will be connected in parallel with a forward bias voltage of 2V and a forward current of 20mA. The power supply for this circuit will be 9V. We will discuss the implications of this configuration and analyze the key parameters involved in the circuit design.

LED Basics: LEDs are semiconductor devices that emit light when a forward voltage is applied across their terminals. They are widely used in various applications such as lighting, displays, and indicators. LEDs have several advantages, including energy efficiency, long lifespan, and compact size.

Forward Voltage and Current: Each LED has a forward voltage (Vf) and forward current (If) specification. The forward voltage is the minimum voltage required to overcome the diode's internal resistance and allow current flow. The forward current is the optimal current at which the LED operates efficiently without getting damaged.

Parallel Circuit Configuration: Connecting LEDs in parallel means that all positive terminals of the LEDs are connected together and all negative terminals are connected together, creating multiple paths for current flow. This configuration allows each LED to have the same voltage applied across its terminals.

Design Calculation: Given that each LED has a forward voltage of 2V and a forward current of 20mA, and the total supply voltage is 9V, we need to ensure that the circuit parameters are within the safe operating range.

Voltage Calculation: In a parallel configuration, each LED will have the same voltage applied across its terminals. Therefore, the forward voltage requirement for each LED will remain 2V.

Current Calculation: The total forward current (It) flowing through the circuit will be the sum of the forward currents of all the LEDs in parallel. 

Therefore: It = 20mA x 6 = 120mA

Resistor Calculation: In a parallel LED configuration, a current-limiting resistor is not required for each LED since they share the same voltage. However, it is advisable to use a current-limiting resistor in series with the entire parallel combination to limit the total current flowing through the circuit. To calculate the value of the resistor (R), we can use Ohm's Law:

R = (Vs - Vt) / It = (9V - 2V) / 120mA = 58.33Ω

Results and Considerations: With a forward bias voltage of 2V and forward current of 20mA, and using a 58.33Ω current-limiting resistor in series with the parallel combination, we can create a parallel circuit of six LEDs. Each LED will have a forward voltage of 2V, and the total forward current flowing through the circuit will be 120mA.

It is important to note that while the calculations assume idealized LED characteristics, real-world variations in the forward voltage and current of the LEDs may exist. Additionally, thermal considerations should be taken into account to prevent overheating. Therefore, it is recommended to use appropriate heat sinks or consult the datasheets of the specific LEDs for detailed specifications and guidelines.

Conclusion: Designing a parallel circuit with six LEDs requires careful consideration of the forward voltage, forward current, and the supply voltage. By properly calculating the value of the current-limiting resistor and ensuring the voltage requirements are met, the circuit can be configured to ensure safe and efficient operation of the LEDs. It is essential to pay attention to real-world variations and thermal management to ensure the longevity and optimal performance of the LEDs.