Current Divider: Definition, Applications & Formula

What Is A Current Divider?

A current divider is an electrical circuit configuration used to split or divide an input current into multiple branches or paths.  It consists of resistive elements connected in parallel.  

The purpose of a current divider is to distribute the total current flowing through the circuit among the different branches according to their respective resistances.

The current flowing through each branch of a current divider is inversely proportional to the resistance of that branch. 

 In other words, branches with higher resistance will have lower current flowing through them, and branches with lower resistance will have higher current flowing through them.

Working Principle OF Current Divider

The basic principle behind a current divider can be understood using Ohm's Law, which states that the current flowing through a resistor is directly proportional to the voltage across it and inversely proportional to its resistance. 

In a current divider, the total current (I) entering the circuit is divided between the branches based on their resistances.

The Current Divider Formula

The current through each branch (I1, I2, I3, etc.) can be calculated using the following formula:

I1 = (R2 || R3 || ...) / (R1 R2 R3 ... )   * I

Where:

- I1, I2, I3, etc. are the currents in each branch.

- R1, R2, R3, etc. are the resistances of each branch.

- (R2 || R3 || ...) denotes the combined resistance of the parallel branches.

- I is the total input current.

Current Divider Formula Example

Let's consider a practical example to demonstrate the current divider formula. Suppose we have a circuit with an input current of 2 amperes (I = 2A) and three parallel resistors connected in the circuit: R1 = 4 ohms, R2 = 6 ohms, and R3 = 8 ohms.

To calculate the current flowing through each branch (I1, I2, and I3), we can use the current divider formula:

I1 = (R2 || R3) / (R1 R2 R3) * I

I2 = (R1 || R3) / (R1 R2 R3) * I

I3 = (R1 || R2) / (R1 R2 R3) * I

Let's substitute the given values into the formula:

I1 = (6 || 8) / (4 6 8) * 2

I2 = (4 || 8) / (4 6 8) * 2

I3 = (4 || 6) / (4 6 8) * 2

To simplify the calculations, we need to calculate the equivalent resistances of the parallel combinations:

R2 || R3 = (R2 * R3) / (R2 R3)

R1 || R3 = (R1 * R3) / (R1 R3)

R1 || R2 = (R1 * R2) / (R1 R2)

Substituting the resistances:

R2 || R3 = (6 * 8) / (6 8) = 48 / 14 ≈ 3.43 ohms

R1 || R3 = (4 * 8) / (4 8) = 32 / 12 ≈ 2.67 ohms

R1 || R2 = (4 * 6) / (4 6) = 24 / 10 = 2.4 ohms

Now, we can substitute these values back into the current divider formula:

I1 = 3.43 / (4 6 8) * 2

I2 = 2.67 / (4 6 8) * 2

I3 = 2.4 / (4 6 8) * 2

Calculating the currents

I1 ≈ 0.2457 A (or 245.7 mA)

I2 ≈ 0.1917 A (or 191.7 mA)

I3 ≈ 0.1722 A (or 172.2 mA)

So, in this example, the current flowing through branch 1 (I1) is approximately 0.2457 amperes, the current through branch 2 (I2) is approximately 0.1917 amperes, and the current through branch 3 (I3) is approximately 0.1722 amperes.

Applications OF Current Dividers

Biasing in transistor circuits: Transistors require specific current levels to operate within their desired operating range. Current dividers can be used to provide the necessary bias currents to the base or gate terminals of transistors, ensuring proper functionality.

Current sharing in power supplies: In power supply circuits with multiple parallel output channels, current dividers are used to distribute the total output current evenly among the parallel channels. This helps balance the load and prevents overloading of any single channel.

Sensing and measurement: Current dividers are used in current sensing applications, where a fraction of the main current is diverted to a sensing resistor. This allows for accurate measurement of the current without affecting the main circuit operation.

Current limiting and protection: Current dividers can be employed in circuits to limit or regulate the current flowing through specific components. By setting the appropriate resistance values, the current can be controlled to prevent component damage or ensure safe operation.

Voltage-to-current conversion: In some cases, a voltage source needs to be converted into a proportional current. Current dividers can be used with appropriate resistive elements to achieve this conversion, providing a current output that is directly proportional to the input voltage.

Signal distribution: In communication systems or signal processing circuits, current dividers can be used to split an input signal into multiple branches, allowing the signal to be distributed to different components or subsystems.

Wheatstone bridge circuits: Wheatstone bridges are commonly used for measuring unknown resistances or for sensing changes in resistance. Current dividers are an integral part of these bridge circuits and help balance the bridge and provide accurate measurements.

These are just a few examples of how current dividers are utilized in various applications. The flexibility and controllability of current division make it a valuable tool in electrical and electronic circuit design.