Important Parameters to Consider When Selecting a Voltage Regulator

A voltage regulator is an integrated circuit (IC) that provides a constant output voltage regardless of load or input voltage changes. It can do this in a variety of ways depending on the topology of the circuit within, but we’ll focus on the linear regulator for the sake of keeping this project simple. A linear voltage regulator keeps the output voltage constant by automatically altering the resistance via a feedback loop, accounting for variations in both load and input.

A voltage regulator’s purpose is to keep a constant DC voltage at the output regardless of input voltage fluctuations and (or) load current variations. In other terms, a voltage regulator generates a DC output voltage that is regulated. Voltage regulators can also be found in the form of Integrated Circuits (ICs). In this blog, we discuss Important factors for voltage regulator selection.

Types of Voltage Regulators

There are two types of voltage regulators −

  • Fixed voltage regulator
  • Adjustable voltage regulator

Fixed voltage regulator

A fixed voltage regulator generates a constant DC output voltage that might be positive or negative.  In other words. certain fixed voltage regulators generate positive fixed DC voltage values while others generate negative fixed DC voltage values.

Positive fixed DC voltage values are produced by 78xx voltage regulator ICs, while negative fixed DC voltage values are produced by 79xx voltage regulator ICs.

Adjustable voltage regulator

A variable voltage regulator generates a DC output voltage that may be adjusted to any other value within a specific voltage range. As a result, a variable voltage regulator is also known as an adjustable voltage regulator.

An adjustable voltage regulator’s DC output voltage can be either positive or negative.

Important Factors for Voltage Regulator Selection

1. Input Voltage and Output Voltage

Knowing the input and output voltages you’ll be working with is the first step toward selecting a voltage regulator. A higher input voltage than the rated output voltage is required for linear voltage regulators. If the input voltage is less than the intended output voltage, the regulator will drop out and deliver unregulated output due to an insufficient voltage problem.

For example, if you are using a 5V voltage regulator with a 2V dropout voltage, the input voltage must be at least 7V for a regulated output. If the input voltage is less than 7V, the output voltage will be unregulated.

7805 Voltage Regulator

Voltage regulators come in a variety of shapes and sizes to accommodate a wide range of input and output voltages. For the Arduino Uno, for example, a 5V voltage regulator is required, while the ESP8266 requires a 3.3V voltage regulator. A variable voltage regulator, which can be used for a variety of output applications, is also an option.

2. Dropout Voltage

The voltage regulator’s dropout voltage is the difference between its input and output voltage. For instance, min. The 7805 has a dropout voltage of 2V since its input voltage is 7V and its output voltage is 5V. If the input voltage falls below a certain threshold, the output voltage (5V) plus the dropout voltage (2V) produces an unregulated output that can damage your device. Check the dropout voltage before choosing a voltage regulator.

Voltage regulators have varying dropout voltages; for example, there are a variety of 5V regulators with different dropout voltages. When used with a very low input dropout voltage, linear regulators can be exceedingly efficient. So, if you’re using a battery as a power source, then you can use LDO regulators for better efficiency.

3. Power Dissipation

The power dissipated by linear voltage regulators is more than the power dissipated by switching voltage regulators. Excessive power dissipation can result in battery drain, overheating, and product damage. Calculate the power dissipation first if you’re using a linear voltage regulator. Power dissipation for linear regulators can be computed as follows:

Power = (Input Voltage – Output Voltage) x Current

To eliminate the problem of power dissipation, switching voltage regulators can be used instead of linear voltage regulators.

4. Efficiency

Efficiency is defined as the output power to input power ratio, which is proportional to the output voltage to input voltage ratio. As a result, the dropout voltage and quiescent current directly limit the efficiency of voltage regulators, with the higher the dropout voltage, the lower the efficiency.

Drop-out voltage and quiescent current must be reduced for improved efficiency, as must the voltage differential between input and output.

5. Voltage Accuracy

The overall accuracy of a voltage regulator depends on line regulation, load regulation, reference voltage drift, error amplifier voltage drift, and temperature coefficient. The output voltage specification of most linear regulators guarantees that the controlled output will be within 5% of nominal. So, if the voltage regulator is used to power the digital ICs, a tolerance of 5% isn’t a major deal.

6. Load Regulation

The capacity of a circuit to maintain a set output voltage under varying load conditions is known as load regulation. The following is an example of load regulation:

Load Regulation = ∆Vout/ ∆Iout

7. Line Regulation

The capacity of a circuit to maintain a specific output voltage despite fluctuating input voltage is known as line regulation. The expression for line regulation is:

Load Regulation = ∆Vout / ∆Vin


Hope this blog helps you to understand how to select a proper voltage regulator for any application Hope you enjoyed the project and learned something useful. We, MATHA ELECTRONICS will come back with more informative blogs.

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