Different Types of Voltage Regulators with Working Principle

 A voltage regulator is used to regulate voltage levels. When a steady, reliable voltage is needed, then the voltage regulator is the preferred device. It generates a fixed output voltage that remains constant for any changes in an input voltage or load conditions. It acts as a buffer for protecting components from damages. A voltage regulator is a device with a simple feed-forward design and it uses negative feedback control loops. There are mainly two types of voltage regulators: Linear voltage regulators and switching voltage regulators; these are used in wider applications. The linear voltage regulator is the easiest type of voltage regulator. It is available in two types, which are compact and used in low power, low voltage systems. Let us discuss different types of voltage regulators.

Voltage Regulator
Voltage Regulator

Types of Voltage Regulators and Their Working Principle

Basically, there are two types of Voltage regulators: Linear voltage regulator and Switching voltage regulator.

  • There are two types of Linear voltage regulators: Series and Shunt.
  • There are three types of Switching voltage regulators: Step up, Step down and Inverter voltage regulators.

Linear Regulator

Linear regulator acts as a voltage divider. In the Ohmic region, it uses FET. The resistance of the voltage regulator varies with load resulting in constant output voltage.

Advantages of a linear voltage regulator

  • Gives a low output ripple voltage
  • Fast response time to load or line changes
  • Low electromagnetic interference and less noise

Disadvantages of the linear voltage regulator

  • Efficiency is very low
  • Requires large space – heatsink is needed
  • Voltage above the input cannot be increased

Series Voltage Regulator

A series voltage regulator uses a variable element placed in series with the load. By changing the resistance of that series element, the voltage dropped across it can be changed. And, the voltage across the load remains constant.

Series Voltage Regulator
Series Voltage Regulator

The amount of current drawn is effectively used by the load; this is the main advantage of the series voltage regulator. Even when the load does not require any current, the series regulator does not draw full current. Therefore, a series regulator is considerably more efficient than shunt voltage regulator.

Series Voltage Regulator CircuitSeries Voltage Regulator Circuit
Series Voltage Regulator CircuitSeries Voltage Regulator Circuit

Shunt Voltage Regulator

A shunt voltage regulator works by providing a path from the supply voltage to ground through a variable resistance. The current through the shunt regulator has diverted away from the load and flows uselessly to the ground, making this form usually less efficient than the series regulator. It is, however, simpler, sometimes consisting of just a voltage-reference diode, and is used in very low-powered circuits wherein the wasted current is too small to be of concern. This form is very common for voltage reference circuits. A shunt regulator can usually only sink (absorb) current.

Shunt Voltage Regulator
Shunt Voltage Regulator

Applications of Shunt Regulators

Shunt regulators are used in:

  • Low Output Voltage Switching Power Supplies
  • Current Source and Sink Circuits
  • Error Amplifiers
  • Adjustable Voltage or Current Linear and Switching Power Supplies
  • Voltage Monitoring
  • Analog and Digital Circuits that require precision references
  • Precision current limiters

Switching Voltage Regulator

A switching regulator rapidly switches a series device on and off. The switch’s duty cycle sets the amount of charge transferred to the load. This is controlled by a feedback mechanism similar to that of a linear regulator. Switching regulators are efficient because the series element is either fully conducting or switched off because it dissipates almost no power. Switching regulators are able to generate output voltages that are higher than the input voltage or of opposite polarity, unlike linear regulators.

Switching Voltage Regulator
Switching Voltage Regulator

The switching voltage regulator switches on and off rapidly to alter the output. It requires a control oscillator and also charges storage components.

In a switching regulator with Pulse Rate Modulation varying frequency, constant duty cycle and noise spectrum imposed by PRM vary; it is more difficult to filter out that noise.

A switching regulator with Pulse Width Modulation, constant frequency, varying duty cycle, is efficient and easy to filter out noise.
In a switching regulator, continuous mode current through an inductor never drops to zero. It allows the highest output power. It gives better performance.

In a switching regulator, discontinuous mode current through the inductor drops to zero. It gives better performance when the output current is low.

Switching Topologies

It has two types of topologies: Dielectric isolation and Non- isolation.

Non –Isolation: It is based on small changes in Vout/ Vin. Examples are Step Up voltage regulator (Boost) – Raises input voltage; Step Down (Buck) – lowers input voltage; Step up/ Step Down (boost/ buck) Voltage regulator – Lowers or raises or inverts the input voltage depending on the controller; Charge pump – It provides multiples of input without using inductor.
Dielectric – Isolation: It is based on radiation and intense environments.

Advantages of Switching Topologies

The main advantages of a switching power supply are efficiency, size, and weight. It is also a more complex design, which is capable of handling higher power efficiency. Switching voltage regulator can provide output, which is greater than or less than or that inverts the input voltage.

Disadvantages of Switching Topologies

  • Higher output ripple voltage
  • Slower transient recovery time
  • EMI produces very noisy output
  • Very expensive

Step-Up Voltage Regulator

Step-up switching converters also called boost switching regulators, provide a higher voltage output by raising the input voltage. The output voltage is regulated, as long as the power is drawn is within the output power specification of the circuit. For driving strings of LEDs, Step up Switching voltage regulator is used.

 Step Up Voltage Regulator

                                       Step Up Voltage Regulator

Assume Lossless circuit Pin= Pout (input and output powers are same)

Then Vin Iin = Vout Iout ,

            Iout / Iin = (1-D)

From this, it is inferred that in this circuit

  • Powers remain the same
  • Voltage increases
  • Current decreases
  • Equivalent to DC transformer

Step Down (Buck) Voltage Regulator

It lowers the input voltage.

Step Down Voltage Regulator
Step Down Voltage Regulator

If input power is equal to output power, then

Pin = Pout; Vin Iin = Vout Iout,

Iout / Iin = Vin /Vout = 1/D

Step down converter is equivalent to DC transformer wherein the turns ratio is in the range of 0-1.

Step Up/Step Down (Boost/Buck)

It is also called Voltage inverter. By using this configuration, it is possible to raise, lower or invert the voltage as per the requirement.

  • The output voltage is of opposite polarity of the input.
  • This is achieved by VL forward- biasing reverse-biased diode during the off times, producing current and charging the capacitor for voltage production during the off times
  • By using this type of switching regulator, 90% efficiency can be achieved.
Step Up/Step Down Voltage Regulator
Step Up/Step Down Voltage Regulator

Alternator Voltage Regulator

Alternators produce the current that is required to meet a vehicle’s electrical demands when the engine runs. It also replenishes the energy which is used to start the vehicle. An alternator has the ability to produce more current at lower speeds than the DC generators that were once used by most of the vehicles. The alternator has two parts

Alternator Voltage Regulator
Alternator Voltage Regulator

Stator – This is a stationary component, which does not move. It contains a set of electrical conductors wound in coils over an iron core.
Rotor / Armature – This is the moving component that produces a rotating magnetic field by anyone of the following three ways: (i) induction (ii) permanent magnets (iii) using an exciter.

Electronic Voltage Regulator

A simple voltage regulator can be made from a resistor in series with a diode (or series of diodes). Due to the logarithmic shape of diode V-I curves, the voltage across the diode changes only slightly due to changes in current drawn or changes in the input. When precise voltage control and efficiency are not important, this design may work fine.

Electronic Voltage Regulator
Electronic Voltage Regulator

Transistor Voltage Regulator

Electronic voltage regulators have an astable voltage reference source that is provided by the Zener diode, which is also known as reverse breakdown voltage operating diode. It maintains a constant DC output voltage. The AC ripple voltage is blocked, but the filter cannot be blocked. Voltage regulator also has an extra circuit for short circuit protection, and current limiting circuit, over-voltage protection, and thermal shutdown.

Transistor Voltage Regulator
Transistor Voltage Regulator

This is all about different types of voltage regulators and their working principle. We believe that the information given in this article is helpful for you for a better understanding of this concept. Furthermore, for any queries regarding this article or any help in implementing electrical and electronics projects, you can approach us by commenting in the comment section below. Here is a question for you – Where will we use an alternator voltage regulator?

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9 Comments

  1. Katherine tk says:

    Thank you for sharing the information. this is the good information for every beginner.

    1. Tarun Agarwal says:

      Hi Katherine
      Thank you so much for your feedback

    2. Tarun Agarwal says:

      Hi Katherine tk
      We really appreciate you taking the time out to share your experience with us.

  2. Bhushan Deshmukh says:

    thanks its very much apt and valuable thanks

    1. Tarun Agarwal says:

      Hi Bhushan Deshmukh
      Thank you so much for your feedback

  3. Time saving n point to point explanation.

    1. Tarun Agarwal says:

      Hi Meenu
      Thank you so much for your feedback
      For more detailed information on voltage regulators, types and applications please refer to the link.

    1. Tarun Agarwal says:

      Thanks for your compliment
      For more detailed information on voltage regulators, types and applications please refer to the link.
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