Voltage regulators play a crucial role in the power supply system. For example, in any working system where electric power is used like a mobile phone, wristwatch, PC, or laptop, the power supply is a central part of working the system because it allows consistent, reliable, and nonstop supply to the inside apparatuses of the system. In electric devices, the power supply offers stable as well as controlled power to work the circuits accurately. The power supply source are two categories –
- AC power supply that contracts from the mains outlets,
- DC power supply that employs from the battery’s storage.
So, this article discusses the voltage regulators’ basic information and their working.
What is a Voltage Regulator?
A voltage regulator is used to regulate/control a certain voltage level. When a steady, reliable voltage is required, then the voltage regulator is the ideal device. It makes a fixed output voltage level that remains constant for any fluctuations in an input voltage or load conditions. It works as a buffer for protecting mechanisms from damages. A voltage regulator is a mechanism with a simple feed-forward design, and it usually uses a negative feedback control loop setup.
There are primarily two sorts of voltage regulators available, and they are used in more comprehensive applications –
- Linear voltage regulators
- Switching voltage regulators
The linear voltage regulator is the simplest type of voltage regulator. It comes in two categories, which are compact and used in low power, low voltage systems. Let’s discuss various types of voltage regulators.
The main apparatuses used in the voltage regulator are listed below –
- Feedback Circuit,
- Stable Reference Voltage and
- Pass Element Control Circuit
The voltage regulation method is straightforward by using the mentioned three primary mechanisms. The first element of the voltage regulator, like a feedback circuit, is used to detect the DC voltage output changes. Depending on the reference voltage and feedback, a control signal can be generated and drives the Pass Component to pay off the changes.
Here, the pass component is a solid-state semiconductor similar to a BJT junction transistor, PN-Junction Diode, otherwise a MOSFET. Now, the DC output voltage can be kept approximately constant.
How does a Voltage Regulator Work?
A voltage regulator circuit maintains a permanent output voltage even when the input voltage varies. Otherwise, load conditions are changed. The voltage regulator obtains the voltage from a power supply, and it can be preserved in a range that is well-suited with the remaining electrical components. Most commonly, these regulators are used for converting DC-DC power, AC-AC, or else AC-DC.
Voltage Regulators’ Types and Working
Power distribution centers supplying AC power to residential and industrial consumers use more sophisticated and mechanically significant voltage regulators that maintain rated 110 V or 220 V based on different countries’ voltage regardless of feeding demands to the area.
Depend on the practical design, voltage regulators can be seen in the ICs, electromechanical appliances, or solid-state automatic regulators. The most familiar groupings of the active voltage regulators are linear and switching voltage regulators.
These regulators can be executed through IC or discrete component-related circuits. Voltage regulators are classified into two categories called linear voltage regulators & switching voltage regulators. These regulators are largely used to regulate a system the voltage level. Though, linear regulators exertion with low efficiency and also switching regulators, that work through high competence. The switching regulators with high-efficiency, most of the i/p power can be transmitted to the o/p without dissipation.
Fundamentally, there are two forms of Voltage regulators: Linear voltage regulator and Switching voltage regulator.
- There are two categories of Linear voltage regulators: Series and Shunt.
- There are three categories of Switching voltage regulators: Step up, Step down, and Inverter voltage regulators.
Linear Voltage Regulators
The Linear regulator performs as a voltage divider. The resistance of the voltage regulator differs with load resulting in stable output voltage. Linear voltage regulators are the unique type of regulators use to regulate the power supplies. In this kind of regulator, the active pass element’s variable conductivity like a BJT or the MOSFET is responsible to variating the output voltage.
Once a load is connected, the changes in any input otherwise the load will significant in a difference in current through the transistor to maintain the output is constant. To variation the current of the transistor, it worked in an active otherwise Ohmic region.
This kind of regulator dispels a lot of power throughout this procedure because the net voltage is dropped within the transistor to scatter like heat. Usually, these regulators are characterized into different categories.
- Positive and Negative Adjustable
- Static Output
- Tracking
- Floating
Advantages of a linear voltage regulator –
- It gives a low ripple voltage as output
- Fast response time to load
- Less noise and Low electromagnetic interference
The disadvantages of a linear voltage regulator
- Efficiency is very low
- Requires ample space – heatsink is needed
- Voltage upstairs the input cannot be bigger
Series Voltage Regulators
A series voltage regulator practices a variable component placed with the load in series. By varying the series elements’ resistance, the voltage that fell across it can be different. And the voltage across the load remains stable.
The quantity of current drawn is efficiently used by the load. This is the key advantage of a series voltage regulator. When the load does not need any current, it does not draw a full current. Consequently, a series regulator is significantly more effective compared to a shunt regulator.
Shunt Voltage Regulators
The shunt voltage regulator functions by applying a path from the supply voltage to the ground through a pot. The current through the shunt regulator has sidetracked from the load. It draws uselessly to the ground, making this form usually less effective than the series regulator. It is, however, more superficial, sometimes containing of just a voltage-reference diode, and is used in very low-powered circuits where the lost current is too small to be of concern. This form is widespread for voltage reference circuits. A shunt regulator can usually only absorb current.
Applications of Shunt Regulators
Shunt regulators are used in:
- Lower Output Voltage in Switching Electric Power Supplies
- Current Source
- Sink Circuits
- Error Amplifiers
- Adjustable Voltage
- Current Linear and Switching Power Supplies
- Analog-Digital Circuits for precision referencing and Precision current controllers
Switching Voltage Regulators
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 entirely conducting or switched off. After all, it dissipates almost no power. Switching regulators can generate output voltages that are higher than the input voltage or of opposite polarity, unlike linear regulators.
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
There are two kinds of topologies system
Isolated
It is created in radiation and intense environments. Yet again, isolated converters are catagories into two types which include the following.
- Flyback Converters
- Forward Converters
Non –Isolation
It is constructed on small changes in Vout/ Vin. Samples 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 an inductor.
Once more, non-isolated converters are classified into different types; however, the significant ones are
- Buck Converter
- Boost Converter
- Buck or Boost Converter
Advantages of Switching Topologies
The main compensations of a switching power supply are efficiency, size, and weight. It is also a more critical design, which is capable of handling higher power efficiency. A switching voltage regulator can provide output, which is greater than or less than or that inverts the input voltage.
Disadvantages of Switching Topologies
- Higher ripple voltage in the output
- Slower transient recovery time
- EMI create a huge noisy output
- Much expensive
Alternator Voltage Regulators
Alternators utilized the current that is mandatory to meet a car’s electrical requirements when the engine works. It also replenishes the energy which is used to start the car. An alternator can produce more current at lower speeds than the DC generators that were once used by most of the vehicles. The alternator has two parts
Stator – This is a fixed component. Stator does not move at all. It covers a set of electrical probes wound in coils over an iron core.
Rotor / Armature – It is the moving component that produces a rotating magnetic field by any one of the three ways: induction, permanent magnets, and using an exciter.
Electronic Voltage Regulator
A modest voltage regulator can be prepared from a resistor and diode series connection (or only using 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 necessary, this design may work fine.
Transistor Voltage Regulator
Electric voltage regulators have an unstable voltage reference source providing by the Zener diode. It is also familiar as the reverse breakdown voltage of the operating diode. It maintains a constant DC output voltage. The AC ripple voltage is choked, but the filter cannot be clogged. The voltage regulator also has an additional circuit for short circuit protection, current limiting circuit, over-voltage protection, and thermal shutdown.
Basic Parameters of Voltage Regulators
- The basic parameters that need to be considered while operating a voltage regulator mainly include the i/p voltage, o/p voltage, and o/p current. Generally, all these parameters are used primarily for defining the VR type topology is well-matched or not with the IC of a user.
- Another parameters of this regulator are switching frequency, quiescent current; feedback voltage thermal resistance may be relevant based on the demand
- Quiescent current is important once efficiency throughout standby modes or light-load is the primary concern.
- Once switching frequency is considered a parameter, exploiting the switching frequency can lead to a small system’s solutions. Also, the thermal resistance can be hazardous to dispose of heat from the device as well as remove the heat from the system.
- If the controller has a MOSFET, subsequently, all the conductive as well as dynamic losses will be dissolute within the package & must be well-thought-out once measuring the maximum temperature of the regulator.
- The most critical parameter is feedback voltage, as it adopts the less o/p voltage that the IC can embrace. This controls the less o/p voltage and the precision will affect the regulation of output voltage.
Limitations
As usual, there are some drawbacks of Voltage regulators. Let’s discuss some of these –
- One of the main boundaries of the voltage regulator is that they are ineffective because of the indulgence of huge current in some applications
- An IC voltage drop is alike to a resistor voltage drop. For instance, when the voltage regulator’s input is 5V & generates output like 3V, then the two terminals’ voltage drop is 2V.
- The regulator’s efficiency can be limited to 3V or 5V, which means these regulators are applicable with fewer Vin/ Vout differentials.
- In some sort of application, it is very significant to consider the expected power dissipation for a regulator. When the input voltages are high, power dissipation will be increased to damage different components because of overheat.
- Another limitation is that they can buck conversion compared with switching types because these regulators will provide buck and conversion.
- The switching regulators are efficient highly; however, they have some drawbacks like cost-effectiveness compared with linear regulators, more complex, large size & can produce more noise if their exterior components are not chosen cautiously.
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