# Load Regulation And Line Regulation Pdf

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Line regulation is the ability of a power supply to maintain a constant output voltage despite changes to the input voltage, with the output current drawn from the power supply remaining constant.

Voltage regulation is classified into line regulation and load regulation. In line regulation output voltage is regulated when the input voltage changes.

Load regulation is the capability to maintain a constant voltage or current level on the output channel of a power supply despite changes in the supply's load such as a change in resistance value connected across the supply output. Load regulation of a constant-voltage source is defined by the equation: [3]. For a constant-current supply, the above equation uses currents instead of voltages, and the maximum and minimum load values are when the largest and smallest specified voltage across the load are produced. For switching power supplies, the primary source of regulation error is switching ripple, rather than control loop precision.

Voltage regulation is classified into line regulation and load regulation. In line regulation output voltage is regulated when the input voltage changes.

The purpose of load regulation is regulating output voltage when theload changes. To define Line regulation in percentage, it is the ratio of change in output voltage to change in input voltage.

If line regulation in percentage per volt is 0. As the load varies, load current changes thus output voltage changes. This change is independent to input signal. This should be reduced to a negligible value. Load regulation can be defined as the percentage change in output voltage for a given change in load current or load resistance.

If load regulation of a circuit is 0. Sometimes power supply manufactures mention output resistance instead of load regulation. Load regulation can be calculated from output resistance. Load regulation is also defined as the percentage of ratio of output resistance to full load resistance. Voltage regulators are again classified as linear regulator and switching regulators.

Both of them are also available as integrated circuits. As shown in the above figure their is a control element between input and output.

Error detector detects error by comparing reference voltage with sample voltage. Its comparison result is feed to control element which maintain a constant output voltage. Transistor is used as the control element and op-amp is used error detector. Out put voltage can be represented as,. From this equation, it is evident that output only depends on sample circuit resistors and zener diode.

That is, it would not change with input voltage, so regulation achieved. Short-Circuit or Overload Protection — If an excessive amount of load current is drawn, control element series-pass transistor will quickly destroyed.

To protect this resistor a current-limiting mechanism is required. Such a protection method is shown in the below figure.

This protection method is called constant-current limiting. Another method for overload protection is called fold-back current limiting. This method is used in high-current regulators whereby the output current under overload conditions fold back to a value well below the peak load current, It will prevent excessive power dissipation.

Linear series voltage regulator, have a transistor connected in series with the load to limit excess load current. Here a transistor is connected parallel to the load shunt.

As shown in the figure, control element is a transistor, in parallel with the load. A resistor, is in series with the load. Its working is similar to that of the series regulator, except that regulation is achieved by controlling the current through the shunt transistor.

When ever output voltage decreases due to change in the input voltage or load current, sample circuit sense it and feed to opamp and thus control element increases output voltage to ensure that it is regulated. Similarly sample circuit sense when output voltage increases beyond the required voltage and feed it to opamp. The shunt regulator is less efficient than the series regulator. But offers short-circuit protection.

Linear regulators discussed above is of two types, series and shunt. Both have control elements transistors. These transistors are conducting all the time. Amount of conduction varied according to the changes in the output voltage or current. But in Switching regulator control element in act as a switch.

So great efficiency can be achieved with the switching regulator than linear regulator, the transistor switches on and off and dissipates power only when it is on. All switching regulators require feedback to control the on-off time.

Thus it is useful when efficiency is important. Where as linear regulators act as a variable resistor, generate heat and power dissipation increases to a great extend. Switching regulators are designed for various power levels. It ranges from less than one watt to hundreds and thousands of watts. Required regulator is chose according to the application. Step-down configuration is also known as a buck converter.

The output voltage of Step-down is always less than the input voltage. The basic control element is a high-speed switch, which works rapidly. It senses the output from a control circuit and adjusts on time and off time to get the desired output. When the switch is closed, diode is off and the magnetic field of the inductor increases and energy storing takes place.

When the switch opens, the magnetic field decreases, results in constant current in the load. The capacitor in the figure makes the DC to a nearly constant level. Sometimes Thyristors are also used as switching devices, but its rare.

LC circuit in the above figure smooths pulse from the transistor. Inductor makes the current constant and capacitor makes the voltage constant.

Higher switching frequency much higher than the utility frequency is used to avoid requirement of large and expensive capacitors and inductors. But using higher frequency causes electrical noise. Switching power supplies radiate harmonic frequency noise to nearby circuits, so they are well shielded and EMI electromagnetic interference filters are used.

Step-up configuration is also known as a boost converter. The output voltage of Step-down is always greater than the input voltage. Voltage-Inverter Configuration is also known as buckboost converter. This third type switching regulator produces an output voltage opposite in polarity to the input.

We already discussed about the basic voltage regulator configurations. This section deal Integrated Circuit Voltage Regulators. There are several types of linear and switching regulators are available in the form of integrated circuit IC. Generally, the linear regulators are three-terminal devices.

It provide either positive or negative output voltages. This can be either fixed or adjustable. It is a three-terminal devices, which are input, output, and ground as indicated in the below figure. LM is an adjustable positive linear voltage regulator. It is a three-terminal devices, which are input, output, and an adjustable terminal to adjust output voltage. LM can vary its out put from 1.

The capacitors are for decoupling and do not affect the dc operation. LM is an adjustable negative linear voltage regulator. Like LM, It is a three-terminal devices and two external resistors for output voltage adjustment. LM can vary its out put from — 1. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Linear Series Voltage regulator. Basic op-amp series regulator. Series regulator with constant-current limiting.

Summing Amplifier using Op-Amp. Comparator Circuit using Op-Amp. Integrator and Differentiator using op-amp. Current Voltage Converters using Op-Amp. Voltage Regulation.

## Regulate Line Pdf

load as shown in the second plot. The output is also sensitive to input voltage changes. Figure 1: (a) Ideal power supply. (b) Real power supply. Line Regulation.

## Line regulation

Voltage Regulator. Released Datasheet. March 24, The most important thing we build is trust. The regulator is exceptionally easy to set-up, requiring only 2.

Line regulation is the ability of the power supply to maintain its specified output voltage over changes in the input line voltage. It is expressed as percent of change in the output voltage relative to the change in the input line voltage. Load regulation is the ability of the power supply to maintain its specified output voltage given changes in the load. This does not mean the tolerance applies when there are sudden changes in load, it means over the permissible load range the regulation can change by this amount. Both values apply to the output!

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