The LM series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 1. They are exceptionally easy to use and require only two external resistors to set the output voltage. Further, both line and load regulation are better than standard fixed regulators. Also, the LM is packaged in standard transistor packages which are easily mounted and handled. Included on the chip are current limit, thermal overload protection and safe area protection.
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Datasheet LM is a positive-voltage regulator with an adjustable voltage range from 1. It can supply greater than 1. In most of the applications, due to irregular loads, the output voltage produced has fluctuations in it which can lead to damaging loads.
Therefore, voltage regulators are used. The main function of the LM IC is to maintain the constant and stable voltage at the output.
It is used for linear regulation. These diagrams show the pinout of all types. However, the functionality of all pins is the same for each type. The details of pins are as under: Pin1 is an adjustable pin which is used to adjust the output voltage.
Pin2 is an output pin and gives a regulated voltage. An unregulated input voltage is applied at pin 3. This picture shows a functional block diagram of the adjustable voltage regulator. As you can see from the block diagram that it has built-in over temperature and over current protection circuits.
LM Voltage Regulator Features An adjustable positive voltage regulator The output voltage can be set through an adjustable input in a range of 1. This IC is intended for use in a regulation of variable voltages. It can be used for multiple purposes. It can be used as a fixed voltage regulator, AC voltage regulator, current limiter, Battery charger, local and on-card regulation.
It has one drawback that during regulation its voltage drop to about 2. The LM IC develops and maintains 1. Its output can be adjusted by connecting a network of two resistors externally between the output pin and adjust the input pin. The two decoupling capacitors are connected in a circuit. They are used to remove the undesired coupling and avoid the effect of noise. To use it is a variable regulator, we have connected a potentiometer at the adjustable pin.
By changing the value of a potentiometer, you can obtain the desired voltage at the output. We need only two external resistors. However, we can also use capacitors to avoid voltage variations at the input and output terminals. These capacitors help to remove ripples from output voltage. The output voltage of this circuit depends on resistor R1 and R2. How to add protection Circuits? The components can overheat due to more power dissipation.
For this reason, a heat sink is used to protect the IC from overheating. The external capacitors can discharge due to the low current of the regulator. Therefore, in some applications, protection diodes are added which prevent the capacitors from discharging. The Diode D1 protects the capacitor from discharging during an input short circuit while Diode D2 is used to protect CAdj by providing a low-impedance discharge path during an output short circuit. The output voltage is 7. You can also verify the results by putting resistors values in the formula given above.
We design simulation in proteus using the library. This simulation shows the variation in output voltage according to a change in R2 resistor value.
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