Switching Regulator using LM1758 A

The National Semiconductor LM 1578 A is a switching regulator which can easily be set up for such dc-to-dc voltage .conversion circuits as the buck, boost, and inverting configurations. The LM 1578 A features a unique comparator input stage which not only has separate pins for both the inverting and non-inverting inputs, but also provides an internal 1.0 V reference to each input, thereby simplifying circuit design and PC board layout. The output can switch upto 750 m A and has output pins for its collector and emitter to promote design flexibility. An external current limit terminal may be referenced…

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Switching Regulators Using LM 2575 and LM 2577

Switching Regulators Using LM 2575 and LM 2577 Switching regu­lators are available is different circuit configurations in­cluding the flyback, feed-forward, push-pull, and non-iso­lated single-ended or single-polarity types. Also, the switching regulators can operate in any of three modes – step-down, step-up, or polarity inverting. LM 2575 series of regulators developed by National Semiconductor are monolithic IC’s that provide the active functions for step-down (back) switching regulator, capable of driving a1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V and an adjustable output version. Requiring a minimum number of…

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Switching Voltage Regulators

Switching Voltage Regulators All of the voltage regulators we have discussed so far are series regulators, also sometimes called the linear regulators because the pass transistor used in such a regulator operates in the active region. Series regulators are very popular and meet many of our needs. The main drawback of these regulators is the power dissipation in the pass transistor. As already mentioned above, the transistor used in these regulators is operated in its linear mode (active region). In essence, it is being used as a class A power amplifier. Conse­quently, it is not extremely efficient, and a great-deal…

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Dual Voltage Supplies

Dual Power Supply using LM 320 and LM 340 Bipolar or dual voltage supplies can be easily designed with the help of two 3-terminal regulators. This is shown in the figure above using the IC’s LM320 and LM 340. Opposite-phase ac is provided by the transformer’s secondary and a grounded center tap. The single full-wave bridge converts these into positive and negative dc voltages (with respect to the grounded center tap). The output of the rectifier circuit is filtered with the help of capacitors C1 and C2. You may also like : Voltage Regulators, IC Voltage Regulators and Regulated Power Supply While the LM…

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IC 723 Voltage Regulators

We have already explained in detail about the basics of regulated power supply, voltage regulators and IC voltage regulators. Let us take a look at one of the most popular IC voltage regulators, the 723 Voltage Regulator IC. The functional diagram of the voltage regulator is shown below. It consists of a voltage reference source (Pin 6), an error amplifier with its inverting input on pin 4 and non-inverting input on pin 5, a series pass transistor (pins 10 and 11), and a current limiting transistor on pins 2 and 3. The device can be set to work as both posistive…

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LM340 Series Voltage Regulators

Three terminal voltage regulators This series is typical of the three-terminal voltage regulators. The block diagram is shown in figure. The built-in reference voltage VREF drives the non-inverting input of an op-amp. The operational amplifier consists of several stages of volt­age gain. Because of the high gain of the op-amp, the error voltage between the two input terminals of the op-amp approaches zero. So the inverting input voltage is approximately equal to VREF. This means that current flowing through the potential divider I = VREF / R’2 Incidentally, the prime attached to R’2 indicates that this resistor is inside the…

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Adjustable Voltage Regulators

Adjustable Voltage Regulators Some­times variable voltage is required and under such a situation adjustable voltage regulator is used. A number of IC regulators, like LM 317, LM 338, and LM 350, are adjustable regulators. They have maximum load currents from 0.10 to 1.5 A. For example, the LM317 is a three terminal positive voltage regulator, which can be oper­ated with the output voltage regulated at any setting over the range of 1.2 V to 57 V. Figure illustrates how the regulated output voltage of an LM317 can be set. Resistors Rx and R2 set the output to any desired voltage…

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IC Voltage Regulators

A voltage regulator is one of the most widely used electronic circuitry in any device. A regulated voltage (without fluctuations & noise levels) is very important for the smooth functioning of many digital electronic devices. A common case is with micro controllers, where a smooth regulated input voltage must be supplied for the micro controller to function smoothly. You may also like this article on Regulated Power Supply Voltage regulators are of different types. In this article, our interest is only with IC based voltage regulator. An example of IC based voltage regulator available in market is the popular 7805…

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Zener Controlled Transistor Voltage Regulators

The efficiency of Zener regulated power supply becomes very low when the load current is high. Under such conditions a Zener controlled transistor is always used for maintaining output voltage constant. Basically there are two types of Zener controlled transistor voltage regulators. They are Series Voltage Regulators Shunt Voltage Regulators You may also go through the following articles: Regulated Power Supply, Voltage Regulators, Discrete Transistor Voltage Regulators, and IC Voltage Regulators Transistor Series Voltage Regulator or Emitter Follower Voltage Regulator     A simple series voltage regulator using an NPN transistor and a Zener diode is shown in the figure. This circuit is called…

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Discrete Transistor Voltage Regulators

Basically there are two types of transistor voltage regulators. They are (i) Series Voltage Regulators and (ii) Shunt Voltage Regulators. Each type of circuit can provide an output dc voltage that is regulated or maintained at a predetermined value even if the input voltage varies or the load connected to the output terminal changes. You may also go through the following articles: Regulated Power Supply,Voltage Regulators, Zener Controlled Transistor Voltage Regulators, and IC Voltage Regulators Series Voltage Regulator The basic connection of a series voltage regulator circuit is shown in the block diagram below. The series element controls the magnitude of the…

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