Archive for the ‘Voltage Regulators’ Category

Floating regulator

Floating regulator. Floating regulator is a type of voltage regulator that works without a real ground connection. This is a trick used for regulating voltages higher than the rated value. For example the typical output voltage range of LM723 voltage regulator IC is 2 to 37V DC. The upper limit can be pushed beyond 37V DC by using the floating technique. In floating configuration, the ground pin of the regulator will not be at the same voltage of the return path of the load current. This can be achieved by putting a Zener diode in series to the circuit ground. This makes…

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3A switching regulator

Description. When compared to linear voltage regulators the switching voltage regulators are much power efficient. In the case of linear voltage regulators the difference between the input and output voltage is just wasted and for switching regulators there is almost no such wastage and that’s why the switching regulators have great power efficiency ranging up to 85% . In simple words, the switching regulator operates by taking small bits of energy from the input voltage source and then transferring it to the output with the help of a solid state switch and a control circuitry. Since the switching element is…

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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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Fixed Positive Voltage Regulators

5Volts to 24volts Voltage Regulators using 78XX series IC 15 volts Power Supply The series 7800 regulators provide eight voltage options, ranging from 5 to 24 V. These ICs are designed as fixed voltage regulators and with adequate heat sinking can deliver output currents in excess of 1 A. Although these devices do not require any external component, such components can be employed for providing adjustable voltages and currents. These ICs also have internal thermal overload protection and internal short-circuit current limiting. Figure illustrates how one such IC, a 7815, is connected to provide voltage regulation with output of +…

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