Supreem Circuits Diagram and Projects: Regulators

Simple Daul Regulator Handles Two Input Voltages

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The circuit in Fig 1 supplies both 3.3 and 5V to transitional circuits  that employ both the new 3.3V and older 5V devices. Additionally,  because the regulator accepts either 3.3 or 5V inputs, you could plug it  into either a new 3.3V system or an old 5V system.The circuit consists  of two sections: a dc/dc converter and a double-pole, double-throw  (dpdt) switch. The dpdt switch comprises a pair of dual n-channel  MOSFETs (Q2 and Q3) and their associated high-side drivers.<br />
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Upon power-up, the comparator in IC2 determines the state of the  circuit. The comparator’s output, IC2 pin 6, goes to the input of the  MOSFET driver, IC1. The driver internally generates a gatedrive voltage  8.8V above the device’s supply voltage. This high voltage drives the  appropriate MOSFETs in Q2 and Q3.<br />
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IC2 is also the heart of a flying-capacitor, buck/boost dc/dc converter.  Unlike other switching-<b>regulator</b> schemes, this topology needs no  transformers. Transistor Q1 controls this section’s output voltage, VS.  When VIN is at 5V, Q1 is off, forcing the section to operate as a  step-down converter. In this mode, the section produces 3.3V, which goes  to the output through Q3B. Also in this mode, 5V power goes directly  through Q2A, and Q2B and Q3A are both off.</div>
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When VIN is 3.3V, IC1 turns on Q1, shorting out the 140-kΩ resistor and  forcing the dc/dc-converter section into step-up mode. In this mode the  converter section generates 5V at VS, powering the 5V output via Q2B.  Also in this mode, 3.3V goes directly from the circuit’s input to the  output via Q3A. Q2A and Q3B are both off.No-load quiescent current  consumption is approximately 500 μA.<br />
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Lower-frequency converters would reduce power consumption at the expense  of a larger inductor. The efficiency of the dc/dc-converter section is  73% in either mode. But because this power accounts for only half of the  circuit’s output power, the circuit’s overall efficiency is  approximately 80% with VIN=3.3V and 86% with VIN=5V.  </div>
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Simple Daul Regulator Handles Two Input Voltages

The circuit in Fig 1 supplies both 3.3 and 5V to transitional circuits that employ both the new 3.3V and older 5V devices. Additionally, ...

Simple 7805 Voltage Regulator Circuit

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A <b>voltage regulator</b> is used to produce a constant linear output  voltage. It’s generally used with AC to DC power supply. And also it can  be used as well as a DC to DC voltage converter  . To regulating low voltage, most used device is one single IC. 7805,  7812, 7905 etc. 78xx series are design for positive and 79xx series are  for Negative voltage regulator. </div>
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<b>7805</b> is a three terminal +5v voltage regulator IC from 78XX chips family. See <i><b>7805 pinout</b></i> below. <b>LM78XX</b> series are from National Semiconductor. They are linear  positive voltage regulator IC; used to produce a fixed linear stable  output voltage.  National Semiconductor has also negative voltage  regulator chips family, they indicate with LM 79XX. 78xx is used more  than 79xx because negative voltage has a few usability purposes as we  see.<br />
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I was previously posted a 5v regulated <b>power supply</b> circuit using <b>7805 IC</b>, that circuit and this <i><b>7805 voltage regulator circuit</b></i> is almost the same.</div>
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Its output voltage is +5V DC that we need. You can supply any voltage in  input; the output voltage will be always regulated +5V. But my  recommendation is, don’t supply more than 18V or less than 8V in input.  There used two capacitors in this voltage regulator circuit, they aren’t  mandatory to use. But it will be best if you use them. They helped to  produce a smooth regulated voltage at output. Use electrolyte capacitor  instead of ceramic capacitor. </div>
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One limitation of <b>7805</b> I have found that is its output current <b>1A</b> maximum. Otherwise it is a good <b>voltage regulator</b> if you are happy with 1A. But if   you need <b>over 400mA</b> current in output then you should use a <b>Heat Sink</b> with IC LM7805. Otherwise it may fall damage for overheating.<a href="http://www.circuitstune.com/2012/09/7805-voltage-regulator-circuit-7805-pinout.html" rel="nofollow" target="_blank">Link</a></div>
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Simple 7805 Voltage Regulator Circuit

A voltage regulator is used to produce a constant linear output voltage. It’s generally used with AC to DC power supply. And also it can...

Simple Daul Regulator Handles Two Input Voltages

Simple 7805 Voltage Regulator Circuit

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