Overview ensembleLe transistor (or other device) is used as half of a voltage divider to control the output voltage and a feedback circuit compares the output voltage to a reference voltage to adjust the input of the transistor, which maintains the output voltage reasonably constant. This procedure is inefficient since the transistor behaves like a resistor, it will lose power by converting it into heat. In fact, the loss of power due to heating in the transistor is the current time the voltage dropped across the transistor. The same function can be performed more efficiently by switching power supplies (SMPS), but it is more complex and the switching currents in it tends to produce electromagnetic interference. An SMPS can easily provide more than 30A of current at voltages as low as 3V, while for the same voltage and current, a linear regulator would be very heavy and linear volumineux.régulateurs come in two basic forms: regulators of the series and shunt.régulateurs regulators of the series are the most common form. The linear regulator works by providing a path from the supply voltage of the load through a variable resistor (the main transistor is in the top “half” of the voltage divider). The power dissipated by the regulator is equal to the output of the power by the current of the voltage drop across the shunt régulation.Le device works by providing a path from the supply voltage to the ground by a variable resistor (the main transistor is in half “down” the voltage divider). The current through the shunt is diverted from the load flow and burdening the earth, making it even less effective as the standard controller. It is, however, more simple, sometimes consisting of only a diode voltage reference, and is used in very low power circuits, where the current is wasted too small to be of concern. This form is very common for voltage circuits référence.Tous linear regulators require an input voltage at least a minimum amount above the desired output voltage. This minimum is called voltage drop. For example, a common regulator such as the 7805 has an output voltage of 5V, but can not maintain that if the input voltage remains above about 7V. Its output voltage drop is 7V – 5V = 2V. When the voltage is less than 2V above the desired output voltage, as is the case in low voltage microprocessor, known as low-dropout regulators (LDOs) must be utilisé.Quand we want a higher voltage than the input voltage available, no linear regulator works (not even an LDO). In this situation, a switching regulator must be used. Simplerégulateur Zener voltage regulator zenerL’image simple zener regulator shows a simple tension. It is a shunt regulator and operates through the action of the zener diode to maintain a constant voltage across itself when the current through, just take it in the zener breakdown region. Resistor R1 provides current Zener IZ and IR2 load current (R2 is the load). R1 can be calculated as – where VZ is the Zener voltage, and IR2 is the load current nécessaire.Ce regulator is used for simple applications where low power currents involved are very small and the load is permanently connected through the Zener diode (as a reference voltage source or voltage circuits). When R1 was calculated, R2 will delete the full load current (over current components) flowing through the diode and may exceed the maximum current rating of the diode and cause damage. The resolution of this circuit is also not very good because the Zener current (and therefore the zener voltage) varies according to VS and inversely with current load. Simplerégulateur series regulator voltage single stage of a transmitter sérieAjout simple Zener regulator follower forms a simple series voltage regulator and substantially improves the resolution of the circuit. Here, IR2 load current is supplied by the transistor whose base is now connected to the zener diode. Thus, the transistor base current (IB) as the load current for the zener diode and is much lower than the current in R2. This regulator is classified as “series” because the regulatory element, ie. , The transistor is in series with the load. R1 defines the Zener current (IZ) and is determined – where VZ is the Zener voltage, base current IB and K = 1, the transistor. 2-2 (ensuring that R1 is small enough for adequate IB). Where, IR2 is the charging current required and it is also common emitter transistor (assumed to be equal to the current collector) and HFE (min ) is the minimum acceptable DC current gain for the circuit transistor.Ce regulations much better than the simple Zener regulator, since the base current of the transistor is a very light load on the zener, thereby minimizing variations due to zener voltage variation of the load. Note that the output voltage will always be about 0. 65V zener unless the reason for the drop VBE of the transistor. Although this circuit has a good regulation, it is still sensitive to the load and supply change. He did not exclude the possibility of being adjustable. These two problems can be solved by incorporating a negative feedback loop in it. This regulator is often used as a “pre-regulator in several advanced controller series circuits tension.Voir also: Using multiplier capacity linéairerégulateurs linear regulator can be built with discrete components, but are usually found in the forms of integrated circuits. The linear regulators are the most common three-terminal integrated circuit in the TO220 package. (The TO-220 is the same kind that many medium power transistors commonly come: three feet straight, protruding from a black molded plastic case with a metal plate with a hole for the locking of a heat sink). Common voltage regulators in solid series are LM78xx (for positive voltages) and LM79xx (for negative voltages), and tensions are common fixed 5 V (for transistor logic circuits -transistor) and 12 V (for communications circuits and devices such as disk drives). In the fixed voltage regulators reference pin is connected to the land, while regulators in the variable reference pin is connected to the central point of a fixed voltage divider or variable supplied by the regulator output. A variable voltage divider (eg potentiometer) allows the user to adjust the regulated voltage. FixeUn regulatory 78xx series ICs assortment of “Fixed” three-terminal linear regulators are generally available to generate fixed voltages of more than 3 V, and ± 5 V, 9 V, 12 V or 15 V when the load is less than 1. 5 ampères.Le “78xx” series (7805, 7812, etc.) to regulate positive voltages while the “79xx” series (7905, 7912, etc.) to regulate negative voltages. Often, the last two digits of the device are the output voltage, for example, 7805 is a +5 V regulator, while 7915 is a regulator of -15 V. The 78xx series ICs can deliver up to 1. 5 amps depending on model. InventionLe regulators adjustable adjustable linear regulator first began April 12, 1977 in an article entitled Electronic Design “are detached from the fixed ICR regulations. The article was written by Robert Dobkin, a designer of integrated circuits, then worked for National Semiconductor. For this reason, National Semiconductor claims the title of “inventor LDO. Dobkin then left National in 1981 to found Linear Technology, where he is currently director of technology. OpérationPour output voltages not provided by the standard rules fixed and load currents of less than 7 amperes, commonly available “variable” to three-terminal linear regulators can be used. An adjustable regulator generates a fixed nominal low voltage between its output to “adjust” terminal (equivalent to the ground terminal in a fixed regulator). The “317″ series (1. 25V) regulates positive voltages while the “337″ series (-1. 25V) voltages négatives.réglables regulates voltage regulator circuit showing “adjust” terminalL’ajustement is done by constructing a voltage divider with its ends between the regulator output and the earth, and its center-tap connected to “adjust” terminal of the regulator. The ratio of resistors determines the output voltage using feedback mechanisms previously décrites.les complex energy needs (eg, op-amp circuits require matched positive and negative DC supplies) are more difficult, but only two IC Tracking adjustable regulators are available. Some even have choices and current limiting. An example is the series 419x.Notez some regulators, such as the LM317, require a minimum load. DispositifsPlus More complex controllers are available in packages of more than three pins, two packages online. Tensionréférence See aussiRégulateur of bandgap voltage BandgapLM317référence Brokawalimentation switching RéférencesLDO ^, Cruise, Low Dropout Regulators, Linear Regulators, Linear CMOSMises updated Inventor ^ At 30 Years Later, Classic External Links “Zener Regulator” to HyperPhysicsECE 327: LM317 Voltage Bandgap Reference Brief explanation Listing bandgap reference circuit independent of temperature in the LM317.ECE 327: Procedures for voltage regulators Lab provides diagrams, explanations and analysis for the shunt regulator Zener regulator series, series regulator feedback series regulator with limited feedback current regulator and series feedback with current notebook. also discusses the proper use of the LM317 voltage reference integrated circuit and bandgap capacitors dérivation.ECE 327: Report on Strategies for voltage regulators provides Lab more detailed quantitative analysis of the behavior of several shunt regulators set in and out of the reach of normal operation. “Regulator SPX1580 7A” Categories: Electrical power controlHidden: Articles to be merged since August 2008 | All Articles | Articles lacking sources from merged in January 2008 | All articles lacking sources