Tuesday, May 5, 2020

LM In LM7805 Linear Monolithic- Free Sample

Question: Describe about the LM in LM7805 for Linear Monolithic. Answer: LM in LM7805 stands for Linear Monolithic. It depicts manufacturer's code. LM7805 is a integrated circuit which performs the function of voltage regulation. When the voltage source fluctuates in a circuit the output voltage also varies. Output voltage is maintained at a constant value by the voltage regulator Integrated Circuit LM7805. It provides a positive five volts regulation. (Kushagra,2012). The diagram illustrates the internal blocks present in the LM7805 IC The LM7805 is a three-pin Integrated Circuit. Pin 1 is accepts the input DC voltage.This voltage is regulated to 5 volts. Pin 2 establishes the ground for the regulator. Pin 3 provides output of 5 volts DC(LearningaboutElectronics,2012). Reference voltage is the voltage needed for purpose of reference in LM7805. An electronic circuit produces the reference voltage without being affected by changes in temperature or variations in supply voltage. Over passage of time,the same reference voltage is produced by the circuit and hence the voltage is stable in nature. The voltage reference circuit used commonly is the bandgap voltage reference(Future Electronics,nd). A voltage reference is a electronic system that produces a fixed (constant) voltage irrespective of the loading on the device,sudden or gradual change in temperature, power supply changes, temperature changes, and the passage of time. Reference voltages find application in measurement systems,power supplies, analog-to-digital converters, digital-to-analog converters, control systems. Voltage references exhibit wide variation in performance. For instance a power supply regulator in a computer may retain its value, within a few percentage of the nominal value. Parts per million or ppm is the measurement standard for laboratory voltage standards which have high degree of precisions and stability. A starting circuit for a voltage regulator consists of a suitable means for providing an input current. It has mechanism for receiving voltage from the regulator(Gontowski,1987) The series pass element or the series pass regulator provides final voltage regulation in the LM7805 IC. A variable element is used in series with the load in the circuit for the purpose.(Poole,nd). The safe operating area related to a transistor consists of description of all maximum values of collector current or drain current and collector to emitter voltage or drain to source voltage combinations which does not result in destruction of Bipolar junction transistor or Field Effect Transistor. The regulator IC is protected by the SOA protection circuit against excessive or dangerous values of voltages and currents which may accidentally flow in the circuit due to uncontrolled factors. The circuit limits the output load current when the device is operated in the danger zone(Didden,2008). The Thermal protection circuit detects overheating of the voltage regulator when the output pin is shorted to ground pin. The operation of voltage regulator is stopped and is protected from damage(Ricoh,nd). The error amplifier is a building block of linear or switching regulated power supply. An error amplifier acts as a comparator. A sample of the output voltage is fed back and compared to the reference voltage. The difference between the two voltages produces a compensating error voltage. Error amplifier compares the difference between the two signals. Its main characteristic is gain since larger the gain, smaller the error that can be compared(Edaboard,2005). A current generator in the regulator IC is an electronic circuit which delivers an electric current independent of the voltage across it. References: Kushagra.(2012). In IC 7805 (Voltage Regulator IC). Retrieved from https://www.engineersgarage.com/electronic-components/7805-voltage-regulator-ic LearningaboutElectronics(2012). In What is a LM7805 Voltage Regulator? Retrieved from https: //www. learningaboutelectronics.com/Articles/What-is-a-LM7805-voltage-regulator Future Electronics(nd). In What is a Voltage Reference?. Retrieved from https://www.futureelectronics.com/en/regulators-references/voltage-references.aspx Gontowski, W. S., Jr. (1987). Voltage regulator start-up circuit. Retrieved from https://www.google.co.in/patents/US4740742 Poole,Ian (nd).In Series Voltage Regulator (Series Pass Regulator). Retrieved from https://www.radio-electronics.com/info/power-management/linear-power-supply- psu/series-voltage-regulator-theory-circuit.php Didden,Jan(2008). In Safe Operating Area calculations. Retrieved from https://linearaudio.nl/safe-operating-area-calculations Ricoh(nd) In Voltage Regulator Application Note. Retrieved from https://www.e-devices.ricoh.co.jp/en/products/product_power/ap_note/vr02.html Edaboard (2005). In what is error amplifier and how to design it?. Retrieved from https://www.edaboard.com/thread52721.html

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