Tell me the operation of regulator ic 7805 in detail?


1 of old , still popular voltage regulators. 78xx family linear positive regulator xx denotes output voltage (so 7805 5v out), while 79xx negative.
include basic protection may not protect ic overload, overtemperature etc. since old, quiescent current quite large (~10ma) while modern regulators 100x less. job, 78xx need considerable voltage drop 2.5v. means 5v out, input must @ least 5v+2.5v=7.5v or don't regulation. there issue of power dissipation. being series regulator, full load current passes through 78xx well. if input voltage large , output voltage low , current insignificant, these regulators need massive heatsinks. lately there many pin-compatible replacements use switching mode (smps) , not need heatsinks. quite convenient when example deriving 5v 24v. smps versions still considerably more expensive prices dropping

7805 small heatsink:
http://www.trainelectronics.com/artcles/...

compatible smps version 5v regulator needs no heatsink (here oki-78sr):
http://media.digikey.com/photos/murata%2...



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