In: Electrical Engineering
When i went to the lab, and measure the output voltage of the 7805 VOLTAGE REGULATORS by connecting it to either 12 voltage or 9 voltage, The output was the same which is 4.94.
I need the equation to calculate and calculate it with full steps mathematically
LM78xx series of ic are known as voltage regulators which provide constant output voltage at any input voltage ( within permissable range of ic) . So in your case you are using LM7805 which means it provide output voltage=5v idealy.
But in practice there is significant voltage drop in ic which makes output voltage little bit lower than 5v and in your case you are getting 4.8 which is in permissable limit . Since ic consist many of transistor,capacitor ,resisters whithin itself there is no single equation to calculate for that output voltage. Now, every ic have some input output voltage range and for 7805
Input voltage range = (7-30) v
Output voltage range =(4.8 -5.2) v
So you will get output in range of 4.8-5.2 when you apply voltage in range of (7v-30v) . In regulator ic7805 when the input voltage exceeds from 5v that extra volatge will be converted in heat for which heat sink is required . And there is a mathamatical expression for the quantity of heat which is dissipated by ic = heat generated= (input voltage-5)x(output current) for example if we have 15 v input voltage and output required current is .5amp then power wasted in heat = (10-5)*.5 = 5w . I hope you understand what ever i was trying to say .