Dear Friends,

I am using Atmega328P, input source of 12V10A with 7805 Voltage Regulator, when I connect the input source the regulator Capacitor got burnt.

Kindly advice, if we need to add 7812 voltage regulator before 7805?

Below Schematic

 

No reason to, 47uF should be fine as long as its a good brand and not a cheap fake, or a very old dried out one, or wired in back-to-front. Suggest a 16 or 25v rated version, 1000v seems a little excessive.

When you say 'burnt' what exactly happened to it?

 

Where did you get a 47uF 1000V capacitor? The two listed on Mouser.com are $60 each. Somehow I doubt that that is what you have. So I also doubt that it is 47uF. What is it really?

Bob

 

Thank you very much Mr. Irving for immediate support.

It was blunder mistake done while connecting the input source. I have corrected now and it is working fine. As you have suggested capacitor 1000v is not required, I have changed to 47uF 25v.

Bhimsen

 

The capacitor should not have been damaged if it was wired correctly. Did you connect the capacitor the wrong way round?

 

Input Source was wired wrongly, after correcting got the output of 5v as required for the MC.

Thanks All for the guidance.

 

Dear Friends,

I am using Atmega328P, input source of 12V10A with 7805 Voltage Regulator, when I connect the input source the regulator Capacitor got burnt.

Kindly advice, if we need to add 7812 voltage regulator before 7805?

Below Schematic

View attachment 240453

You misconnected something- which is why you should also have a fuse and/or diode on the input power. Secondly, your LM7805 will run a bit hot because you are forcing it to drop ~7V... it has to dissipate that energy. You could use a zener/transistor circuit ahead of the LM7805 to drop the voltage, or use an LM7808 to approximately halve the 7V problem, which will let the LM7805 run cooler.

Remember Thermal Junction Temperatures- you run high voltage, you lose the ability to pass current. The lower your voltage, the more current you can pass through a given junction.

Using your numbers- 12V in, and 5V out, without a heatsink, the max current you can get out of an LM7805 while keeping it at 38.8C is 318mA:



If you make the input 8V into the LM7805 it becomes:



And if you add a TO-220-3 heatsink (assuming you're using a TO-220 package LM7805):

 

@BobaMosfet ~ Awesome spreadsheet

 

@click_here Thank you. I find using tools I create saves a lot of time, and promises a higher general level of accuracy than doing it from scratch everytime.