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[Moved]: 5v POWER SUPPLY PROBLEM

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dp1311.dp

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Hello,
as per attachment
when i connect lm7805 instead of lm78l05 the mosfet q1 is short
what will be the problem and how to solve that
 

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  • Battery charger 25917.pdf
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Re: 5v POWER SUPPLY PROBLEM

Hi,

Maybe:
* LM7805 is defective
* it is no 7805
* you connect it the wrong direction

can you show two picures:
* PCB with 78L05 connected
* PCB with LM7805 connected.

Klaus
 

Re: 5v POWER SUPPLY PROBLEM

I am connection proper input output pins of lm7805 as per datasheet
if there is no micro-controller connected circuit works fine
after connecting that it create the problem as i said
 

Re: 5v POWER SUPPLY PROBLEM

I also want to know that mosfet Q1 works correctly as a diode??
 

Re: 5v POWER SUPPLY PROBLEM

dp1311.dp said:
I also want to know that mosfet Q1 works correctly as a diode??
Click to expand...
Q1 is NOT in a diode connected configuration... if that was what you were thinking.
The way Q1 is connected looks like a reverse polarity protection. I guess you took care of its maximum source-gate voltage.
 

Re: 5v POWER SUPPLY PROBLEM

Yes i am using it as a reverse polarity protection. Is it proper connection??
Does this configuration cause problem to the lm7805??
Because the circuit works correctly with the lm78l05 but when i connect lm7805 Q1 goes short
 

Re: 5v POWER SUPPLY PROBLEM

dp1311.dp said:
Is it proper connection??
Click to expand...
Yes.
Does this configuration cause problem to the lm7805??
Click to expand...
No.
Because the circuit works correctly with the lm78l05 but when i connect lm7805 Q1 goes short
Click to expand...
Q1 is supposed to be a short circuit whenever the proper polarity source is applied.
 

Re: 5v POWER SUPPLY PROBLEM

Mosfet gets totally short circuited means gate drain and source all are short with each other
What can i do for this problem
 

Hi,

Is Q1 backwards ? USB VCC 78 something or other hard to read is an output is it, not an "IN"? I think that Q1 is connected incorrectly.
 

dp1311.dp said:
What can i do for this problem
Click to expand...
Start with a better schematic and re-read post #2.

d123 said:
Is Q1 backwards ? [..] I think that Q1 is connected incorrectly.
Click to expand...
The solar panel charges the battery when the "PANEL_PWM_OC0B" says so. Otherwise, the battery does not get any charge because the Q2 P-MOSFET's Source-gate is shorted by the solar panel.

That being said, Q1 is a reverse polarity protection circuit for the solar panel inputs and Q2 controls when the battery is being charged via controlling Q3, respectively "PANEL_PWM_OC0B".
 
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    d123

    d123

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Everything was worked properly with lm78L05 which has a 5v/100ma output,somtimes after 3/4 hours of continues working it get hot.
So to solve that i was suggested to use lm7805 which gives 5V/1amp output,when i connect pin1 of the lm7805 to the input means after D2 and D3 in my circuit and pin 3 to the output means +5V connections of the circuit,pin 2 to the circuit ground,after doing this it makes burn the microcontroller and mosfetQ1,and lm7805 still gives 5v output it doesnt effected by all this.
Which part cause the problem
 

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