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LM2576-5.0V Power Supply Problem.

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ashish.talaviya

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I have LM2576-5.0V fixed 5V output IC both SMD and Through hole. When I use through hole IC, circuit works fine. When i give 12V 2A adpter input, it gives me 5V 2A output and i can charge my 10400mAH powerbank. But when i use SMD IC, it can't give me output. All Components in circuit are same, only i change IC. What is my mistake? I prepared hardware as per datasheet. Here is IC images, which i use and schematic. Capture1.JPGCapture2.JPG Capture.JPG
 

because its not heatsunk? or missing the 0v connection (tab on the TO-220)
 

maybe the part is damaged due to ESD , since it is mos based IC it should be handled properly
check your supplier and how are the components treated
 

chuckey said:
The IC is dissipating 7V X 2A = 14W, it needs a heatsink. The IC might be OK it just closed it self down on thermal over temperature.
Frank
Click to expand...

what ??!!
this is a switching regulator , how did u calculate the power dissipation
 

IC gives me +5V, But it, can't give current. When I connect Powerbank to charge, it can not pass current. The voltage fluctuates.
 

ashish.talaviya said:
IC gives me +5V, But it, can't give current. When I connect Powerbank to charge, it can not pass current. The voltage fluctuates.
Click to expand...

my advise buy new ICs from mouser or digikey or any good manufacturer and test again
 

Hi there,

if you consult datasheet and observed pinning configuration well then, yet replacement of packages even at same device wont guaranty that it would work, you still need to check/ tweak passive components values or tolerance. check also the induct or value.

Best regards,
 

Have you checked with alternate SMD part? If not try it out & let us know if still problem persists.
 

I also tried with new piece, but all IC look like old. So it is seeming that they will not work. So i order new IC.
 

Hi,

show us a picture (or more) of the circuit with SMD device, where we can see all connectons.

Klaus
 

KlausST said:
show us a picture (or more) of the circuit with SMD device, where we can see all connectons.
Click to expand...

There is no difference at the connections of both SMD & through hole part. Then why circuit is required? Just want to know the reason for asking circuit.
 

Hi,

There is no difference at the connections of both SMD & through hole part. Then why circuit is required? Just want to know the reason for asking circuit.
Click to expand...

I've done many repair and debugging. Always the text says "The circuit is according datasheet" or "there is nothing changed"...
But sometimes a second pair of eyes sees what the first doesn't see.

Klaus
 

KlausST said:
I've done many repair and debugging. Always the text says "The circuit is according datasheet" or "there is nothing changed"...
But sometimes a second pair of eyes sees what the first doesn't see.
Click to expand...

Agreed!!!

Actually my doubt lies at the circuit assembly or connection & not at the circuit diagram. If there is just simply drop in replacement between these two IC's without disturbing the remaining parts then surely problem lies on the SMD IC.
 

Hi,

I didn´t mean the circuit diagram, but a photo...


Klaus
 

Hi,

Please check if the heatsink of the package is connected to ic vcc or gnd base of the wafer, it is very important !

Bill Lee
 

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