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MC34063 Simulation-0v at pin 5

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adeel.sid

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Hello

In a project, I have to test working of MC34063, my calculation shows that I will get 5.75V at output (pin 2 right?) that indirectly connected to pin 5.
I checked that voltage varies b/w 9-10 (at N38) and current also fluctuates.

I have attached image of proteus simulation file as reference

Can anyone guide?

Regards
 

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There are dots along the circuit that means you certainly had not connected correctly some components, and this could explain the fluctuating voltage due to some unconnected net. Once it is a simple schematic, I suggest you redraw all of them.
 

andre_teprom said:
There are dots along the circuit that means you certainly had not connected correctly some components, and this could explain the fluctuating voltage due to some unconnected net. Once it is a simple schematic, I suggest you redraw all of them.
Click to expand...

I tried to reconnect, but dots appears whenever there are more than one path. For confirmation, I checked voltage after dots to be sure about continuity. All works same

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sabouras said:
The pin 2 goes to 5 with inductor not with capacitor.
Click to expand...

exploring output since both are energy storage device.

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Problem is 0v (up to 3 decimal point) on pin 5
 

adeel.sid said:
.........................
exploring output since both are energy storage device.
......................
Click to expand...
The are both energy storage devices but that certainly doesn't mean you can substitute one for the other. :???: One stores energy with voltage/charge, the other stores energy in the current flow.
 

Right!
I tried to replace it with inductor of value calculated through given link. But no good result:(
 

"no good results" means that is not working as expected, or even not working ?
 

andre_teprom said:
"no good results" means that is not working as expected, or even not working ?
Click to expand...

when i place probe, i got some values (almost zero and changing continuously)

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SunnySkyguy said:
This cannot possibly work with only a tiny cap on the emitter (SWE) and no inductor.
Click to expand...

As posted above, i tried it by replacing cap with inductor but cant get expected result (5.75V at 2)
By the way, I'm right when I say out at pin 2 or it should be at other pin?
I'm using this IC first time and confused
 

By the way, I'm right when I say out at pin 2 or it should be at other pin?
I'm using this IC first time and confused.
Click to expand...
If you review the datasheet, you see different ways to connect the IC. For a buck converter with internal switch the output is SWE (switch transistor emitter). By nature of the buck converter, there must be a DC path between input and output. So please forget about the silly series capacitor circuit in your original post.

The other question is, why the standard inductor circuit isn't working for you. But this can be hardly guessed without detail informations.
 

Hi,

please show your actual schematic and descirbe the results.

Klaus
 

Also might specify the main requirements such as: switching frequency, desired output voltage, and maximum load current.
 

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