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Problem with power supply of microcontroller

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stoyanoff

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Hi! I`m using 18F4431 to run a frequency inverter. So here is the chart View attachment microchip.pdf
So when the chart runs without the load everything is OK. But when I connect the engine after 2-3 seconds the controller resets. I measured the power supply and it drops to 2V. Can you tell me what else I can do to fix this???
Thanks!
 

Connect a diode between rectifier pin 2 and U2 pin 1.

How long does the voltage stay that low?
 

So when the chart runs without the load everything is OK. But when I connect the engine after 2-3 seconds the controller resets. I measured the power supply and it drops to 2V.
Click to expand...

How much current is drawn from 7805? If it is above specifications, then output voltage drop would be a realistic scenario.
 

hi,
Most probably a curent surge produces the voltage drop on ac main supply and your transformer has <1 VA power rating, try a different transformer 220/12 V ; 5VA ... or whatever standard type transformer that is greater than the one that you use now
 

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