help needed on attached circuit

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Hi all,

Attached is a AC - DC circuit with a power factor corrector IC. From the attachment when a pulse is given to the gate of the MOSFET, so current would flow from drain to source. My question is wouldn't it short the circuit and lead to fatal circuit blow.
 

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Not unless the controller causes the inductor to saturate. When the Mosfet is switched on, the inductor resists the flow of current, limiting that amount of power drawn. The inductor will restrict current flow until it reaches saturation. So as long as the mosfet is switched off before the inductor saturates, it will operate without a problem.
 
Hi Jegandren,

No, the circuit will not be shorted. The schematic you have given is the schematic of a Non-isolated flyback circuit. The non-isolated flyback turns on the MOSFET for a fraction D of the switching period, which, since it produces a voltage across the inductor, causes current to ramp up, storing energy in the inductance. When the MOSFET turns off, the inductor current goes through the diode and into the output capacitor and load. The non-isolated flyback should have a single output (there is no way to make more than one). The output is not isolated from the input and the output cannot be made less than the input voltage - even if you turn the MOSFET completely off, the output will equal the input (minus a diode drop).

Frequently people call the non-isolated flyback a 'boost' converter, which is not appropriate.

Thanks.
 
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