I'm looking for some help with understanding (in fact, correcting or confirming my understanding) of how the following circuit works:
U1 here is TL431 voltage regulator, for example from Texas Instruments. This circuit is intended to provide a regulated voltage over Vout pins, and I'm looking for proper explanation how that is achieved. Here is what I managed to figure out:
At some moment, U1 is closed and current is flowing from Vin through R1 resistor directly to the Q1 gate, which opens the transistor at some voltage. In that way, we achieve some voltage at Vout, but we want some regulated, i.e. constant voltage, more or less independent of a load resistance being connected to the output.
When the volate at the source pin of Q1 reaches some point, determined by resistor divider on R2, R3 and R4, U1 opens and current starts to flow through R1, then U1, reducing the voltage applied to Q1 and thus partially closing it, which reduce the voltage at Q1 source pin.
If we remove C2 and C3 capacitors from the circuit, we should see some the pulsations at Vout pin, caused by this transistor opening/closing.
Please let me know if my understanding is correct and if not, how this circuit achieves regulation.
Also if this question is not quite suitable for this site, I do apologise and will remove it.