Switching power supply TL431 what role, I did not find the circuit in 431 the corresponding circuit
Capacitor in the role of the circuit: with blocking DC, connected to the exchange, to prevent low-frequency characteristics,
widely used in the soft-start capacitor: generally connected to the switching power supply on the base of the switch to prevent the power,
TL431 is used as a voltage sampling drive optocoupler, if the output voltage Vout changes, TL431 the reference side by the R1 and Rlower partial pressure control, making the TL431 regulator value changes, so optocoupler light-emitting diode (negative) Voltage changes, the current in the LED changes, making the optocoupler output photoelectric transistor conduction changes, Vfb output voltage also changes, to achieve the feedback output voltage changes and isolation, the output voltage Vfb sent to the switch control circuit, in order to achieve closed-loop Regulation. Here Vout increases - VFB drops.
