{525} Role of Auxiliary Winding / VCC or Bias Winding In SMPS Switch Mode Power Supply

in this video i explained the Role of Auxiliary Winding / VCC or Bias Winding In SMPS Switch Mode Power Supply. what is aux winding and how auxiliary winding works
in most of the topologies, the pwm IC require a low power supply of about 10- to 45-V output. It is used to feed the usual pulse-width-modulating (PWM) chip for the main “power train / dc rail,” and power the logic and sensing circuits that perform various housekeeping
functions. Such housekeeping functions may include over-current sensing, over-voltage sensing and protection, remote signaling, and correction of turn “on” and turn “off” sequencing for each output in a multi-output supply.
in initial startup, when there is no power output, in that stage a startup current is provided through a startup resistor, which charges the vcc capacitor connected to the vcc pin of smps pwm controller ic, at a specific voltage threshold that ic will start switching and smps transformer will start to induce voltage in secondary. thus there is a secondary winding (named aux winding / vcc winding / bias winding) which's one end is connected to primary ground and its second end is connected to a rectifier, which will rectify that voltage will fed to the vcc pin