description: This article will focus on using a TL431 shunt regulator to turn off the feedback loop of the isolated power supply. The article will discuss a way to extend the power control loop bandwidth to improve transient loads and line response. Figure 1 shows a typical schematic of an offline isolated reverse converter. The output voltage is shunted down and compared to the TL431's 2.5 V reference. If the output voltage is too high, the TL431 will shunt the current through its negative. A portion of this shunt current flows through the optocoupler diode (U2) and is reflected in the phototransistor. The mirror current increases the voltage of R16, which reduces the peak current of the power MOSFET, which reduces the output voltage of the power supply. Interestingly, there are two optocoupler-related feedback paths; one through the TL431 and the other associated with the output voltage R8. The TL431 path is obvious because the sample of the output voltage is compared to the reference voltage, amplified, and then used to drive the optocoupler. The R8 connection is easy to see, and the current through R8 is the difference between the output voltage and the TL431 negative voltage. The current through R8 varies proportionally with the output voltage and is independent of the TL431 negative voltage. If the output voltage is to rise, the current in the resistor and optocoupler diode will increase, reducing the output voltage. Cast Iron LV 3PH Asynchronous Motor Cast Iron Lv 3Ph Asynchronous Motor,Three Phase Asynchronous Cast Iron Motors,Cast Iron Motors,Cast Iron Electric Motor Yizheng Beide Material Co., Ltd. , https://www.beidevendor.com