fendertunes
Junior Member level 1
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I have searched for this a lot (on this forum and google). Can someone verify/explain how this circuit works?
Here is my understanding: TL431 has a ~2.5V reference. The resistor divider of R1/Rlower creates a divided down output voltage. The difference between the output and 2.5V reference is the "error signal". C1 acts as an integrator to TL431, so any error gets bigger quick (as C1 charges) and regulates the TL431 output. RLed limits the current through the opto, and the CTR ratio of the opt provides the current on the collector of Opto. The drop across Rbias provides a bias current to the opto, not sure why? When the opto turns on (with enough current flow in the diode), the output of the opto is: Vfb = (Vd0 - V_Rpullup). C2 is for high frequency switching noise.
Is this how this circuit works? In general, whats the purpose of this circuit? When the opto turns on, does it mean the "smps controller" stops switching till the opto-turns off?
I have searched for this a lot (on this forum and google). Can someone verify/explain how this circuit works?
Here is my understanding: TL431 has a ~2.5V reference. The resistor divider of R1/Rlower creates a divided down output voltage. The difference between the output and 2.5V reference is the "error signal". C1 acts as an integrator to TL431, so any error gets bigger quick (as C1 charges) and regulates the TL431 output. RLed limits the current through the opto, and the CTR ratio of the opt provides the current on the collector of Opto. The drop across Rbias provides a bias current to the opto, not sure why? When the opto turns on (with enough current flow in the diode), the output of the opto is: Vfb = (Vd0 - V_Rpullup). C2 is for high frequency switching noise.
Is this how this circuit works? In general, whats the purpose of this circuit? When the opto turns on, does it mean the "smps controller" stops switching till the opto-turns off?