When an overvoltage condition occurs, such that bias voltageexceeds the sum of VR2 and the BYPASS/MULTIFUNCTION (BYPASS/MULTI-FUNCTIONAL) pin voltage, current begins to flow into theBYPASS/MULTI-FUNCTIONAL pin. When this current exceeds ISD theinternal latching shutdown circuit in TinySwitch-4 is activated. Thiscondition is reset when the ENABLE/UNDERVOLTAGE pin currentflowing through R12 and R13 drop below 18.75 mA each AC linehalf-cycle. The configuration of Figure 16 is therefore non-latching foran overvoltage fault. Latching overvoltage protection can beachieved by connecting R12 and R13 to the positive terminal of C2,at the expense of higher standby consumption. In the exampleshown, on opening the loop, the OVP trips at an output of 17 V.