View str-g6651 datasheet:

STR-G6651 OFF-LINE QUASI-RESONANT FLYBACK SWITCHING REGULATOR The STR-G6651 is specifically designed to satisfy the requirements for increased integration and reliability in off-line quasi-resonant flyback converters. This device incorporates the primary control and drive circuit with a discrete avalanche-rated power MOSFET. FDBK Cycle-by-cycle current limiting, under-voltage lockout with hyster- esis, over-voltage protection, and thermal shutdown protects the power OSC. LATCH supply during the normal overload and fault conditions. Over-voltage protection and thermal shutdown are latched after a short delay. The latch may be reset by cycling the input supply. Low-current startup and UVLO a low-power standby mode selected from the secondary circuit completes OVP TSD