The MP158 is a primary-side regulator that provides accurate constant voltage (CV) regulation without opto-coupler. It supports Buck, BuckBoost, Boost and Flyback topologies. It has an integrated 500V MOSFET to simplify the structure and reduce costs. These features make it an ideal regulator for off-line low power applications, such as home appliances and standby power. MP158 is a green-mode-operation regulator. Both the peak current and switching frequency decrease as the load decreases. This feature provides excellent efficiency at light load, thus improving the overall average efficiency. MP158 features various protections, including thermal shutdown (TSD), VCC under-voltage lockout (UVLO), overload protection (OLP), short-circuit protection (SCP), and open loop protection. MP158 is available in small TSOT23-5 package and SOIC8 package.Primary-side constant voltage (CV) control, supporting Buck, Buck-Boost, Boost and Flyback topologies Integrated 500V MOSFET and current source <30mW no-load power consumption Up to 2W output power Maximum DCM output current less than 40mA Maximum CCM output current less than 70mA Low VCC Operating Current Frequency foldback Limited maximum frequency Peak-current compression Internally biased VCC Thermal shutdown (auto restart) VCC under voltage lockout with hysteresis Timer based over-load protection Short-circuit protection Open-loop protection