PMP9310, 3.3V Low-Cost Non-Isolated Offline Converter for Smart E-Meters Reference Design. The PMP9310 is an offline converter that supplies 3.3VDC output at up to 132mA. It is used for 50Hz single-phase smart e-meters where maximum allowable input apparent power is regulated (typically 4VA) and galvanic isolation is unnecessary. It solves the problem of limited available output power typically seen in a linearly regulated output stage. By employing the wide input LM5017 buck switcher, the capacitor-drop design sets the input of the DC-DC stage at a high value of 72V and extracts significantly more power from the mains at a given input apparent power