A high-voltage electrolytic smoothing capacitor (typically rated at 4.7µF / 400V ) flattens the voltage ripples. When running off standard 220V AC mains, this stage produces a steady internal backbone voltage of roughly 310V DC across the main power traces. 3. The PSR Switching Controller IC
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The heart of the module is an offline Primary-Side Sensor Controller chip, often designated as the (or a comparable alternative like the TOP254YN in some board variations). wx-dc12003 schematic