Abstract: A power factor correction controller is disclosed which extracts RMS information from a rectified AC input line voltage signal using a sample and hold analog to digital conversion approach. The controller then processes a digital word representing the RMS information through the application of a programmable mathematical function. The result is converted to analog form and provided as an input to an analog multiplier. The controller also monitors the output load power of an isolated boost converter circuit and linearly reduces the overlap delay time of a MOSFET transition switch when the load power decreases.

Abstract: An integrated circuit controller for a switching power converter implementing feed-forward and synchronization features. The controller IC has pins which permit dual functionality. The feed-forward feature is implemented with a supply voltage from an unregulated auxiliary winding which additionally powers the controller. The synchronization feature is implemented by coupling an external synchronization signal to a feedback pin of the controller IC to which a feedback signal from the output of the converter is also coupled.

Abstract: A synchronous step-down DC to DC converter includes a bootstrap capacitor monitored by a controller for maintaining a desired bootstrap voltage to drive a high side NMOS switch. The controller temporarily increases the duty cycle of the low side NMOS switch when the bootstrap voltage decreases below a predetermined level to maintain a minimum level of charge on the bootstrap capacitor.