Patent ID: 11942871
Assignee: CYPRESS SEMICONDUCTOR CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 0:
1. A method, comprising:
receiving, at a primary side controller in an alternating current to direct current (AC-DC) converter, a rectified AC voltage through a pair of diodes, wherein the primary side controller is coupled to a discharge circuit and the discharge circuit is configured to discharge an external capacitor based on an undervoltage threshold;
determining, by the primary side controller, whether a control signal has been received from a secondary side controller, wherein the primary side controller is on a primary side of a transformer and the secondary side controller is on a secondary side of the transformer;
in response to determining that the control signal has not been received, increasing, by the primary side controller, a duty cycle of a primary field effect transistor (FET) that is coupled to the transformer;
determining, by the primary side controller, whether the rectified AC voltage of the AC-DC converter is below the undervoltage threshold;
in response to determining that the rectified AC voltage of the AC-DC converter is below the undervoltage threshold:
determining, by the primary side controller, a current duty cycle of the primary FET; and
turning off, by the primary side controller, the primary FET.