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US 10,855,188 B2Granted
Hybrid secondary-side regulation
AssigneeDialog Semiconductor GmbH
InventorsYong Li, Cong Zheng, Xiaoyan Wang, Wenduo Liu
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Abstract
A flyback converter control architecture is provided in which primary-only feedback techniques are used to ensure smooth startup and detection of fault conditions. During steady-state operation, secondary-side regulation is employed. In addition, current limits are monitored during steady-state operation using primary-only feedback techniques to obviate the need for a secondary-side current sense resistor.
Claims6
A method for a flyback converter, comprising:
- during a constant-voltage mode of operation in a secondary-side controller for the flyback converter, comparing an output voltage for the flyback converter to a reference voltage to determine a control voltage;
- transmitting the control voltage from the secondary-side controller to a primary-side controller;
- in a pulse width modulation mode of operation for the flyback converter, processing the control voltage to determine a desired peak current for a power switch;
- following a cycling on of the power switch in a first power switch cycle, switching off the power switch responsive to a current through the power switch equaling the desired peak current;
- following the switching off of the power switch, determining a transformer reset time from an auxiliary winding voltage;
- determining an average output current for the flyback converter from the transformer reset time and the peak current through the power switch;
- and
- when the average output current is greater than an output current limit, transitioning the flyback converter to a constant-current mode of operation in a second power switch cycle following the first power switch cycle in which the primary-side controller does not use the control voltage.
5 more elements
Dependencies are inferred from the claim text.