Texas Instruments Corporation

Jose Vidal, Jr

Vijay Choudhary

Dinesh Katam

A converter control circuit includes a terminal to be coupled to a switch node. The control circuit includes a valley sensing circuit coupled to the terminal and detects valleys in an oscillating voltage on the switch node. The valley sensing circuit has a first output and asserts a first control signal on the first output indicative of occurrence of a valley. A logic gate has a second output and asserts a second control signal on the second output to turn on a switching transistor. A switch-on control circuit has a first input and a second input. The first input couples to the first output. The second input couples to the second output. The switch-on control circuit asserts a third control signal to turn on the switching transistor responsive to the second control signal indicating that the switching transistor is to be on while the first control indicates a valley.

Controller for a flyback converter

In operation of a flybuck converter, a first output capacitor is charged and, after this charging, charge is transferred from the first output capacitor to a second output capacitor. The charge transferring includes closing a switch to establish a first current path through which the first output capacitor discharges current that induces, in a second current path, current that charges the second output capacitor. While the switch is closed during the charge transfer, a current limit condition in the switch is detected. In response to detection of the current limit condition, the switch is opened, and is thereafter closed again before attempting to charge the first output capacitor again, thereby to resume transferring charge from the first output capacitor to the second output capacitor.

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Phoenix, AZ, United States of America

Jose Vidal, Jr