Switching Mode Power Supply Current Control via LEB Adjustment

The patent applies preliminary action by implementing a leading edge blanking (LEB) function that proactively manages the turn-on transient period of the switching device. The LEB circuit preemptively controls the leading edge of the drive signal to ensure proper timing, preventing excessive current before it can occur. This preliminary control mechanism addresses the turn-off time delay issue by establishing proper timing margins in advance.

The patent implements feedback through a sensing resistor connected in series with the switching device that monitors the actual current flow. This sensing feedback is fed to the PWM unit, which uses the information to adjust the drive signal timing and prevent excessive current. The feedback mechanism continuously monitors and corrects timing deviations caused by circuit delays, ensuring reliable operation at high output voltages.

During soft start operation, the patent applies preliminary action by using the LEB function to pre-establish proper timing relationships before the switching device begins its transition. The LEB circuit prepares the drive signal timing in advance, ensuring that even as the output voltage gradually increases during soft start, the switching device maintains proper turn-off timing and avoids excessive current.

The patent applies parameter changes by dynamically adjusting the LEB time period based on operating conditions. During soft start, the LEB time is optimized to accommodate the gradual voltage increase while preventing excessive current. The sensing resistor monitors current parameters in real-time, and the PWM unit adjusts timing parameters accordingly to maintain stable operation throughout the soft start sequence.